Trends in Civil Engineering and Challenges for Sustainability: Select Proceedings of CTCS 2019 [1st ed.] 9789811568275, 9789811568282

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Lecture Notes in Civil Engineering

M. C. Narasimhan Varghese George G. Udayakumar Anil Kumar   Editors

Trends in Civil Engineering and Challenges for Sustainability Select Proceedings of CTCS 2019

Lecture Notes in Civil Engineering Volume 99

Series Editors Marco di Prisco, Politecnico di Milano, Milano, Italy Sheng-Hong Chen, School of Water Resources and Hydropower Engineering, Wuhan University, Wuhan, China Ioannis Vayas, Institute of Steel Structures, National Technical University of Athens, Athens, Greece Sanjay Kumar Shukla, School of Engineering, Edith Cowan University, Joondalup, WA, Australia Anuj Sharma, Iowa State University, Ames, IA, USA Nagesh Kumar, Department of Civil Engineering, Indian Institute of Science Bangalore, Bengaluru, Karnataka, India Chien Ming Wang, School of Civil Engineering, The University of Queensland, Brisbane, QLD, Australia

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M. C. Narasimhan Varghese George G. Udayakumar Anil Kumar •

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Editors

Trends in Civil Engineering and Challenges for Sustainability Select Proceedings of CTCS 2019

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Editors M. C. Narasimhan Department of Civil Engineering National Institute of Technology Surathkal, Karnataka, India

Varghese George Department of Civil Engineering National Institute of Technology Surathkal, Karnataka, India

G. Udayakumar Department of Civil Engineering N.M.A.M. Institute of Technology Nitte, Karnataka, India

Anil Kumar Department of Civil Engineering N.M.A.M. Institute of Technology Nitte, Karnataka, India

ISSN 2366-2557 ISSN 2366-2565 (electronic) Lecture Notes in Civil Engineering ISBN 978-981-15-6827-5 ISBN 978-981-15-6828-2 (eBook) https://doi.org/10.1007/978-981-15-6828-2 © Springer Nature Singapore Pte Ltd. 2021 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Singapore Pte Ltd. The registered company address is: 152 Beach Road, #21-01/04 Gateway East, Singapore 189721, Singapore

Organizing Committee

Committee Members Patron Shri. N. Vinaya Hegde, Chancellor, Nitte (Deemed to be University) President, Nitte Education Trust, Mangalore Steering Committee Sri. Vishal Hegde, Pro-chancellor, Nitte (Deemed to be University) Dr. N. R. Shetty, Chancellor, Central University, Karnataka Dr. B. S. Sonde, Director, ASM Technologies Ltd. Dr. G. Hemanth Kumar, Vice Chancellor, Mysore University Dr. Omid Ansary, Senior Associate Dean and Professor, Penn State University, USA Dr. Samson Ojawo, Professor, Ladoke Akintola University of Technology, Nigeria Dr. Shripad T. Revankar, Professor, Purdue University, USA Dr. Shuhaimi Mansor, Professor, Universiti Teknologi Malaysia General Chair Dr. Niranjan N. Chiplunkar, Principal, N.M.A.M. Institute of Technology, Nitte Co-chair Dr. I. R. Mithanthaya, Vice Principal and Dean (Academics) Dr. B. R. Srinivas Rao, Vice Principal and Controller of Examinations Conveners Dr. Sudesh Bekal, Dean (R&D) Dr. Muralidhara, P. G. Coordinator Organizing Secretary Dr. Gururaj Upadhyaya, Department of Mechanical Engineering v

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Organizing Committee

Web Coordinators Dr. Sarika Hegde, Department of MCA Mr. Rajeevan, System Administrator Organizing Committee Sri. Yogeesh Hegde, Registrar (NET Campus) Dr. Subrahmanya Bhat, Professor and Dean (Student Welfare, ISO and IQAC Coordinator Dr. K. Rajesh Shetty, Dean (Admission and Alumni Affairs) Dr. Srinath K. Shetty, Professor and Resident Engineer Dr. P. Srinivas Pai, Deputy Controller of Examinations Dr. Uday Kumar K. Shenoy, Professor, Department of Computer Science and Engineering Dr. P. Shankaran, Professor and Head, Department of Mathematics Dr. K. B. Manjunath, Assistant Professor and Head, Department of Physics Dr. Ramesh Bhat, Associate Professor and Head, Department of Chemistry Dr. H. Divakar Bhat, Librarian Dr. B. Rashmi Hegde, Professor and Head, Department of Humanities Mr. Krishnaraja Joisa, Public Relation Officer

Program Chair General Chair Dr. G. Udayakumar, Professor and Head, Department of Civil Engineering Coordinators Dr. Arunkumar Bhat, Professor Mr. M. Janakaraj, Assistant Professor

Program Committee Publication Committee Dr. B. M. Mithun Dr. Anilkumar Mr. Shriram Marathe Mr. Shanmukha Shetty Mr. Thushar Shetty

Organizing Committee

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Web and Publicity Committee Dr. K. Radhakrishnan Ms. Thangamani Mr. Manjunath Registration Committee Dr. S. K. Mahadeve Gowda Mr. Sabyath Shetty Ms. Thanushree Hegde Hospitality Chair Mr. Y. R. Suresh Mr. Y. Umashankar Shetty Mr. Roshan Rai Finance Chair Dr. B. E. Bhojaraja Mr. Shaik Kabeer Ahmed Mr. A. Ranjith Food and Refreshments Mr. Gururaj Acharya Mr. Prashanth Kumar Accommodation and Transportation Committee Dr. Srinath K. Shetty Mr. M. Pushparaj Mr. Pradeep Karanth Program Venue Chairs Dr. Anilkumar Mr. Shriram Marathe Mr. Rakshith Kumar Shetty Mr. H. K. Prithviraj

Conference Advisory Committee Members Dr. Mukesh Kashyap, Senior Lecturer (Construction Management), School of Architecture, Design and the Built Environment, Nottingham Trent University, England Dr. G. L. Sivakumar Babu, Professor, IISc Bengaluru Dr. Dharamveer Singh, Associate Professor, IIT Bombay

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Organizing Committee

Dr. H. N. Ramesh, Professor and Principal, UVCE, Bengaluru Dr. Puttaraju, Professor and Principal, SJBIT, Bengaluru Dr. Varghese George, Professor and Head, Civil Engineering, NITK Surathkal Dr. Vipul Prakash, Professor, IIT Roorkee Dr. G. P. Chandradhara, Professor and Head, Construction Technology and Management, JSS S&T University, Mysuru Dr. N. Suresh, Professor and Head, Civil Engineering, and Director of Building Fire Research Centre (BFRC), NIE, Mysuru

Technical Advisory Committee Members Dr. M. C. Narasimhan, Professor, NITK Surathkal Dr. Katta Venkataramana, Professor, NITK Surathkal Dr. Shivashankar, Professor, NITK Surathkal Dr. A. U. Ravishankar, Professor, NITK Surathkal Dr. B. B. Das, Professor, NITK Surathkal Dr. J. Prashanth, Assistant Professor, NIT Silchar Dr. B. Umesh, Assistant Professor, NIT Warangal Dr. M. Kiran Kumar Shetty, Professor, Manipal Institute of Technology, Manipal Sri. V. Madhava Rao, Associate Professor, JSS S&T University, Mysuru Dr. N. C. Balaji, Assistant Professor, NIE Mysuru Dr. Nitendar Palankar, Associate Professor, KLS Gogte Institute of Technology, Belagavi Dr. Sanjeev Sangami, Associate Professor, Jain College of Engineering, Belagavi

List of Reviewers

Dr. Dr. Dr. Dr. Dr. Dr. Dr. Dr. Dr. Dr. Dr. Dr. Dr. Dr. Dr. Dr. Dr. Dr. Dr. Dr. Dr. Dr. Dr. Dr. Dr. Dr. Dr. Dr. Dr. Dr. Dr.

Kishore Kulkarni, Central Building Research Institute, Roorkee Basavaraju Manu, National Institute of Technology Karnataka Surathkal Bharathi Ganesh, NMIT Bangalore Katta Venkataramana, National Institute of Technology Karnataka Surathkal J. Prashanth, National Institute of Technology Silchar, Assam M. H. Prashant, National Institute of Technology Karnataka Surathkal H. Ramesh, National Institute of Technology Karnataka Surathkal S. Shrihari, National Institute of Technology Karnataka Surathkal A. U. Ravi Shankar, National Institute of Technology Karnataka Surathkal H. Ajith Hebbar, Alva’s Institute of Engineering and Technology, Moodbidri Akshatha Shetty, AJ Institute of Technology, Mangalore Allama Prabhu, Global Academy of Technology, Bangalore Anil Kumar, Nitte Mahalinga Memorial Institute of Technology, Nitte Arun Kumar Bhat, Nitte Mahalinga Memorial Institute of Technology, Nitte A. S. Balu, National Institute of Technology Karnataka Surathkal B. B. Das, National Institute of Technology Karnataka Surathkal B. E. Bhojaraja, Nitte Mahalinga Memorial Institute of Technology, Nitte C. M. Ravi Kumar, UBDT, Davangere A. Chandrashekhar, KVGCE, Sullia Chandre Gowda, Jyothi Institute of Technology, Bangalore H. Eramma, UBDT, Davangere Gangadhar Mahesh, National Institute of Technology Karnataka Surathkal Gautham Sarang, VIT Chennai Gopinath Nayak, Manipal Institute of Technology, Manipal B. Jagadeesha Pai, MIT Manipal K. Jayappa, Mangalore University B. M. Lekha, KVGCE, Sullia M. C. Narasimhan, National Institute of Technology Karnataka Surathkal Mahadeve Gowda, Nitte Mahalinga Memorial Institute of Technology, Nitte Manu, National Institute of Technology Karnataka Surathkal Mohan Kumar Chavan, Malnad Hassan ix

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List of Reviewers

Dr. H. S. Narashimhan, MCE, Hassan Dr. B. O. Naveen, NIE, Mysore Dr. G. M. Naveen, Government Engineering College, Chamarajanagara Dr. Nitendra Palankar, Gogte Institute of Engineering and Technology, Belgaum Dr. Parameshwar Hiremath, Basaveshwar Engineering College, Bagalkot Dr. Poornachandra Pandit, MIT Manipal Dr. K. Radhakrishnan, Nitte Mahalinga Memorial Institute of Technology, Nitte Dr. B. Radheshyam, St. Joseph, Vamanjoor Dr. C. Rajasekaran, National Institute of Technology Karnataka Surathkal Dr. Ramesh Manoli, Global Academy of Technology, Bangalore Dr. Sandeep Nayak, Vivekananda College of Engineering and Technology, Puttur Dr. D. M. Sangeetha, AJ Institute of Technology, Mangalore Dr. Sanjeev Sangami, Jain college of Engineering, Belagavi Dr. B. S. Santhosh, JSS Academy of Technical Education, Bangalore Dr. Santhosh M. Malkapur, Ramaiah University of Applied Sciences, Bengaluru Dr. Shruti A. Upadhyaya, USA Dr. N. J. Soumya, VCET, Puttur Dr. P. C. Srinivasa, Government College, Kushalnagar Dr. Subrahmanya I. Bhat, Chemistry, NMAMIT, Nitte Dr. Subrahmanya Kundapura, National Institute of Technology Karnataka Surathkal Dr. Suman Saha, University of Minho, Institute for Sustainability and Innovation in Structural Engineering (ISISE), Portugal Dr. Vadivuchezhian K, National Institute of Technology Karnataka Surathkal Dr. M. T. Venuraju, Malnad College of Engineering, Hassan Dr. B. M. Mithun, Nitte Mahalinga Memorial Institute of Technology, Nitte Mr. M. Manjunath, Nitte Mahalinga Memorial Institute of Technology, Nitte Mr. Prithvi Raj, Nitte Mahalinga Memorial Institute of Technology, Nitte Mr. Pushparaj A. Naik, Nitte Mahalinga Memorial Institute of Technology, Nitte Mr. A. Ranjith, Nitte Mahalinga Memorial Institute of Technology, Nitte Mr. Roshan Rai, Nitte Mahalinga Memorial Institute of Technology, Nitte Mr. Sabyath Shetty, Nitte Mahalinga Memorial Institute of Technology, Nitte Mr. Shaik Kabeer Ahmed, Nitte Mahalinga Memorial Institute of Technology, Nitte Mr. Shanmukha Shetty, Nitte Mahalinga Memorial Institute of Technology, Nitte Dr. Shreelaxmi Prashanth, Manipal Institute of Technology, Manipal Mr. Sundip Shenoy, Nitte Mahalinga Memorial Institute of Technology, Nitte Mr. Sushanth Bhandary, Nitte Mahalinga Memorial Institute of Technology, Nitte Mr. R. Thangamani, Nitte Mahalinga Memorial Institute of Technology, Nitte Mr. Y. R. Suresh, Nitte Mahalinga Memorial Institute of Technology, Nitte Prof. Aarathi S. Bhat, Chemistry, NMAMIT, Nitte

Preface

N.M.A.M. Institute of Technology organized International Conference on Emerging Trends in Engineering (ICETE 2019) on May 23 and 24, 2019, which is the 9th International Conference since 2011. For the year 2019, in order to focus on the specific issues associated with various engineering disciplines, the idea of a multi-conference platform had been mooted. International Conference on Emerging Trends in Engineering (ICETE 2019)—a multi-conference platform—will be a collection of several international conferences with the themes specific to various engineering streams. Besides, there will be an opportunity for students and research scholars of various branches of engineering and technology, and industrial professionals to deliberate, present and discuss research papers. This proceedings contains full research papers, experience reports and empirical study plans. All of these submissions went through a rigorous peer-review process commensurate with their track. In all, 148 research papers were submitted; each was reviewed by minimum of two experts, out of 148 papers 135 were accepted for conference only, and 63 papers were accepted for both conference and possible publication in lecture notes in civil engineering (Springer) which were accepted (an acceptance rate of 47%). Research papers were reviewed and ranked by the track chairs and discussed with the industry and practice chairs in order to ensure suitable sessions were available to run the same. Surathkal, India Surathkal, India Nitte, India Nitte, India

M. C. Narasimhan Varghese George G. Udayakumar Anil Kumar

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Contents

Construction and Structural Engineering Analysis of RCC Structures Subjected to Spatial Blast Loading . . . . . . Payal Kadam and Vidya Patil

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Effectiveness of Base Isolation Using Single Friction Pendulum in Plan Irregular Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . R. Sharika and Katta Venkataramana

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Review Paper on Behavior of Cold-Formed Steel Sections Under Axial Compression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Asim Bahadur, Kiran Shinde, and Vidya Patil

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Analysis of Anchorage Zone Stresses in Post-tensioned Concrete Girders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. D. Dipindas, M. H. Prashanth, and P. Lakshmy

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A Study on Influence of GGBFS as Binder on Bond Strength Behaviour of Reinforced Concrete . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V. P. Prashanth, H. M. Mahendra Kumar, and G. P. Chandradhara

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Comparative Studies on Flexural Strength of Conventional and Alkali-Activated Masonry Elements Designed to Field Mix . . . . . . . Sahithya S. Shetty, Shriram Marathe, and I. R. Mithanthaya

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The Impact of Buildability Factors on Formwork in Residential Building Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M. Sona

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Performance Evaluation of Deep Beams Using Self-compacting Concrete Subjected to Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . R. Manjunath, Mattur C. Narasimhan, and C. Bibesh Nambiar

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Performance Evaluation of Steel Fiber-Reinforced Deep Beams Using Self-compacting Concrete . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 R. Manjunath, Mattur C. Narasimhan, and Janagam Seismic Analysis of Open Ground Storey Building with Different Plan Configuration and Elevation Symmetry . . . . . . . . . . . . . . . . . . . . . . . . . 121 Gireesha Bhat and Thushar S. Shetty A Parametric Study on Soil-Structure Interaction of RC Building with Different Base Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 L. Lakshmi and C. M. Ravi Kumar Effect of Diaphragm Discontinuity on the Seismic Response of an RC Building . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157 Vincle Mable Vas, Prajwal Nagaraja, and Katta Venkataramana Study on Effects of Hooked-End Steel Fiber-Reinforced Concrete . . . . . 171 Anil Kumar, N. R. Pavan Prasad, and S. K. Sujith Seismic Behaviour and Comparison of Different Slab System Diagrid Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185 C. Rahul and J. K. Lokesh Graphene Oxide Incorporated Concrete for Rigid Pavement Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199 P. K. Akarsh and Arun Kumar Bhat Prediction of Effect of Geometrical Parameters in Trough Shape Folded Plate Roof Using ANN Modeling . . . . . . . . . . . . . . . . . . . . . . . . 221 Bhagwan Girish Shanbhag and Y. R. Suresh Analysis of RC Irregular Building According to Different Seismic Design Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239 Baburao Anuse and Kiran Shinde Study of Behaviour of High Rise Buildings with Diagrid Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249 Mangesh Vhanmane and Maheshkumar Bhanuse Constructive Scope on Implementation of Copper Slag as Replacement for Natural Fine Aggregate—An Overview . . . . . . . . . . . . 263 Y. T. Thilak Kumar, D. Arpitha, V. J. Sudarshan, C. Rajasekaran, and Nagesh Puttaswamy Assessment on Performance of Steel Slag and Processed Granulated Blast Furnace Slag as an Alternative for Fine Aggregate—An Assertive Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273 V. J. Sudarshan, D. Arpitha, Y. T. Thilak Kumar, C. Rajasekaran, and Nagesh Puttaswamy

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An Experimental Study on Self-remediating Bacterial Concrete . . . . . . 283 S. Girish, T. Soumya, and Sahana Girish Sorptivity as a Durability Index for Service Life Prediction of Self-compacting Concrete . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295 S. Girish, N. Ajay, and T. Soumya Strengthening of RCC Slab by Using Prestressed Carbon Fibre Reinforced Polymer Laminate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311 Vaibhav Jadhav and Santosh Mohite Performance-Based Economic Evaluation of Retrofitted Slabs with Different FRP’s and Different Configurations . . . . . . . . . . . . . . . . . 323 B. S. Shubhalakshmi, H. N. Jagannatha Reddy, R. Prabhakara, and Arjun Kasi Comparative Study on Behaviour of CFST and CES Columns Using ABAQUS Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333 Thripthi, A. Ranjith, A. Tanvi Rai, and Sahana Suresh Time-Invariant Reliability Analysis of RC T-Beam Bridge Girder—Limit State of Strength in Flexure . . . . . . . . . . . . . . . . . . . . . . 349 Ranjith A., K. Balaji Rao, A. Tanvi Rai, Thripthi, and K. Manjunath Vulnerability Assessment of Step Back and Set Back Buildings on Different Slopes Under Earthquake Loading . . . . . . . . . . . . . . . . . . . 373 Chidanand Bidnalamath, Sabyath Shetty, Pradeep Karanth, and Shanmukha Shetty Effect of Different Base Isolation Techniques in Multistoried RC Regular and Irregular Building . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 391 Prashant Sunagar, Aravind Bhashyam, Manish Shashikant, K. S. Sreekeshava, and Abhishek Kumar Chaurasiya Geotechnical Engineering and Transportation Engineering Performance Evaluation of Stone Mastic Asphalt Incorporating Sugarcane Bagasse Ash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 407 G. O. Ganesh and Roshan Rai Experimental Investigation on the Effect of Polyurethane Foam on Black Cotton Soil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 421 Anil Kumar, Hebbar Adithya, Kumara Amith, Shetty Akshar, and Rakshitha Development of Mobile Application for Computing SBC of Soil . . . . . . 433 Anil Kumar, Shivaleela, Amina Maureen, Abdulla Sahl, and Anees Anwar

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Performance of Alkali-Activated Mortar Mixes Containing Industrial Waste Materials as Binders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 447 B. M. Mithun, Nitendra Palankar, and Vaibhav Chate Effect of Landfill Leachate on Performance of Subgrade Soil . . . . . . . . 457 G. Manjunath, A. Aishwarya, I. Mallikarjun, P. Radha, and S. Sangami Measurement and Analysis of Noise Levels in the Sensitive Areas of Mysuru City, India . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 465 H. G. Vivek Prasad, Sachith Kothari, B. Manoj Kumar, and Sanjana Suresh Overlay Design of Flexible Pavements Using Benkelman Beam Deflection Method—A Case Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 475 Ashwini Prabhu, S. P. Arpith, K. K. Vahida, Dishanth Kumar, Arunkumar Bhat, and Anil Kumar Environmental Engineering and Water Resource Engineering Anaerobic Co-digestion of 2,4-Dichlorophenoxyacetic Acid with Starch Followed by Aerobic Post-treatment and Identification of Dominant Bacteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 495 G. B. Mahesh and Basavaraju Manu Removal of Heavy Metals from Synthetic Mine Drainage in Laboratory Scale Constructed Wetlands . . . . . . . . . . . . . . . . . . . . . . 507 S. Blesson, A. Naik Pushparaj, and Satoshi Soda Defluoridation of Groundwater Using Electrocoagulation Followed by Adsorption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 525 B. P. Deepthi, B. V. Shreyas, and K. N. Vishwanath Identification of Potential Sources Affecting Fine Particulate Matter Concentration in Delhi, India . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 543 K. Harsha, S. M. Shiva Nagendra, and Paresh Chandra Deka Removal of 2,4-D Herbicide from Water by Electrocoagulation Using Copper Electrodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 561 K. Sarika, K. Sneha, M. Shivani, B. Shefali, and S. Sangami Assessment of Meteorological Drought Return Periods Over a Temporal Rainfall Change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 573 Rajarshi Datta, Abhishek A. Pathak, and B. M. Dodamani An Experimental Investigation on Toe Stability for Vertical—Caisson Breakwaters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 593 V. Kumaran, Subba Rao, and Manu

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Experimental Studies on Geo-Synthetic Vertical Barrier Around the Dumpyard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 603 Nalini Rebello, R. Harikiran, Akarsh, Shrikanth Vasani, and Sayed Aseem Development of Water Filtration Unit Using PVA-Based Composite Membrane and Fly Ash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 611 Nalini Rebello, Mahima S. Rao, Melroy Royston D’Souza, S. M. Mahesha, and Vaishnavi T. Rajeev Surveying and Geographical Information Systems Temporal Crop Monitoring with Sentinel-1 SAR Data . . . . . . . . . . . . . 621 Shaik Salma and B. M. Dodamani Impacts of Dams on Sediment Yield and Coastal Processes Using SWAT and DSAS Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 633 K. Athira, Arunkumar Yadav, Basavanand M. Dodamani, and G. S. Dwarakish Generation of Intensity Duration Frequency Curve Using Daily Rainfall Data for Aghanashini River Watershed, Uttara Kannada . . . . 647 Shivakumar J. Nyamathi and H. K. Yashas Kumar Evaluation of CHIRPS Satellite Rainfall Datasets Over Kerala, India . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 655 P. Divya and Amba Shetty Flood Inundation Mapping of Harangi River Basin, Kodagu, Using GIS Techniques and HEC-RAS Model . . . . . . . . . . . . . . . . . . . . . 665 M. R. Devanand and Subrahmanya Kundapura Hydrologic Modelling of Flash Floods and Their Effects . . . . . . . . . . . . 679 An Rose Paul and Subrahmanya Kundapura Hydrological Modeling of Stream Flow Over Netravathi River Basin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 695 S. Ashish, Subrahmanya Kundapura, and Vadivuchezhian Kaliveeran Crop Suitability Analysis for Kabini Command Area Using RS and GIS Techniques—A Multi-criteria Approach . . . . . . . . . . . . . . . . . 715 M. Shivaswamy, A. S. Ravikumar, and B. L. Shivakumar High-Resolution Mapping of Soil Properties Using AVIRIS-NG Hyperspectral Remote Sensing Data—A Case Study Over Lateritic Soils in Mangalore, India . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 735 Mandar Mohan Chitale and Subrahmanya Kundapura A Statistical Approach for Comparison of Secondary Precipitation Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 753 Rajesh Kommu, Subrahmanya Kundapura, and Venkatesh Kolluru

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Contents

Identification of the Best-Fit Probability Distribution and Modeling Short-Duration Intensity-Duration-Frequency Curves—Mangalore . . . . 765 C. Varghese Femin and K. Varija Monitoring Land Use and Land Cover Changes in Coastal Karnataka . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 785 Mundlamuri Satish Kumar, Venkatesh Kolluru, S. B. Gowthami, N. A. Anjita, N. Nayana, Linda Regi, and G. S. Dwarakish Water Level Retrieval and Water Body Mapping: A Case Study of Nagarjuna Sagar Reservoir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 797 Nalluri Ahalya and H. Ramesh Impact of Rainfall on Land Use and Land Cover Analysis . . . . . . . . . . 809 B. N. Suma and C. V. Srinivasa Rainfall Trend Analysis in Coastal Region of Karnataka . . . . . . . . . . . . 823 S. Ashwin, K. Prashanth Kumar, and D. C. Vinay A Study on Shore-Line Dynamics During and Post-construction of Breakwaters in Kasaragod Fishing Harbour . . . . . . . . . . . . . . . . . . . 835 Vadelu Krishna Chaitanya, T. Nasar, and Kunhimammu Paravath Hydrogeochemical Evaluation for Developmental Activity in part of Belma Microwatershed, Dakshina Kannada District, Karnataka . . . . 853 R. Thangamani, K. Radhakrishnan, and K. V. Sindhu Assessment of Solar Power Potential Mapping in Telangana State Using GIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 865 Manish S. Dharek, Prashant C. Sunagar, Manjunath V. Kadalli, K. S. Sreekeshava, and Anant G. Pujar

About the Editors

Dr. M. C. Narasimhan is a proud alumnus of University BDT college of Engineering, Davangere, India [B.E (Civil Engg) - 1982]. He obtained his masters and doctoral degree from Indian Institute of Technology Madras, India, during the years 1985 and 1993, respectively. He started his teaching career at the National Institute of Technology Karnataka (NITK) [formally, Karnataka Regional Engg. College, KREC] as a lecturer in the Department of Applied Mechanics and Hydraulics in the year 1985 and was promoted as a professor in the Department of Civil Engineering in the year 2002. His research interests are in the areas of concrete technology, special concretes, structural behavior of RCC, steel and composite constructions and numerical methods in structural analysis. He has completed number of R&D and consultancy projects in his department. He has guided more than fifty post graduate students for their dissertations and eight students for their doctoral thesis. He has large number of research publications to his credit- either published in leading journals or presented and included in proceedings of reputed international conferences. He is also a life member of leading professional organisations like Institution of Engineers (India), Indian Cement Institute, Association of consulting civil engineers, Indian Society for Technical Education and Indian Society for Earthquake Technology. Dr. Varghese George Professor and Head in the Department of Civil Engineering (2017–19). He pursued his B.Sc. (Engineering) Degree from College of Engineering, Trivandrum, in the year 1984, M.Tech (Transportation Systems Engineering) from IIT Kanpur in the year 1986, and Ph.D (Transportation Engineering) from IIT Bombay in the year 1999. He served as the Associate Dean (Research and consultancy) in NITK Surathkal during 2010–13, and as the Head of Department of Civil Engineering, NITK, Surathkal during 2017–19. He has more than 33 years of teaching experience. Dr. Varghese George is a life member of professional bodies like the Indian Society for Technical Education (ISTE), Indian Roads Congress (IRC), Coorg and South Kanara Engineer’s Assn and the Institute of Urban Transport (IUT), and is a Fellow of the Institution of Engineers (India). He is also an Associate member of the ASCE, USA. He has published 20 research xix

xx

About the Editors

papers in International Journals, 22 papers in National journals, and 20 papers in International Conferences. He has guided 5 Doctoral Research students till date. His areas of expertise include urban transport planning, traffic engineering, road safety audit, porous friction courses, warm mix asphalt, pavement evaluation and monitoring, ground improvement, genetic algorithm & ANN applications, town panning and architecture, surveying, and green building. Dr. G. Udayakumar Former Professor and Head of Civil Engineering Department in N.M.A.M. Institute of Technology, Nitte. He obtained his B.E. (Civil Engineering) from Mysore University, M.Tech (Hydraulics and Water Resources Engineering) from Mangalore University and Ph.D (Water conservation) from NITK, Surathkal. He has 32 years of teaching experience and served as the Chief Project Leader of EDC for 3 years from 2013 to 2016 at NMAM Institute of Technology, Nitte. Dr. Udayakumar G is the member of professional bodies like ISTE, MIE and IAHS. He also served as a member of BOS and BOE in Mangalore University and VTU, Belgaum. He has published 19 research papers in National, International journals and conferences. He has guided 23 Under Graduate projects, 6 Post-Graduate students, 1 Doctoral student and 1 Post-Doctoral student. His areas of interest includes hydrology and water resources engineering, water conservation, engineering mechanics, strength of materials, fluid mechanics, hydraulics and hydraulic machines and groundwater engineering. Dr. Anil Kumar Assistant Professor in the Department of Civil Engineering. He pursued his B.E (Civil Engineering) from Nitte Mahalinga Memorial Institute of Technology, Nitte in the year 2008, M.Tech (Geo-Technical Engineering) from National Institute of Technology, Surathkal in the year 2010 and Ph.D (Geo-Technical Engineering) from National Institute of Technology, Surathkal in the year 2018. He has more 10 years of teaching experience. Dr. Anil is the member of professional bodies like LM-ISTE, SM-ASCE, SM-IRC. He has published 19 research papers in International Journals and 3 papers in National journals and 6 papers in International Conferences in the recent years. He has guided 7 PostGraduate Students and 18 Under-Graduate students. His areas of expertise include Geotechnical Engineering, Ground improvement techniques, Sub-surface exploration, Pavement evaluation and monitoring, and deep foundations.

Construction and Structural Engineering

Analysis of RCC Structures Subjected to Spatial Blast Loading Payal Kadam and Vidya Patil

Abstract The principle of building design is to achieve the assigned objectives under the prescribed demand. Cases of large-scale damages to structures are due to unpredictable, higher-level loading, arising out of environmental loading; blast loading is one of them. The purpose of this research is to calculate blast parameters by analytical approach and obtain the pressure variation on different faces of building using IS:4991-1968. Three explosion weights (100, 500 and 1000 kg) are exploded in three different standoff distances (15, 30 and 45 m) and at 0, 6 and 12 m vertical in air. Blast parameters and pressure variation on different faces of building are calculated for different explosive weights and respective distances. Keywords Explosion · Terrorist attack · Blast parameter · Spatial blast loading

1 Introduction In last few decades, tremendous damages due to extreme levels of unpredictable loading have been observed. Often they are due to blast loads. The vulnerability assessment of earthquake-resistant building structures is rather old, and most of the knowledge on this subject has been accumulated during the past fifty years. Similarity and dissimilarity of design objectives under these two loadings are to protect/resist the structural and non-structural performance in the predicted manner. An earthquakeresistant building structure is allowed to take advantage of ductility during severe earthquake loading; however, the same structures do not take too much ductility under large blast loading. The ultimate goal is that the structure which is most likely to be a target of terrorist attacks should be protected from the blast effect. The dynamic response of the structure to blast loading is complex to analyse, because of the nonlinear P. Kadam (B) · V. Patil Department of Civil Engineering, Annasaheb Dange College of Engineering & Technology, Ashta, India e-mail: [email protected] © Springer Nature Singapore Pte Ltd. 2021 M. C. Narasimhan et al. (eds.), Trends in Civil Engineering and Challenges for Sustainability, Lecture Notes in Civil Engineering 99, https://doi.org/10.1007/978-981-15-6828-2_1

3

4

P. Kadam and V. Patil

behaviour of the materials as well as the geometry. Hence, analyses and design of structures for blast loading require detailed knowledge of the phenomena of blast.

1.1 Explosion An explosion is defined as rapid and sudden release of energy. Explosive materials can be classified according to their physical state as solids, liquids or gases. Solid explosives are mainly high explosives for which blast effect is best known. Materials such as mercury fulminates and lead azide are primary explosives. Secondary explosives are those create blast wave which can result in widespread damage to the surroundings, e.g. trinitrotoluene and ammonium nitrate fuel oil.

2 Literature Review Eskew and Jang [1] studied the “Impacts and Analysis for Buildings under Terrorist Attacks”, which gives the impact from a terrorist attack against a structure can be devastating, causing damage to nearby people, and to the structure itself, up to a progressive collapse. Apart from this, Kashif and Verma [2] studied the “Effect of Blast on RCC frame structures” which provides guidance for consideration of column joints from explosive charge. Dragonic and Sigmun [3] studied a manual titled “Blast loading on structures”, which contains step-by-step procedure to analysis of structure subjected to blast loading manually and by using SAP with reference of UFC code. TM 5-1300 (UFC 3-340-02) [4] is a manual titled “structures to resist the effects of accidental explosions”, which provides guidance to designers the stepto-step analysis and design procedure. Ngo et al. (The University of Melbourne, Australia) [5] studied the “Blast loading and Blast Effects on Structures”, which gives an overview on the analysis and design of structures subjected to blast load phenomenon for understanding the blast loads and dynamic response of various structural elements. This study helps for the design consideration against extreme events such as bomb blast and high-velocity impacts. Koccaz et al. [6] studied the “architectural and structural design for blast resistant buildings”, which gives us some knowledge about the design parameters of blast-resisting buildings. Lu et al. [7] studied the “response of model structure under simulated blast-induced ground excitations”, which gives an overview of understanding the performance of model structure under blasting. Remennikov [8] studied the methods for predicting bomb blast effects on buildings.

Analysis of RCC Structures Subjected to Spatial Blast Loading

5

3 Objectives • To understand blast loading concept. • To study blast parameters using guidelines provided by IS 4991-1968. • To study pressure variation on different faces of building.

4 Problem Formulation The importance of present research work is to calculate blast parameters and pressure variation on different faces of building using guidelines provided by IS 4991-1968.

5 Methodology Details of building selected for analysis are as follows: Four-storey RC building frame of 12 m × 12 m size. Height of each storey is 3.00 m (Figs. 1 and 2).

5.1 Description of Data for Trial-IA • • • • •

Size of building 12 m × 12 m. Horizontal distance of building from the origin of explosion, R = 15 m. Charge height, H c = 0 m (ground explosion). Explosive weight W = 1000 kg. Scaled distance Z = R/wˆ1/3 = 15/1ˆ1/3 = 15 m (Fig. 3).

Fig. 1 Plan of selected building

4 4m

4m

4m 3

4m 2 4m 1

6

P. Kadam and V. Patil

Fig. 2 Distance of each column joint from origin

3rd 2nd 1st G

Fig. 3 Explosive charge on ground

15m

5.1.1

Determination of Blast Parameters

Determination of free-field blast wave parameters at different points from IS code IS: 4991-1968. Peak positive incident pressure (Pso ), Mach number (M), Duration of positive phase of blast pressure (t o ), duration of equivalent triangular phase (t d ), peak dynamic pressure (qo ), peak reflected overpressure (Pro ), velocity of sound in air (a), shock front velocity (U), drag coefficient (C D ), transit time (t t ). (1) From Table 1 of IS: 4991-1968 for Z11 = Z14 = 16.43 m; (2) Pso = 6.57 kg/cm2 , M = 5.154, t o = 10.215 ms, t d = 6.243 ms, qo = 8.065 kg/cm2 . (3) Pro = 32.49 kg/cm2 , a = 344 m/s, U = M × a = 5.154 × 344 = 0.88 m/ms. Pressures acting on the building with determination of equivalent time: (1) Front wall peak reflected overpressure, Pro = 32.49 kg/cm2 Table 1 Radial distance of column joints from explosive charge Storeys (j)

Joints (i) 1 (m)

2 (m)

3 (m)

4 (m)

Ground storey

16.43

15.42

15.42

16.43

First storey

17.23

16.28

16.28

17.23

Second storey

18.49

17.60

17.60

18.49

Third storey

20.12

19.31

19.31

20.12

Analysis of RCC Structures Subjected to Spatial Blast Loading

7

Table 2 Positive peak reflected overpressure for various faces Face

Positive pressures (kg/cm2 )

Equivalent time (ms)

Front wall

32.49

6.243

Side wall and roof

4.957

6.243

(2) For roof and side faces, P = Pso + C D · q0 = 6.57 + (−0.2 × 8.065) = 4.957 kg/cm2 (3) For determination of duration of equivalent triangular phase is the smaller of t d and t c tc = 3S/U or td . . . . . . whichever is less = 3 × 6/0.88 = 20.45 or 6.243 ms = 6.243 ms where S = H or B/2 whichever is less therefore, S = less of 12 and 12/2 = 6.0 m. (4) Check for requirement of consideration of blast effect on rear side of building. If t t and t r > t d , then no need to consider pressure on backside of building. tt =L/U = 12/0.88 = 13.64 ms > td tr = 4S/U = 4 × 6/0.88 = 27.27 ms > td Here, no need to consider pressure on the backside of building (Table 2).

5.2 Description of Data for Trial-IB • • • • •

Size of building 12 m × 12 m Horizontal distance of building from the origin of explosion, R = 15 m Charge height, H c = 6 m (spatial explosion) Explosive weight W = 1000 kg Scaled distance Z = WR1/3 = 15/10001/3 = 15 m (Fig. 4 and Table 3).

5.3 Description of Data for Trial-IC • • • •

Size of building 12 m × 12 m Horizontal distance of building from the origin of explosion, R = 15 m Charge height, H c = 12 m (spatial explosion) Explosive weight W = 1000 kg

8

P. Kadam and V. Patil

Fig. 4 Explosive charge on at 15 m(H)/6 m

6m 15m

Table 3 Radial distance of column joints from explosive charge Storeys (j)

Joints (i) 1 (m)

2 (m)

3 (m)

4 (m)

Ground storey

16.43

15.42

15.42

16.43

First storey

16.15

15.13

15.13

16.15

Second storey

16.43

15.42

15.42

16.43

Third storey

17.23

16.28

16.28

17.23

• Scaled distance Z =

R W 1/3

= 15/10001/3 = 15 m (Fig. 5 and Table 4).

Similarly, blast parameters are calculated for all the points. Fig. 5 Explosive charge on at 15 m(H)/6 m

12m 15m

Table 4 Radial distance of column joints from explosive charge Storeys (j)

Joints (i) 1 (m)

2 (m)

3 (m)

4 (m)

Ground storey

16.43

15.42

15.42

16.43

First storey

16.15

15.13

15.13

16.15

Second storey

16.43

15.42

15.42

16.43

Third storey

17.23

16.28

16.28

17.23

Analysis of RCC Structures Subjected to Spatial Blast Loading

9

6 Results and Discussion See Tables 5, 6 and 7.

7 Conclusion • As above said, the peak reflected pressure is much greater than the peak positive pressure on all the faces of the building; so the effect of the reflected pressure is more on the front face (side where explosion occurred) of the building or structure. • In case of side face and roof of the building, the reflected pressure is less than the peak positive pressure. So the effect of the reflected pressure on these faces is low when compared with the front face. • With the variation of ground zero points, i.e. 0, 6 and 12 m, the intensity of reflected pressure and side-roof overpressure increases, so we can conclude that if blast is occurring in air, more pressure intensity induces.

30

0

15

6

0

12

6

Ground zero (m)

Standoff distance (m)

64.66 64.73 64.94

2

3

4

65.76

4 64.73

65.28

3

1

64.94

32.37

4

2

32.50

3 64.73

32.92

1

33.59

32.92

4

2

32.50

1

32.37

3

34.52

4

2

33.59

3 32.50

32.92

1

32.50

2

Scaled distance (m)

1

Storey nos.

Table 5 Blast parameters for explosive charge 100 kg

17.54

17.51

17.50

17.51

17.63

17.57

17.54

17.51

11.38

11.42

11.55

11.74

11.55

11.42

11.38

11.42

11.99

11.74

11.55

11.42

t o (ms)

Blast parameters

13.19

13.16

13.15

13.16

13.31

13.24

13.19

13.16

7.48

7.50

7.56

7.74

7.56

7.50

7.48

7.50

8.23

7.74

7.56

7.50

t d (ms)

0.041

0.042

0.042

0.042

0.04

0.041

0.041

0.042

0.47

0.46

0.44

0.41

0.44

0.46

0.47

0.46

0.37

0.41

0.44

0.46

q0 (kg/cm2 )

0.80

0.82

0.81

0.82

0.78

0.79

0.80

0.82

3.61

3.58

3.47

3.31

3.47

3.58

3.61

3.58

3.10

3.31

3.47

3.58

Pro (kg/cm2 )

(continued)

0.33

0.33

0.34

0.33

0.326

0.33

0.33

0.33

1.05

1.04

1.03

0.99

1.03

1.04

1.05

1.04

0.95

0.99

1.03

1.04

Pso (kg/cm2 )

10 P. Kadam and V. Patil

45

Standoff distance (m)

Table 5 (continued)

12

6

97.14 97.00 96.96

3

4

97.14

4

2

97.00

3 97.37

96.96

1

97.00

97.70

4

2

97.37

3

1

97.14

2

64.66

4 97.00

64.73

3

1

64.94

2

0

65.28

1

12

Scaled distance (m)

Storey nos.

Ground zero (m)

21.12

21.12

21.12

21.13

21.12

21.12

21.12

21.12

21.14

21.13

21.12

21.12

17.50

17.51

17.54

17.57

t o (ms)

Blast parameters

16.54

16.50

16.56

16.59

16.56

16.50

16.54

16.50

16.64

16.59

16.56

16.50

13.15

13.16

13.19

13.24

t d (ms)

0.013

0.013

0.013

0.013

0.013

0.013

0.013

0.013

0.012

0.013

0.013

0.013

0.042

0.042

0.041

0.041

q0 (kg/cm2 )

0.407

0.410

0.410

0.405

0.410

0.410

0.407

0.410

0.404

0.405

0.410

0.410

0.81

0.82

0.80

0.79

Pro (kg/cm2 )

0.182

0.182

0.180

0.180

0.180

0.182

0.182

0.182

0.179

0.180

0.180

0.182

0.34

0.33

0.33

0.33

Pso (kg/cm2 )

Analysis of RCC Structures Subjected to Spatial Blast Loading 11

30

0

15

6

0

12

6

Ground zero (m)

Standoff distance (m)

64.66 64.73 64.94

2

3

4

65.76

4 64.73

65.28

3

1

64.94

32.37

4

2

32.50

3 64.73

32.92

1

33.59

32.92

4

2

32.50

1

32.37

3

34.52

4

2

33.59

3 32.50

32.92

1

32.50

2

Scaled distance (m)

1

Storey nos.

Table 6 Blast parameters for explosive charge 500 kg

17.54

17.51

17.50

17.51

17.63

17.57

17.54

17.51

11.38

11.42

11.55

11.74

11.55

11.42

11.38

11.42

11.99

11.74

11.55

11.42

t o (ms)

Blast parameters

13.19

13.16

13.15

13.16

13.31

13.24

13.19

13.16

7.48

7.50

7.56

7.74

7.56

7.50

7.48

7.50

8.23

7.74

7.56

7.50

t d (ms)

0.041

0.042

0.042

0.042

0.04

0.041

0.041

0.042

0.47

0.46

0.44

0.41

0.44

0.46

0.47

0.46

0.37

0.41

0.44

0.46

q0 (kg/cm2 )

0.80

0.82

0.81

0.82

0.78

0.79

0.80

0.82

3.61

3.58

3.47

3.31

3.47

3.58

3.61

3.58

3.10

3.31

3.47

3.58

Pro (kg/cm2 )

(continued)

0.33

0.33

0.34

0.33

0.326

0.33

0.33

0.33

1.05

1.04

1.03

0.99

1.03

1.04

1.05

1.04

0.95

0.99

1.03

1.04

Pso (kg/cm2 )

12 P. Kadam and V. Patil

45

Standoff distance (m)

Table 6 (continued)

12

6

57.03 56.80 56.72

3

4

57.03

4

2

56.80

3 57.43

56.72

1

56.80

57.97

4

2

57.43

3

1

57.03

2

64.66

4 56.80

64.73

3

1

64.94

2

0

65.28

1

12

Scaled distance (m)

Storey nos.

Ground zero (m)

28.12

28.14

28.20

28.28

28.20

28.14

28.12

28.14

28.39

28.28

28.20

28.14

17.50

17.51

17.54

17.57

t o (ms)

Blast parameters

20.82

20.86

20.95

20.97

20.95

20.86

20.82

20.86

21.00

20.97

20.95

20.86

13.15

13.16

13.19

13.24

t d (ms)

0.063

0.063

0.062

0.061

0.062

0.063

0.063

0.063

0.059

0.061

0.062

0.063

0.042

0.042

0.041

0.041

q0 (kg/cm2 )

1.02

1.02

1.01

1.00

1.01

1.02

1.02

1.02

0.98

1.00

1.01

1.02

0.81

0.82

0.80

0.79

Pro (kg/cm2 )

0.405

0.405

0.405

0.401

0.405

0.405

0.405

0.405

0.386

0.401

0.405

0.405

0.34

0.33

0.33

0.33

Pso (kg/cm2 )

Analysis of RCC Structures Subjected to Spatial Blast Loading 13

30

0

15

6

0

12

6

Ground zero (m)

Standoff distance (m)

30.07 30.22 30.66

2

3

4

32.37

4 30.22

31.38

3

1

30.66

15.13

4

2

15.42

3 30.22

16.28

1

17.60

16.28

4

2

15.42

1

15.13

3

19.31

4

2

17.60

3 15.42

16.28

1

15.42

2

Scaled distance (m)

1

Storey nos.

Table 7 Blast parameters for explosive charge 1000 kg

23.37

23.08

22.98

23.08

24.53

23.86

23.37

23.08

9.57

9.71

10.14

10.80

10.14

9.71

9.57

9.71

13.35

10.80

10.14

9.71

t o (ms)

Blast parameters

15.59

15.46

15.41

15.46

16.12

15.81

15.59

15.46

5.47

5.64

6.15

6.94

6.15

5.64

5.47

5.64

8.12

6.94

6.15

5.64

t d (ms)

0.550

0.572

0.58

0.572

0.469

0.517

0.550

0.572

10.43

9.90

8.34

5.94

8.34

9.90

10.43

9.90

4.09

5.94

8.34

9.90

q0 (kg/cm2 )

4.04

4.15

4.18

4.15

3.61

3.86

4.04

4.15

40.77

38.93

33.45

25.05

33.45

38.93

40.77

38.93

18.33

25.05

33.45

38.93

Pro (kg/cm2 )

(continued)

1.14

1.16

1.17

1.16

1.06

1.11

1.14

1.16

5.78

5.60

5.05

4.21

5.05

5.60

5.78

5.60

3.44

4.21

5.05

5.60

Pso (kg/cm2 )

14 P. Kadam and V. Patil

45

Standoff distance (m)

Table 7 (continued)

12

6

45.44 45.14 45.04

3

4

45.44

4

2

45.14

3 45.93

45.04

1

45.14

46.61

4

2

45.93

3

1

45.44

2

30.07

4 45.14

30.22

3

1

30.66

2

0

31.38

1

12

Scaled distance (m)

Storey nos.

Ground zero (m)

31.26

31.30

31.40

31.56

31.40

31.30

31.26

31.30

31.79

31.56

31.40

31.30

22.98

23.08

23.37

23.86

t o (ms)

Blast parameters

21.61

21.65

21.76

21.94

21.76

21.65

21.61

21.65

22.19

21.94

21.76

21.65

15.41

15.46

15.59

15.81

t d (ms)

0.142

0.141

0.138

0.134

0.138

0.141

0.142

0.141

0.128

0.134

0.138

0.141

0.58

0.572

0.550

0.517

q0 (kg/cm2 )

1.66

1.65

1.63

1.60

1.63

1.65

1.66

1.65

1.55

1.60

1.63

1.65

4.18

4.15

4.04

3.86

Pro (kg/cm2 )

0.605

0.604

0.595

0.586

0.595

0.604

0.605

0.604

0.568

0.586

0.595

0.604

1.17

1.16

1.14

1.11

Pso (kg/cm2 )

Analysis of RCC Structures Subjected to Spatial Blast Loading 15

16

P. Kadam and V. Patil

References 1. Eskew E, Jang S, Department of Civil and Environmental Engineering, University of Connecticut (2012) Impacts and analysis for buildings under terrorist attacks. Ppr 2012.11.16. 2. Kashif Q, Verma MB (2014) Effect of blast on RCC frame structures. IJETAE 4(11) 3. Dragonic H, Sigmund V (2012) Blast loading on structures 643–652 4. TM 5-1300(UFC 3-340-02) U.S. Army Corps of Engineers (1990) Structures to resist the effects of accidental explosions. U.S. Army Corps of Engineers, Washington, D.C., (also Navy NAVFAC P200-397 or Air Force AFR 88-22) 5. Ngo T, Mendis P, Gupta A, Ramsay J (2007) Blast loading and blast effects on structure. The University of Melbourne, Australia 6. Koccaz Z, Sutcu F, Torunbalci N, Architectural and structural design for blast resistant buildings. 14 WCEE-05-01-0536 7. Lu Y, Hao H, Ma G, Zhou Y, Response of model structure under simulated blast-induced ground excitations. 12 WCEE-2000-0972 8. Remennikov AM (2003) A review of methods for predicting bomb blast effects on buildings. J Battlefield Technol 6(3):155–161

Effectiveness of Base Isolation Using Single Friction Pendulum in Plan Irregular Structures R. Sharika and Katta Venkataramana

Abstract Base isolation is found to be a very efficient earthquake-resistant construction method. When base isolation is introduced, the transfer of large amount of inertia forces is prevented by the moving action of an isolator during an earthquake. The application of base isolator in regular buildings is done from long before, but the usage and effectiveness of base isolation in irregular buildings are a topic which needs more research. In this study, single friction pendulum isolator is used to isolate the buildings and the effectiveness of isolators is discussed in regular as well as plan irregular buildings. Modal analysis and time history analysis using Chi-Chi earthquake accelerogram data is done. Time period obtained from modal analysis and the results of time history analysis, such as base shear, storey acceleration and storey drift of regular, as well as plan irregular buildings are compared. The time period is found to increase significantly and base shear, acceleration and storey drift are decreased significantly with the application of single friction pendulum isolator. Also, the effectiveness of isolator got reduced with the introduction of irregularity in the structure. Keywords Base isolation · Single friction pendulum isolator · Modal analysis · Time history analysis · Accelerogram

1 Introduction The aim of earthquake-resistant construction is not to achieve complete protection of a structure which is practically impossible but to build structures which gives comparatively better performance than its conventional counterparts. When a building is made earthquake resistant, the cost involved is usually higher than conventional buildings. But the fact that such buildings would require almost no repairs after being subjected to a moderate earthquake is an added advantage which justifies the R. Sharika (B) · K. Venkataramana Department of Civil Engineering, National Institute of Technology Karnataka, Surathkal, Surathkal, Mangalore, Karnataka, India e-mail: [email protected] © Springer Nature Singapore Pte Ltd. 2021 M. C. Narasimhan et al. (eds.), Trends in Civil Engineering and Challenges for Sustainability, Lecture Notes in Civil Engineering 99, https://doi.org/10.1007/978-981-15-6828-2_2

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R. Sharika and K. Venkataramana

initial expense incurred. The main idea behind seismic design of structure is to make sure that a structure subjected to an earthquake has less storey drift and less floor acceleration. The problem associated with inter-storey drift and floor acceleration is that they are contradictory to each other. A stiffer structure would mean lesser drift but more acceleration and vice versa for a flexible structure. This is where base isolation comes into picture. Base isolation is one of the few techniques that permit lesser acceleration at lesser drift. The reason for seismic damage is due to the inertia of the structure that is above the ground which refuses to move in accordance with the ground motion. This inertia results in massive forces being transmitted to the structure. The basic theory behind base isolation is to modify the response of a structure or building in order to transmit minimal or no motion from the moving ground to the structure above. In a practical system, this complete separation cannot be achieved. The advantage of using a base isolator is that it increases the time period of a building. This helps in mitigating the effects of possible resonance and improves the seismic behaviour of a structure. Base isolators refer to the ones that are present under the structure. Professor John Milne (1850–1913) often called as the father of modern seismology, conducted mind-boggling research in the design of earthquake-resistant structure. He was the first to have submitted a paper on seismic isolation techniques which were carried out using cast iron balls and a concave saucer like plate. After numerous trials, he came up with a design that was both seismically resistant as well as safe against wind loads. Later, elastomeric bearings were developed using vulcanized rubber, reinforced with steel plates. These bearings were characterized by high vertical stiffness and high lateral flexibility. Soon the concept of bearing isolator was extended and sliding isolators came into being. Sliding isolator is the second common type of isolator. The controlling parameter here is the coefficient of friction of the sliding surface, i.e., the lower the coefficient of friction lower is the shear that is transmitted onto the structure. But one major drawback is that it does not have means of a restoring force. In order to overcome this drawback, an isolator with a curvature has been proposed. This is known as a sliding friction pendulum isolator as the movement is analogous to that of an oscillating pendulum. Fan et al. [1] and Su et al. [2, 3]made comparative studies on the various types of isolators such as pure friction base isolator, laminated rubber bearing, rubber bearing French system, New Zealand system, resilient friction base isolator, Electricite de France isolator and sliding resilient friction isolator. The major conclusion from their studies was that the friction isolators effectively reduce the transmitted acceleration with limited slip displacements. Liauw et al. [4] studied the combined effects of horizontal and vertical motions of actual earthquakes on structures isolated using sliding base and arrived to a conclusion that they are very much effective in suppressing the seismic risk of a structure. Mokha and Constantinou [5] conducted a shake table experiments on a six-storey building equipped with friction pendulum isolator and found out that the isolated system under elastic conditions, performed six times better than that of a fixed base system in terms of peak table acceleration. The suitability of SAP2000 for analysing the structures isolated using friction pendulum isolator was recognized by Scheller and Constantinou [6]. Their studies covered a

Effectiveness of Base Isolation Using Single Friction Pendulum …

19

vast domain and proved the applicability and reliability of SAP2000. Base isolation of regular buildings was discussed by many but the performance of isolator in irregular structures was least explored. Naveen et al. [7] studied the seismic response of base isolation system established in multi-storey mass irregular buildings and it was found that, inter storey drifts for mass irregular buildings are comparatively larger thus mass irregularity reduced the effectiveness of base isolation. Parma and Hiremath [8] extended their study into various aspects such as vertical and horizontal irregularities of structures. They observed that the effectiveness of isolator is found to be reducing from regular buildings to vertical irregular buildings and it is least effective in the case of plan irregular building. Since the studies about irregular buildings with isolators are very less [9, 10], extensive research is necessary in the field of irregular isolated buildings. The demand for such research is high because very often the buildings actually constructed in a site may not be regular due to various constraints. Present study attempts to investigate the extent of reduction in effectiveness of single friction pendulum (SFP) isolator with the introduction of plan irregularity in structures. The friction pendulum system proposed by Andrade and Tuxworth [11] is used in the study as isolator for regular and plan irregular buildings. The comparison of performance of isolator has been facilitated by performing modal analysis as well as time history analysis using component 0 of the Chi-Chi Earthquake of September 25, 1999 at 23:52:00 UTC (Station: TCU129 Taichung, Taiwan) in SAP2000.

2 Single Friction Pendulum System (SFP) The single friction pendulum system (SFP) is a patented device with spherical sliding surface which has been extensively used. The coefficient of friction of the bearing resists the service loads. Once the coefficient of friction is exceeded, the movement of articulated slider along the concave surface is initiated. The vertical movement of mass is also present with this lateral travel which in turn provides a restoring force. This SFP system is used as the isolator in the current study and is shown in Fig. 1. Fig. 1 Scheme of the single friction pendulum system (SFP)

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R. Sharika and K. Venkataramana

2.1 Concept of SFP The concept behind the working of single friction pendulum bearing is as same as a simple pendulum. During the event of an earthquake, the movement of the articulated slider takes place along the concave surface resulting in small simple harmonic motion of the structure as shown in Fig. 2. Thereby, the natural period of the structure is increased by the SFP bearings. The frictional interface filters out the destructive effect of an earthquake and also acts as a damping system. The concave surface of the bearings along with gravity imparts re-centring capability to the system, by which the structure can centre itself, if any displacement had taken place. The centre position and displaced position of SFP are shown in Fig. 3.

3 Model Structure Configuration In this study, structures with three different types of plan configurations are modelled in SAP2000, one building with regular plan, another with an L-shaped plan and the last one with a C-shaped plan. All the three buildings are four storied with a storey height of 3 m each. Figure 4 shows the plan configurations of three types of buildings. The geometric properties of the building models chosen for the study are presented in Table 1.

Fig. 2 Concept of working of single friction pendulum system (SFP)

Fig. 3 Motion of single friction pendulum system (SFP)

Effectiveness of Base Isolation Using Single Friction Pendulum …

21

Fig. 4 Plan configurations of various buildings Regular Building

L-Shaped Building

C-Shaped Building

Table 1 Geometric properties of buildings

Sl. No.

Geometric properties of buildings

1

Number of storeys

G+3

2

Height of floors

3m

3

Beam dimensions

230 mm × 450 mm

4

Column dimensions

450 mm × 450 mm

5

Slab thickness

150 mm

6

Partition wall thickness

230 mm

7

Parapet wall thickness

100 mm

8

Grade of steel

415

9

Grade of concrete

M30 (M20 for slab)

4 Loads on Structures The various loads to be considered play an important role in the design of isolator. Based on the method suggested by Andrade and Tuxworth [11], isolator under each column is designed according to the load to that particular column after considering all the load cases. The dead load coming to the structure is determined according to IS:875 (Part I). Self-weights of concrete and 230 mm masonry wall are taken

22

R. Sharika and K. Venkataramana

25 and 20 kN/m3 , respectively. For 100 mm parapet wall, the self-weight is taken as 19.1 kN/m3 . Similarly imposed loads coming to the structure was determined according to IS:875 (Part II). Live load coming to the floor is taken as 2 kN/m2 and the live load coming to the roof is taken as 1.5 kN/m2 . Earthquake load computation is done as per IS:1893-2016 for Zone III, medium soil conditions with response reduction factor of 5 and importance factor of 1. All these loads are applied as different load cases in the structure with fixed base (FB) in SAP2000 for all the three plan configurations and load coming to the individual columns are found for design of the isolator.

5 Design of SFP Isolator Idealized force–displacement relationship of a SFP isolator is shown in Fig. 5. The various steps in the design [11] of an SFP isolator are shown below: 1. The isolator time period is a function of radius of curvature of concave surface. The natural time period is given by the expression:  Teff = 2π

R g

(1)

where R radius of curvature of sliding plate. 2. The isolator must be designed so as to withstand a lateral earthquake displacement which is given in accordance with the formula:   g/ 4 × π 2 CVD Teff = BD 

dmax

(2)

where dmax lateral earthquake displacements which act in the direction of each of the main horizontal axes of the structure Fig. 5 Idealized force–displacement relationship of a SFP isolator

Effectiveness of Base Isolation Using Single Friction Pendulum …

23

C VD seismic coefficient (as per UBC Table 16-R) BD numerical coefficient related to the effective damping of the isolation system at the design displacement (as per UBC Table 16-C). 3. The effective stiffness is the most important parameter of the isolator and it is a function of the vertical load W, coefficient of friction μ, radius of curvature of the sliding plates R and permissible displacement. It is calculated as follows, μW W + dmax R

K eff =

(3)

where K eff effective stiffness of the isolation system W weight on isolator. The coefficient of friction can be assumed between 0.02 and 0.10 depending on type of sliding surface and average bearing stress. Horizontal stiffness, K h is obtained as, K h = W/R

(4)

4. The energy dissipated for one cycle of sliding with amplitude d can be estimated as, E D = 4μW D

(5)

ED 4π D 2 K eff

(6)

5. The damping is estimated as β=

After the analysis of the structure with various loads and obtaining the load values on each columns, and the isolator properties are determined. Isolator properties for regular building, L-shaped building and C-shaped building are shown in Tables 2, 3 and 4, respectively. Table 2 Properties of SFP for Structure with regular plan SFP1

SFP2

SFP3

SFP4

SFP5

SFP6

W (kN/m)

862

855

849

576

573

374

μ

0.04

0.04

0.04

0.04

0.04

0.04

R (m)

2.2

2.2

2.2

2.2

2.2

2.2

K eff (kN/m)

576.98

572.51

568.32

385.51

383.54

250.34

K h (kN/m)

391.82

388.78

385.94

261.79

260.45

170

E D (kN m)

25.68

25.48

25.3

17.16

17.07

11.14

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R. Sharika and K. Venkataramana

Table 3 Properties of SFP for structure with L-shaped plan W (kN/m)

SFP1

SFP2

SFP3

SFP4

SFP5

SFP5

SFP7

966

960

854

643

635

420

413 0.04

μ

0.04

0.04

0.04

0.04

0.04

0.04

R (m)

2.2

2.2

2.2

2.2

2.2

2.2

2.2

K eff (kN/m)

646.59

642.58

571.63

430.39

425.04

281.13

276.44

K h (kN/m)

439.09

436.36

388.18

292.27

288.64

190.91

187.73

E D (kNm)

28.78

28.6

25.44

19.16

18.92

12.51

12.31

Table 4 Properties of SFP for structure with C-shaped plan W (kN/m)

SFP1

SFP2

SFP3

SFP4

SFP5

SFP6

736

557

553

369

367

363 0.04

μ

0.04

0.04

0.04

0.04

0.04

R (m)

2.2

2.2

2.2

2.2

2.2

2.2

K eff (kN/m)

492.64

372.83

370.15

246.99

245.65

242.97

K h (kN/m)

334.55

253.18

251.36

167.73

166.82

165

E D (kN m)

21.93

16.6

16.48

10.99

10.93

10.82

6 Analysis Modal analysis is carried out to compare the time periods of the structures with fixed and isolated bases. The dynamic structural response under loading in linear or nonlinear cases can be calculated using time history analysis. In SAP2000, the acceleration values in the function are assumed not to have units, instead, they are assumed to be normalized and the units are later expressed as a scale factor while defining the time history analysis case. Component 0 of the Chi-Chi Earthquake of September 25, 1999 at 23:52:00 UTC (Station: TCU129 Taichung, Taiwan) time history is applied in X-direction. The accelerogram data is shown in Fig. 6. Fig. 6 Chi-Chi earthquake accelerogram data

Effectiveness of Base Isolation Using Single Friction Pendulum …

25

7 Results and Discussion 7.1 Modal Analysis Installing a base isolator in a structure would increase its natural time period. This would help abate the effects of resonance to a large extent. Comparison of natural time periods obtained for fixed base buildings and buildings isolated with SFP for regular building, L-shaped building and C-shaped building is shown in Fig. 7 and the comparison of time periods for mode-10 is shown in Fig. 8, respectively. From Figs. 7 and 8, it is observed that there is a significant increase of time period in the case of SFP isolated building compared to fixed base building. The increase of natural time period is more compared to the increase in time period in mode-10. Thus, the effectiveness of SFP isolator reduces in the consecutive modes. And also it is observed that all categories of buildings, i.e. regular, L-shaped and C-shaped buildings show similar increase in time period. Thus, the effect of irregularity is not much coming into action in the case of time period. Fig. 7 Variation in natural time period—mode-1

Fig. 8 Variation in time period—mode-10

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R. Sharika and K. Venkataramana

7.2 Time History Analysis The accelerogram data for component 0 of the Chi-Chi Earthquake of September 25, 1999 at 23:52:00 UTC (Station: TCU129 Taichung, Taiwan) was obtained from COSMOS strong motion database. The accelerogram data was used in order to carry out the time history analysis of the structure. Figure 9 shows the comparison of reduction in base shear in the case of regular, L-shaped and C-shaped buildings on provision of base isolators. Detailed observations of base shear values for various plan configurations are given in Tables 5, 6 and 7. Fig. 9 Variation of base shear for fixed base and isolated base buildings

Table 5 Comparison of base shear for regular building

Base shear (kN) FB

SFP

% Reduction

Maximum

1301.58

468.36

64.02

Minimum

1248.04

502.16

59.76

FB

SFP

% Reduction

Maximum

602.04

205.82

40.81

Minimum

614.25

235.43

39.90

FB

SFP

% Reduction

Maximum

373.19

225.82

39.49

Minimum

382.39

235.43

38.43

Table 6 Comparison of base shear for L-shaped building

Base shear (kN)

Table 7 Comparison of base shear for C-shaped building

Base shear (kN)

Effectiveness of Base Isolation Using Single Friction Pendulum …

27

Analyzing various plan configurations, the percentage reduction in base shear by the introduction of SFP isolator is found to be maximum for regular building. And the percentage reduction of base shear is found to be reducing as more and more irregularity is introduced to the structure. A comparison of storey acceleration, for fixed base and isolated base has been made for structures subjected to the accelerogram of Chi-Chi earthquake data. Reduction in acceleration results in decreased inertia force and hence the extent of damage decreases to a large extent. The variation of top storey acceleration for fixed base and isolated base buildings are shown in Fig. 10. The top storey acceleration is found to be reducing for all the plan configurations, but the reduction is more in the case of regular building compared to the irregular buildings. As the irregularity appeared in the plan increases, the acceleration reduction, i.e. the effectiveness of SFP isolator reduces. Figure 11 depicts the acceleration in various cases. Figure 12 shows a comparison of storey drift of structures with fixed base and that with an isolated base, for 4-storey structures with regular plan, L-shaped plan and C-shaped plan with fixed base and with SFP, respectively. The relative storey drift has been observed to be less in the case of SFP isolated buildings. But there is no observable trend in the reduction of effectiveness of SFP due to irregularity in terms of relative storey drift. But from the base shear and storey accelerations, it is clearly observed that the effectiveness of SFP isolation is reduced by the introduction of asymmetry in plan configuration.

8 Conclusions The study includes a detailed review of the different base isolation techniques available and it reveals that a single friction pendulum isolator has an upper hand over other isolator systems due to its restoration ability owing to its curvature and geometry. Fig. 10 Variation in top storey acceleration in fixed base and isolated base buildings

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Fig. 11 Variation in top storey acceleration in fixed base and isolated base buildings for regular, L-shaped and C-shaped plan configurations

A regular four storied structure, an L-shaped four storey structure and a C-shaped four storey structure were modelled with and without single friction pendulum isolator. After the modelling and time history analysis of structures, the following conclusions are made, • Base isolation using single friction pendulum reduces the base shear, storey acceleration and relative drift between storeys to good extent. The study shows that the relative displacement at the floor is approximately zero for isolated buildings which in turn reduces the inertia forces to a large extent.

Effectiveness of Base Isolation Using Single Friction Pendulum …

29

Fig. 12 Variation in relative storey displacement in fixed base and isolated base buildings

• Base shear reduction in regular building is maximum and for C-shaped building, it is minimum. That is base shear reduction is affected by the irregularity of the structure. • Base isolation increases the time period of the structure considerably, thereby reducing the chances of resonance. This time period increment is more in the case of natural time period of the structure and this increase decreases over the consecutive modes. • By considering the difference in reduction of base shear, storey acceleration, etc., in regular building and irregular buildings, it can be concluded that the effectiveness of isolation reduces as irregularity present in the structure is increased. The present study covered only irregularity in plan of the structure. The effect of other irregularities also can be studied and the overall effectiveness of isolators can be monitored.

References 1. Fan FG, Ahmadi G, Tadjbakhsh IG (1988) Multi-story base-isolated buildings under a harmonic ground motion-part I: a comparison of performances of various systems. Nucl Eng Des 123:1– 16 2. Su L, Ahmadi G, Tadjbaksh IG (1988) Performance of earthquake isolation system. J Eng Mech 115(9), Paper No. 23857 3. Su L, Tadjbakhsh IG, Papageorgiou A, Ahmadi G (1990) Performance of earthquake isolation system. J Eng Mech 116(2), Paper No. 24383 4. Liauw TC, TianQL, Cheung YK (1988) Structure on sliding base subject to horizontal and vertical motions. J Struct Eng 114(9):2119–2129 5. Mokha A, Constantinou MC (1991) Experimental study of friction pendulum isolation system. J Struct Eng 117(4), Paper No. 25738 6. Scheller J, Constantinou MC (1999) Response history analysis of structures with seismic isolation and energy dissipation systems: verification examples for program SAP2000. Technical Report MCEER-99-0002

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7. Naveen K, Prabhakara H, Eramma H (2015) Base isolation of mass irregular RC multi-storey building. Int Res J Eng Technol 902–906 8. Parma V, Hiremath GS (2015) Effect of base isolation in multistoried Rc irregular building using time history analysis. Int J Res Eng Technol 2319–2322 9. Nassani DE, Abdulmajeed MW (2015) Seismic base isolation in reinforced concrete structures. Int J Res Stud Sci Eng Technol 2:1–13 10. Shah VA, Bakhaswala HC, Chandiwala AK, Tank YR (2017) Comparative study of base isolation in multistoried R.C irregular building. Int J Adv Eng Res Dev 4(11):354–362 11. Andrade L, Tuxworth L (2009) Seismic protection of structures with modern base isolation technologies. Concrete Solutions, Paper 7a-3

Review Paper on Behavior of Cold-Formed Steel Sections Under Axial Compression Asim Bahadur , Kiran Shinde , and Vidya Patil

Abstract Steel is used in construction industry due to its hardness and tensile strength. Cold-formed steel is type of steel which is manufactured at lower temperature. Cold-formed steel becomes more popular in twentieth century in civil engineering field as it possesses high strength to weight ratio and post-buckling strength. Research in cold-formed steel has increased considerably in past few years. Researchers have been working to develop direct strength method to replace conventional effective width method which is more tedious and less accurate. In this paper, we have studied various methods adopted for estimation axial load carrying capacity of cold-formed steel channel, angle and Z sections by various researchers. Keywords Cold-formed steel · Channel section · Angle section · Z section · Effective width method · Direct strength method

1 Introduction Steel is used in the construction and other applications due to its hardness and tensile strength [1]. Two types of steel members are used in civil engineering field as common practice namely hot-rolled and cold-formed steel. Hot-rolled steel members are produced at high temperatures, whereas cold-formed steel members are produced at lower temperatures [2]. Hot-rolled steel members are manufactured at a temperature higher than 1700 °F, which is above the recrystallization temperature of steel, and hence, the sections can be molded into any desired shape of any size. Coldformed steel sections members are formed by folding or rolling at room temperature without application of heat [3]. Cold-formed material became popular in early twentieth century around in 1920s, and its usage grew in last two decades as they are suitable for lighter load bearing application. They are used in construction industry as purlins, roof sheets and floor A. Bahadur (B) · K. Shinde · V. Patil Department of Civil Engineering, Annasaheb Dange College of Engineering & Technology, Ashta, India e-mail: [email protected] © Springer Nature Singapore Pte Ltd. 2021 M. C. Narasimhan et al. (eds.), Trends in Civil Engineering and Challenges for Sustainability, Lecture Notes in Civil Engineering 99, https://doi.org/10.1007/978-981-15-6828-2_3

31

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A. Bahadur et al.

decks. The cold-formed members can be manufactured by using two methods which are press-braking or cold roll forming [4]. As the manufacturing is done at the room temperature, the cold-formed steel sections are commonly thin walled members having thickness 0.4–6.5 mm [5]. The less thickness results into the higher slenderness ratio. Due to this higher slenderness ratio, under axial compressive loading, the failure occurs due to the local, distortional, flexural and distortional–flexural type of buckling or yielding [5]. As the sections may fail by different types of buckling, estimating the load carrying capacity of cold-formed steel sections is very complicated [6]. But the post-buckling strength is an advantage which encourages the use of cold-formed steel. Hence, all these parameters should be considered before adopting a method to calculate the strength of cold-formed steel sections under axial compressive loading [7]. Research into cold-formed steel structures has increased considerably in past few decades. Initially, only the effective width method (EWM) was used for analyzing cold-formed steel members. But later on, the researchers shifted their area of interest from effective width method to direct strength method. The recent editions of the North American Specification and the Australian/New Zealand Standard added the direct strength method of design with the effective width method. From there methods based on the finite strip method (FSM), the constrained finite strip method (cFSM) and generalized beam theory (GBT) were also presented by some authors [3]. A review of the previous study of the behavior of cold-formed steel under axial compressive loading has been included in this review.

2 Methods of Analysis 2.1 Effective Width Method (EWM) Effective width method has been used for the estimation of compressive strength of the cold-formed steel members over many decades. Effective width method presents a semi-empirical equation which takes into account the effect of local buckling [8]. Von Karman et al. introduced the effective width method, and later, George Winter modified it [9]. In the North American Specification, for the design of cold-formed steel members, it was the main design approach for a long time [5]. Effective width method considers the effect of the interaction between local bucking and the postbuckling strength [6]. In EWM, instead of considering non-uniform distribution of stress across the width of the element, it is assumed that the total load is carried by an imaginary width, this is called as the “Effective Width.” This effective width is assumed to be subjected to a uniformly distributed stress which is equal to the edge stress [10]. George Winter proposed a formula to determine the post-buckling strength of a stiffened cold-formed element that is known as the “Winter’s equation” [6].

Review Paper on Behavior of Cold-Formed Steel Sections …

33

In this method, an over stability strength is first used to account for overall buckling followed by the reduction of gross section area to the effective area using effective width formula which accounts interaction various modes of bucking. Some part of distortional buckling is also considered in EWM [9]. Xingyou et al. [9] used energy method and large deflection theory to propose modifications in Chinese code to account overall distortional buckling in effective width method. Bock and Real [11] also presented EWM equations for studying cold-formed steel hollow rectangular and square section.

2.2 Direct Strength Method (DSM) The calculation of the effective width of individual elements becomes more difficult and inaccurate when the profile and cross section of the member become complex with extra lips and stiffeners. To solve this problem, the direct strength method (DSM) was developed in 1988 [6]. Schafer was first person who presented the approach to use the DSM for cold-formed steel member design [12]. This approach of coldformed steel design is in continuous development, and many researchers are working continuously. In direct strength method, the member elastic stability is determined using all of the elastic instabilities. For any section, the instability may occur due to local, distortional or global buckling. Also, the moment or load that causes the section to yield is determined, and then, the strength is directly determined [13] as mentioned in (1) below.   i.e., Mn = f Mcrl , Mcrd , Mcre , M y

(1)

There are so many elastic buckling modes in which a cold-formed steel member can be deformed, and these modes are crucial when we analyze cold-formed steel members. The phenomenon in which the energy associated with out-of-plane deformation response to an in-plane load and the energy for in-plane response to the same in-plane load are equal is called as elastic buckling. And the load for which the equilibrium of the member is neutral between buckled and straight states is called as elastic buckling load. Silvestre et al. [10] found that NLD DSM approach holds fairly good in study interaction of local and distortional buckling in lipped channel cold-formed steel members with simply supported support conditions.

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3 Literature 3.1 Channel Sections Yokar and Alandkar [7] used effective width method (EWM) to determine the load carrying capacity of cold-formed steel channel sections under compression subjected to concentrated loading for different lengths. Methodology available in both Indian standard (IS: 801-1975) and British Standard (BS: 5950-5:1998) were adopted to determine the load carrying capacity of sections. A channel section of 250 × 80 × 25 mm with a lip of 5 mm was used by the authors in this study. Figure 1 shows the geometry of the section. In IS methodology, analysis is done by considering corner effect, whereas in British Standard, mid line dimensions are used. Their findings are listed in Table 1. Table 1 shows comparison of load carrying capacity values through two different methods. From Table 1, it was observed that methodology adopted in Indian Standard (IS: 801:1975) is more reliable than calculations by British Standard (BS:59505:1998) as the British standard values are upper bound in comparison with Indian Standard.

Fig. 1 Lipped channel section

Table 1 Loads obtained from Indian and British code Section

250 × 80 × 25 × 5

Length (m)

Load carrying capacity (kN) British Standard BS: 5950-5:1998

Indian Standard IS: 801-1975

1

211.22

216.08

3

115.07

123.86

5

41.46

44.94

10

10.37

11.23

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35

Keerthana and Jothibaskar [14] studied behavior of built-up cold-formed steel sections using two channel sections placed back to back with and without lip using direct strength method (DSM) based on provisions provided in American Iron and Steel Institution (AISI-S100:2007) and compared it with models generated by finite strip method. The authors developed finite strip method by constrained and unconstrained finite strip method (CUFSM) software and took the ultimate load carrying capacity from GBTUL software. Figure 2 shows the failure modes of channel sections with and without lip in experiments performed and models generated in GBTUL by the authors. Table 2 shows the comparison of ultimate load of sections estimated from software (GBTUL) and experiments performed by Keerthana and Jothibaskar [14]. Along with this, a ratio of ultimate load calculated by direct strength method (DSM) to the ultimate load estimated by experiment performed is mentioned. From Table 2, it is clear that the strength almost doubles if lip is provided. It can be also observed that ultimate load predicted using direct strength method (DSM) equations in AISI-S: 2007 are having average difference of 8–26% with experimental results.

Fig. 2 Modes of failure

Table 2 Comparison of experiment, DSM and GBTUL Section (mm)

Ultimate load (kN)

120 × 50 × 1.6

With lip (1.6 mm)

140 × 60 × 1.6

With lip (1.6 mm)

Without lip Without lip

PDSM /PEXP

PEXP

PGBTUL

PDSM

152.2

149.58

112.702

89.70 157.6 84.02

86.11

82.586

0.740 0.920

137.106

136.79

0.868

73.66

67.69

0.805

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A. Bahadur et al.

Fig. 3 Boundary conditions

Ananthi et al. [15] studied cold-formed steel lipped channel sections of three different widths and four different slenderness ratio under axial compression. And the obtained results were compared with North American Standards by the authors. Authors of this papers used ABAQUS 6.14 for simulation of the section with boundary condition as shown in Fig. 3. Authors of this paper proposed a modified equation for column strength which is represented by (2), ∗ ∗ = 1.31PNAS PFEA

(2)

Ananthi and Samuel Knight [16] did an extensive study on cold-formed steel channel sections using finite element method in ABAQUS software and compared it with the theoretical results obtained by the Indian Standard (IS: 801:1975), British Standard (BS: 5950-Part 5) and NAS Manual of American Iron and Steel Institute (AISI:2007) to study the effect of lip, thickness, size of section and yield strength of the material on the modes of failure. Numerical simulation was done in ABAQUS using S4R5 element with pin ended boundary conditions. From the results obtained by Ananthi and Samuel Knight [16], it was also found that results obtained from Indian Standard are closer to the numerical solutions obtained from ABAQUS than the British code which validate the work done by Yokar and Alandkar [7]. Also, it was also seen that the results of all the codes hold good results up to the slenderness ratio of 120. After the slenderness ratio of 120, the error becomes more significant. In some cases, it went on to a higher value of 80% in NAS method. Anarbasu et al. [17] studied built-up battened columns numerically and theoretically under axial compressive loading. Software package ABAQUS was used for numerical modeling, and the theoretical axial compressive strength was calculated by using direct strength method (DSM) approach provided in American Iron and Steel Institution (AISI S100-2007). Figure 4 shows the experimental versus numerical models generated in ABAQUS. Authors calibrated all the numerical simulations using the experimental work given performed by El Aghoury et al. for validation work.

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37

Fig. 4 Experimental versus FEM models

Authors of [17] used two different approaches of direct strength method (DSM) for this research work. In the first approach, i.e., DSM-1, finite strip analysis software CUFSM was used to estimate ultimate strength. The ultimate strength of the built-up section was considered equal to the sum of the ultimate strength of two lipped single channel sections where the effect of batten plates (number and depth of plates) is neglected. Whereas in second approach, i.e., DSM-2, the finite element software ABAQUS was used to obtain the elastic buckling solutions. These values of elastic buckling solutions were substituted in the DSM equations, and the critical Euler’s buckling stress was calculated by using a modified slenderness ratio which is provided in AISI S100-2007. Equation (3) below represents the modified slenderness ratio. 

KL r



 = m

KL r

2 + o

 2 a ri

(3)

From the results obtained by the authors of this literature [17], it was found that the DSM-1 approach was found conservative and the modified slenderness ratio in DSM-2 approach predicted the strength of the built-up columns un-conservatively. Anarbasu et al. [17] found that load carrying capacity increases with increasing slenderness ratio indicating the possibility of presence of post-buckling strength and present direct strength method (DSM) method is conservative in estimating the ultimate load of the cold-formed steel sections. Hence, authors made indications about need of further calibration required in direct strength method (DSM) for getting reliable results.

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Table 3 Approximate error in computation Code

Method

Error (%)

IS: 801-1976

EWM

40

BS 5950

EWM

53

NAS 2007

DSM

43

Table 3 shows the maximum error or deviation found between the experimental load obtained and calculated using various codas across the world in the literature [16].

3.2 Angle Sections Vani et al. [18] made studies to investigate elastic buckling and the nonlinear behavior of pin ended cold-formed steel equal angles using ABAQUS. The specimens were studied for different width to thickness (b/t) ratio and different lengths, but the thickness was kept constant. And they compared the results with the results obtained from effective width method (EWM) in IS code and direct strength method (DSM) in AISI 2007. Table 4 shows the comparison of results obtained from all methods adopted by the authors of literature [18]. From the results in Table 4, it can be seen that load estimated by DSM is higher than that of EWM, whereas the load estimated by EWM is on lower side. Also, the load estimated by DSM is more precise with mean error of 12% than EWM which has error of 41%. It can also see that with increase in b/t ratio, the error increases up to 69% in EWM and 27% in DSM. Chodraui et al. [19] examined the cold-formed steel equal angle section. They used effective width method (EWM), direct strength method (DSM), experimental, and finite element method (FEM) for studying the strength and the stability of the members. Authors found that two main failure modes involve the local plate/global torsional and flexural type of buckling. Table 4 Load estimated from IS:801, AISI 2007 and FEM Section (mm)

60 × 60 × 2

Length (mm)

Error (%)

EWM IS:801-1976

DSM AISI 2007

FEM

EWM

DSM

13.76

16.38

16.69

21

2

90 × 90 × 2

8.93

11.32

12.11

36

7

120 × 120 × 2

6.69

8.84

11.24

69

27

41

12

Mean

600

Load (kN)

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39

Mmrsharif et al. [20] studied the behavior of cold-formed unequal angle sections for compressive loading and compared the estimated loads with IS provisions. They found IS code predicting the strengths conservatively. Also, due to provision of lips as the stiffeners, the sections fail due to distortional buckling. Popovic et al. [21] also compared the results of Australian and New Zealander code (AS/NZS4600) and American code (ALSI 2007) with experimental results for cold-formed steel angle sections. They found that experimental test results to be 108 and 186% higher than that of above codes. Ananthi [22] examined the compressive strength of cold-formed steel built-up double angles placed as a box section with pin ended support condition. He chose four different cross sections with two different thicknesses. S4R5 thin shell element in ABAQUS was used to numerically simulate the built-up double angle columns. Theoretical load was calculated by Australian and New Zealander code (AS/NZS 2005) and North American Standards (NAS 2007). Ananthi performed tension coupon test to find out all the material properties. Figure 5 shows the comparison of failure modes of section found experimentally and using numerically simulated using ABAQUS by Ananthi [22]. From results, local failure mode was found for slenderness ratio less than 20, whereas it became combination of local and flexural for slenderness ratio higher than 30. Also, author stated that the DSM equations used for this work proved to be conservative in estimation of load carrying capacity of lipped angle section. From above discussion, the approximate error in different codes found is enlisted in Table 5. Table 5 shows the approximate error in various design methods across the world. With this, it can be concluded that the AISI 2007 which follows DSM method is more precise in prediction of ultimate load carrying capacity of cold-formed angle sections.

Fig. 5 Experimental versus FEM failure modes

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A. Bahadur et al.

Table 5 Approximate error in computation Code

Method

Error (%)

IS: 801-1976

EWM

41

AS/NZS4600

EWM

86

AISI 2007

DSM

11

Table 6 Approximate error in computation Code

Method

Error (%)

NSCP

EWM

52

AISI 1986

EWM

20

3.2.1

Z Sections

Polyzois and Sudharmapal [23] performed compression tests on cold-formed steel Z sections with lip angle ranging from 0° to 80° and compared it with the theoretical results obtained using American Iron and Steel Institute (AISI 1986). In conclusion, authors of this paper stated that the results obtained from American Iron and Steel Institute (AISI 1986) are quite appropriate for lipped Z section but are conservative for unlipped sections. Matthew et al. [24] performed experiments in 180 specimens of six different thicknesses and six different lengths but of same cross section of Z section to study its behavior under axial compressive loading. And the results were compared with computational results obtained using National Structural Code of the Philippines (NSCP). They found that majority of sections failed due to torsional–flexural type of buckling. And Philippines code was found non-conservative with a suggested modification factor of 0.52. Table 6 shows average deviation in two different codes in calculation of load carrying capacity of a cold-formed steel Z section. From above results, it can be clearly seen that the AISI 1986 is clearly more reliable than the NSCP.

3.3 Other Shapes Young et al. [25, 26] performed series of test on cold-formed hollow rectangular and oval sections to calculate their buckling strength and compared them with the same estimated using American, Euro and Australian/New Zealander codes. In results, they found AS/NZ code more reliable for both hollow rectangular and hollow oval sections.

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41

Deepla and Venkat [27] carried out comparative study on angle and channel section by keeping the width to thickness (b/t) ratio a constant parameter and by varying length of the sections. Authors found channel sections to be more efficient than the angle section in this study.

4 Conclusion Results from various literatures have been studied during this review. Most of the work was done using ABQUS software which held fairly good in numerical simulation of the sections. From the literature, it was seen that DSM equations presented by Schafer which are adopted in AISI and AS/NZ as alternative to conventional effective width method are more precise than the EWM in analyzing the cold-formed steel sections. But there is still need of more modifications in present DSM equations to apply them to complex shapes and profiles. Comparative study based on w/t ratio shows that the channel sections perform better in axial compressive loading.

5 Future Scope Authors of this paper are working toward studying the behavior of cold-formed steel channel, angle and Z sections of same cross-sectional area under axial compressive loading as a comparative study so as to suggest best suitable or most economical section among them to carry axial compressive load. ANSYS is being used for numerical simulation of sections in this research work. Experiments will be performed for the same sections for validation and calibration of the numerical solution. Though many researchers have gone with ABAQUS software package, but the authors of this paper are working with ANSYS because of its user friendliness. It will also be the topic of discussion that how the ANSYS interprets the results.

References 1. Jothi Baskar K, Aravindh R, Ashik Elahi A, Mohanraj B, Prakash A (2016) Experimental study on behaviour of cold-formed steel using C channel section under axial compression. IJIRST Int J Innov Res Sci Technol 2:194–197 2. Sharma A, Selvan SS, Babu SS, Elango D (2016) Experimental study on the flexural-torsional behavior of cold-formed steel channel section connected back to back. Indian J Sci Technol 9:1–8 3. Hancock GJ (2016) Cold-formed steel structures: research review 2013–2014. Adv Struct Eng 1–16

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4. Agastheesh MG, Selvan SS (2016) Behaviour of cold-formed steel starred section subjected to axial and eccentric load condition. Indian J Sci Technol 9:1–7 5. Kalavagunta S, Naganathan S, Mustapha KNB (2013) Experimental study of axially compressed cold-formed steel channel columns. Indian J Sci Technol 6:4249–4254 6. Kalavagunta S, Naganathan S, Mustapha KNB (2013) Theoretical study of axially compressed cold-formed steel sections. Int J Adv Stud Comput Sci Eng 2:67–74 7. Yokar NN, Alandkar PM (2014) Comparison of compression capacity of cold-formed steel channel sections under concentrated loading by analytical methods. J Civ Eng Environ Technol 1:28–32 8. Batista EM (2009) Local–global buckling interaction procedures for the design of cold-formed columns: effective width and direct method integrated approach. Thin-Walled Struct 47:1218– 1231 9. Xingyou Y, Yanli G, Yuanqi L (2016) Effective width method for distortional buckling design of cold-formed lipped channel sections. Thin-Walled Struct 109:334–351 10. Silvestre N, Camotim D, Dinis PB (2009) Direct strength prediction of lipped channel columns experiencing local-plate/distortional interaction. Adv Steel Constr 5:49–71 11. Bock M, Real E (2015) Effective width equations accounting for element interaction for coldformed stainless steel square and rectangular hollow sections. Structures 2 12. Kumar MVA, Kalyanaraman V (2010) Evaluation of direct strength method for CFS compression members without stiffeners. J Struct Eng 136:879–885 13. Schafer BW, Pekoz T (1998) Direct strength prediction of cold-formed steel members using numerical elastic buckling solutions. In: 14th International specialty conference on cold-formed steel structures, St. Louis, Missouri 14. Keerthana SP, Jothibaskar K (2016) Experimental study on behaviour of cold-formed steel using built-up section under axial compression. IRACST Eng Sci Technol Int J (ESTIJ) 6:74–77 15. Ananthi GBG, Palani GS, Iyer NR (2015) Numerical and theoretical studies on cold-formed steel unlipped channels subjected to axial compression. Latin Am J Solids Struct 12:1–17 16. Ananthi GBG, Samuel Knight GM (2013) Behaviour of cold-formed steel channel sections under axial compression. In: The 4th international conference of EACEF (European Asian civil engineering forum), National University of Singapore, Singapore, pp 55–60 17. Anbarasu M, Bharath Kumar P, Sukumar S (2014) Study on the capacity of cold-formed steel built-up battened columns under axial compression. Latin Am J Solids Struct 11:2271–2283 18. Vani G, Jayabalan P, Joseph J (2013) Numerical analysis of cold-formed steel plain angle compression members. Int J Emerg Technol Adv Eng 3:22–29 19. Chodraui GMB, Shifferaw Y, Malite M, Schafer BW (2006) Cold-formed steel angles under axial compression. In: Eighteenth international specialty conference on cold-formed steel structures, Orlando, Florida, USA, pp 285–300 20. Mmrsharif G, Janarthanan S, Vani G (2016) Experimental investigation of buckling behavior of lipped unequal angle cold-formed steel section subjected to compression. Int J Eng Res Technol (IJERT) 4:1–4 21. Popovic D, Rasmussen KJR, Hancock GJ (2000) Compression tests on cold-formed angles loaded parallel with a leg. In: Fifteenth international specialty conference on cold-formed steel structures, St. Louis, Missouri, USA, pp 255–279 22. Ananthi GBG (2018) A study on cold-formed steel compound angle section subjected to axial compression. KSCE J Civ Eng 22:1803–1815 23. Polyzois D, Sudharmapal A (1988) Cold-formed steel Z-sections under axial load. In: 9th International specialty conference on cold-formed steel structures, St. Louis, Missouri, USA, pp 115–127 24. Matthew J, De Jesus L, Lejano BA (2018) An investigation on the strength of axially loaded cold-formed steel Z-sections. Int J GEOMATE 14:30–36 25. Young BMA, Zhu J (2011) Cold-formed-steel oval hollow sections under axial compression. J Struct Eng 137:719–727

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26. Young BMA, Liu Y (2003) Experimental investigation of cold-formed stainless steel columns. J Struct Eng 129:169–176 27. Deepla N, Venkat R (2018) Comparative study on cold-formed light gauge steel angle sections and channel sections of compression members. Res Rev J Appl Sci Innov 2:7–14

Analysis of Anchorage Zone Stresses in Post-tensioned Concrete Girders C. D. Dipindas, M. H. Prashanth, and P. Lakshmy

Abstract Application of pre-stressed concrete for the construction of civil engineering structures especially bridges has increased tremendously. In the pre-stressed post-tensioned concrete structures, anchorage zone is the critical area of concrete ahead of the anchorage device. During application and diffusion of the pre-stressing force in a post-tensioned girder, tensile bursting stresses are developed at some distance ahead of the anchorage device in a region known as the general zone. These stresses often lead to serviceability problems and congestion of reinforcement at the anchorage zone. In this paper, a rectangular end block of 600 × 600 mm, with a bearing plate size of 214 × 214 mm, subjected to a concrete pre-stressing force of 2204 kN was analysed using the methods like elastic method, deep beam analogy, strut-and-tie model approach, finite element analysis and also using the codal provisions specified in IRC: 18 and British code BS: 8110. From the analysis of 2D finite analysis, it was observed that the variation of bursting stress in the end block is parabolic in nature. It was observed that with increase in eccentricity of bearing plate, there was a decrease in bursting tensile stress, whereas the value of spalling tensile stresses increases drastically. However, with increase in the size of the bearing plate, both the spalling and bursting stresses decrease considerably. It was also found that the grade of concrete has negligible effect on the distribution which is of bursting tensile stress. The finite element analysis of anchorage zone with multiple anchors indicates that spalling stresses are more critical than the bursting stresses for the design of anchorage zone. Keywords Pre-stressed concrete · Anchorage zone · Bursting tensile stress · Spalling tensile stress

C. D. Dipindas · M. H. Prashanth (B) Department of Civil Engineering, National Institute of Technology Karnataka, Surathkal, Surathkal, Mangalore, Karnataka 575025, India e-mail: [email protected] P. Lakshmy Bridges and Structures Division, Central Road Research Institute, New Delhi, India © Springer Nature Singapore Pte Ltd. 2021 M. C. Narasimhan et al. (eds.), Trends in Civil Engineering and Challenges for Sustainability, Lecture Notes in Civil Engineering 99, https://doi.org/10.1007/978-981-15-6828-2_4

45

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C. D. Dipindas et al.

1 Introduction Pre-stressed concrete is a structural concrete in which internal stresses of suitable magnitude and distribution are introduced so that the stresses resulting from the external loads are counteracted to a desired degree. This is accomplished by combining the best properties of the two quality materials: high compressive strength of concrete and high tensile strength of steel strands. Though the pre-stressed concrete has many advantages, it also presents some challenges. The anchorage zone, or the region where the pre-stressing force is transferred from the tendon to the concrete, is susceptible to cracks that are formed due to the tensile stresses caused by the prestressing force. When the stress exceeds modulus of rupture of the concrete, the end block cracks longitudinally leading to serviceability problems, unless appropriate vertical reinforcement is provided. Post-tensioning allows for reduced cross-sectional area in bridges. Reduced crosssectional area indicates that only limited space is available for the placement of anchorage devices and confinement of shear and general zone reinforcement. The anchorage zone becomes highly congested, resulting in difficulty in the placement of concrete leading to adverse affect in the bond between concrete and reinforcing steel, which is likely to cause failure of anchorage zone. In addition, when structures are exposed to extreme environments, cracking of concrete and corrosion of reinforcing steel occurs. Thus, there is a need for a comprehensive study of the three-dimensional nature of anchorage zone stresses. Pre-stressing tendons are anchored at their ends to transfer the compressive force to the concrete. The anchorage consists of a bonded length of the tendon, in direct contact with the concrete. A bearing plate is used, which bears onto the concrete over a relatively small cross-sectional area. The tendon is connected to the plate either through wedges or button heads which compresses and redistributes the stresses that occur behind the bearing plate so that the compression trajectories spread out to form uniform stress patterns at some distance into the concrete. This disturbed region is known as the anchorage zone. It must be ensured that the anchorage zone must not crack at the limit state of serviceability and the zone must not fail at the limit state of collapse. Various researchers have attempted to study the anchorage zone stresses in prestressed concrete structures. The experimental investigation by Tsavalas [1] indicated that the failure of the end block is caused by bursting tension and some reinforcement is necessary to counteract the transverse tension. From studies conducted by Marshal and Mattok [2], it was concluded that to ensure satisfactory control of the cracking, a relatively small amount of vertical stirrups was required, and tendon placement has a major influence on the distribution of stress at transfer. They also found that the magnitude of the stirrup force is a function of the strand transfer length, beam depth and pre-stressing force for a given cross section. Gergely and Sozen [3] analysed the effect of the transverse reinforcement in the anchorage zone behaviour based on the equilibrium conditions of the cracked anchorage zone. They experimentally investigated influence of various factors such as the position of crack, geometrical

Analysis of Anchorage Zone Stresses in Post-tensioned …

47

shapes of the end block, amount of reinforcement and size of the loading plate. Sundra Raja Iyengar and Prabhakara [4] conducted various experimental investigations to examine the effect of the ratio of the loaded depth to depth of the end block on the position of zero and maximum transverse tensile stresses, the magnitude of maximum tensile stresses and bursting force and the existence of spalling tension near the loaded space. Zhongguo et al. [5] have presented a method for optimization of post-tensioning anchorage in pre-stressed concrete I-beams by conducting analytical and experimental studies and improved the anchorage zone detailing. Sundra Raja Iyengar [6] presented a theoretical solution for the 2D elasticity problem of the anchorage zone stresses in post-tensioned concrete beams under all the four types of loading cases, i.e. normal and tangential, symmetrical and antisymmetrical. Yettram and Robbin [7] were the pioneers in presenting the detailed studies on stresses in anchorage zone in post-tensioned members. They used finite element method to analyse the stress distribution studies of the bursting stress in concentrically loaded beam with uniform rectangular section. They also did studies on the stress distributions for multiple and eccentric anchorage on both rectangular and I-section members [8]. The effect of the flange in I-section was found to reduce the spalling stresses. Sarles and Itani [9] used finite element method to study the effect of end blocks on anchorage zone. It was found that the maximum transverse tensile stresses increased with increase in transition length or with eccentricity. Hengprathanee [10] had conducted linear and nonlinear FE analyses of anchorage zones in post-tensioned concrete structures. A new approach for the design of a non-rectangular anchorage zone was proposed. In this study, the 3D nature of the stresses in anchorage zone of a pre-stressed concrete girder is carried out with the help of theoretical studies. The scope of this work includes detailed study of various methods generally adopted for the analysis of the anchorage zone stresses in the post-tensioned concrete girders and investigates the effect of parameters like size, eccentricity of bearing plate and grade of concrete on the anchorage zone stresses. It also includes study of stresses in anchorage zone with multiple anchorages using 2D and 3D finite element analyses.

2 Methods for Analysis and Design of Anchorage There are different methods of analysis of post-tensioned anchorage zones such as elastic analysis, deep beam analogy, strut-and-tie method and finite element analysis available for the analysis of anchorage zone. The main objective of the stress analysis of the anchorage zone is to obtain the transverse tensile stress distribution from which the total transverse bursting tension could be computed for the design. Elastic analysis is an excellent tool for predicting where and when the first significant cracking of the concrete is likely to occur. However, after the cracking, there will be a significant redistribution of the internal stresses and this cannot be predicted by traditional elastic analysis. On the basis of elastic analysis, a simple expression recommended by Leonhardt [11] could be used to conservatively estimate the total

48

C. D. Dipindas et al.

bursting tensile force F bst , obtained by integrating the bursting stresses as in (1). Fbst

  ypo = 0.25 Pk 1 − yo

(1)

where Pk = maximum pre-stressing force due to post-tensioning operation, ypo = depth of bearing plate and yo = depth of the member. In deep beam analogy, a simpler approach for estimating the tensile forces considers the end zone as a deep beam subjected to the bearing stresses on the free end and subjected to the statically equivalent, linearly distributed stresses on the other end. The depth of the equivalent deep beam is taken as the length of the distributed zone. This approach for the design of the end block was proposed by Magnel [12] and further developed by Gergely and Sozen [3]. In Magnel’s method, the end bock is considered as a deep beam subjected to concentrated load due to anchorage on one side and subjected to normal (direct stress) and tangential (shear stress) distributed loads from the other side. The stress distribution across the section can be approximated by the following equation:  fv = K 1

M bh 2

 

τ = K3 fh =

 + K2 V bh

H bh

 (2)



  e2 P 1 + 12 2 bh h

(3)

(4)

where K 1 , K 2 and K 3 are constants depending on distances away from the end face of the beam, M = bending moment, H = direct force (vertical), V = shear force (horizontal), f v = vertical stress, f h = direct stress, τ = shear stress, p = pre-stressing force, b = breadth of end block and h = depth of end block. The principal stresses acting at the point are computed by the Eqs. (5) and (6). The bursting tension is computed using the principal tensile stress distribution about the required axis.   1 fv + fh ± f max or f min = ( f h − f v )2 + 4τ 2 2 2   2τ tan 2θ = fv − fh 

(5) (6)

Guyon [13] developed design tables for the computation of bursting tension which are based on the theoretical studies regarding the distribution of stresses in the end blocks subject to concentrated loads. When the forces are evenly distributed, i.e. forces are arranged such that the resultant of the stress distribution at a distance equal to the depth of the end block coincides with the line of action of the forces; the

Analysis of Anchorage Zone Stresses in Post-tensioned …

49

bursting tension is expressed as   0.58  Fbst = 0.3 Pk 1 − ypo /yo

(7)

where Pk = anchorage force, ypo /yo = distribution ratio, 2ypo = depth of the bearing plate and 2yo = depth of the equivalent prism. When it is not possible to arrange the end forces evenly, transverse tensile stresses can be investigated along successive resultants, such as (a) resultant of all forces, (b) resultant of smaller groups of forces and (c) lines of action of individual forces. The line of action of the resultant force is taken as the axis of an equivalent prism of length and depth equal to twice the distance of axis from the free edge or the adjoining equivalent prism. Experimental investigations on concrete prismatic specimens conducted by Zielinski and Rowe’s [14] using the technique of surface-strain measurements lead to development of relations to compute the maximum transverse tensile stress and bursting tension. The transverse stress is found to be maximum at a distance equal to 0.5y0. The recommended equations are given as: Tensile stress  

ypo (8) f v(max) = f c 0.98 − 0.825 yo valid for ratio of (ypo /yo ) = 0.3 to 0.7. Bursting tension, Fbst

 

ypo = Pk 0.48 − 0.4 yo

(9)

If allowance is made for tension to be taken by concrete, the corrected value of the bursting tension is given by  Fbst (corrected) = Fbst 1.0 −

ft f v(max)



(10)

where f t = permissible tensile strength of concrete, 2y0 = sides of the surrounding prism, 2ypo = side of loaded or punching area, ypo /yo = ratio of sides of loaded are to bearing area of the prism, f v = transverse tensile stress, f c = average compressive stress in the prism, Pk = applied compressive force on the end block (tendon jacking force), F bst = bursting tension and f v(max) = maximum transverse tensile stress. Strut-and-tie model (STM) is a tool for the analysis, design and detailing of structural concrete members. It is based on truss analogy in which truss members that are in compression are made up of concrete, while that are in tension consist of steel reinforcement. Strut-and-tie modelling (STM) approach is used in application of discontinuity regions in pre-stressed concrete structures. The STM reduces complex states of stress within a discontinuity regions of a pre-stressed concrete member

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C. D. Dipindas et al.

into a truss comprised of simple, uniaxial stress paths. Each uniaxial stress path is considered as a member of the STM. Knowing the forces acting on the boundaries of the STM, the forces in each of the truss members can be determined using basic truss theory. There are three methods for formulating a STM such as (i) elastic method (ii) load path approach and (iii) standard model. However, the load path method is widely used for the development of the STM. In this research, an anchorage zone has been analysed using 2D and 3D strut-and-tie method. In finite element method of analysis, a complex region of a continuum is discretized into simple geometric shapes called finite elements. The material properties and the governing relationship are considered on these elements which are expressed in terms of unknown values at element nodes. Assembling process considers the loading and constraints, resulting in a set of equations. Solution of these equations gives us the appropriate behaviour of the continuum. In this study, analysis of the anchorage zone has been carried out with the help of ANSYS Civil FEM and both 2D and 3D analyses have been attempted. The British code of practice BS 8110 [15] provides a method for calculating the design values of the bursting force Fbst , which is expressed as a fraction of the axial force applied by a tendon to a square concrete end block. In IS 1343 [16] code, it is specified that on the area immediately behind external anchorages, the permissible bearing stress on the concrete, after considering for all losses due to relaxation of steel, elastic shortening, creep  of the concrete, slip and/or br or 0.8 f ci whichever is seating of anchorages, etc. shall not exceed 0.48 f ci AApun smaller, where f ci is the cube strength of concrete at transfer, Abr is the bearing area and Apun is the punching area. As per IS: 1343 [16]. The bursting tensile force F bst is computed using the expression (11). Fbst

 

ypo = Pk 0.32 − 0.3 yo

(11)

where Pk = tendon jacking force, ypo /yo = distribution ratio. IRC Code: 18 [17] specifies the length of end block and in no case shall be less than 600 mm or less than its width. The bursting tensile forces in the end block should be assessed on the basis of the ultimate tensile strength.

3 Analysis of Anchorage Zone In this study, the stresses in the anchorage zone of a post-tensioned concrete girder are analysed using the methods described in the previous section. For this purpose, two examples have been included. The bursting force of an end block with single anchorage has been computed using the Leonhardt’s formula, Magnel’s method, Guyon’s method and method specified in IRC: 18, STM approach and 2D FEM

Analysis of Anchorage Zone Stresses in Post-tensioned …

51

Fig. 1 View of the end block

analysis. Also, finite element analysis of this end block has been carried to study the effect of size and eccentricity of bearing plate and grade of concrete on the anchorage zone stresses. Further, an anchorage zone with multiple anchorages has been modelled using 2D and 3D finite element analyses. A rectangular end block of size 600 × 600 × 600 mm with one pre-stressing tendon has been considered as shown in Fig. 1, constructed with grade of concrete M45 and steel Fe415. The size of the bearing plate used to transfer the pre-stressing force is 214 × 214 mm. The thickness of the bearing plate is 25 mm, and it is subjected to a concentric pre-stressing force Pk = 2204 kN. For the STM to be developed, the model was designed to transfer the pre-stressing force from the anchorage to a distance equivalent to the depth of the end block. In order to model the splitting forces in both the vertical and longitudinal direction of the beam, two STMs were used within the end block. For each STM, the ties were placed at a distance of approximately half the girder depth away from the end face of the end block (300 mm). Also, analysis using 3D STM was also done to model the flow of forces through the discontinuity region instead of the two separate 2D models used to compute the distribution of pre-stressing forces in the horizontal and vertical directions. For finite element analysis, a model was developed in the finite element software ANSYS. The geometry is defined, and the necessary properties of the element had to be given as input as given in Table 1. For applying boundary conditions, the bridge end segments are supported by elastomeric bearings on a concrete pier, so as to prevent the end segment from Table 1 Material properties assumed in the analysis

Concrete properties 1.

Modulus of elasticity

33541.02 N/mm2

2.

Poisson’s ratio

0.16

3.

Density

24 × 103 N/m3

Properties of bearing plate 4.

Modulus of elasticity

2.1 × 105 N/mm2

5.

Poisson’s ratio

0.3

6.

Density

78 × 103 N/m3

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vertical displacement. The other boundary condition that applies to this end segment is symmetry. Finally, the post-tensioning force is applied to the plates on the segment. The bursting stress variation in the vertical direction (y-direction) obtained from the 2D FEM analysis can be seen as compressive near the location of applied prestressing force, and it changes its nature to tensile stress, and it gradually comes to zero at a distance equal to depth of the end block. Figure 2 shows the bursting stress variation along the length of an end block. The maximum bursting force computed using different methods is given in Table 2. From the 2D FEM analysis, it is seen that when the pre-stressing force is applied concentrically on the end block, the bursting stresses are induced between 0.167(2y0 ) and 0.81(2y0 ) along the longitudinal length of the end block as shown in Fig. 2. The position of maximum bursting stresses is located at a distance 0.35(2y0 ) from the loaded face along the longitudinal axis of the end block. This observation on position of maximum bursting stress is close to the value reported by Guyon [13], i.e. 0.33 (2y0 ). The maximum bursting force computed by Magnel’s method and Guyon’s method is quite close, but lower than the value computed by other methods. The maximum Fig. 2 Bursting stress variation along the length of end block

Table 2 Maximum bursting force from the analysis of the end block

Sl. No.

Name of the method

Bursting force in kN

1

Magnel’s method

300.600

2

Guyon’s method

297.385

3

Leonhardt’s method

354.293

4

IRC: 18

469.230

5

3D strut-and-tie model

318.000

6

2D FEM analysis

366.228

Analysis of Anchorage Zone Stresses in Post-tensioned …

53

bursting stress computed by methods given in IRC: 18 and BS: 8110 is 28% higher than the value obtained by the 2D FEM analysis. With increase in the size of the bearing plate, the bursting force/stress gets reduced. The value of the bearing stress is very high, when the size of the bearing plate is below 0.2y0 . Therefore, the minimum size of the bearing plate specified in the code of practice such as IRC: 18 and BS: 8110 is based on the bearing stress criteria and grade of concrete used for pre-stressed concrete bridge construction. The variation of maximum bursting stress with the increase in the size of the bearing plate is shown in Fig. 3. Further, using the 2D FEM analysis of the end block, the variation of bursting stress along the length of the end block and the results are shown in Fig. 4. To study the effect of eccentricity, the loading plate was placed eccentrically at different locations with respect to the longitudinal axis of the end block and stress variation is obtained along a path in the longitudinal direction. In this study, three different values of eccentricity of the bearing plate have been considered in 2D FEM Fig. 3 Effect of size of bearing plate in the bursting stress

Fig. 4 Bursting stress variation for different sizes of bearing plate

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Fig. 5 Effect of eccentricity of bearing plate on bursting stress

analysis. Eccentricities of the bearing plate from the longitudinal axis of the end block are taken as 0.1y0 , 0.2y0 and 0.3y0 for the analysis, where y0 is the depth of the end block. Figure 5 shows the variation in bursting stress with the eccentricity of the bearing plate. When the eccentricity of the bearing plate is 0.1y0 , the variation of bursting stress in the end block is almost same as that of an end block with concentrically placed bearing plate. But when the eccentricity of bearing plate is 0.2y0 and 0.3y0 , the spalling tensile stresses acting on the loaded face are quite high than bursting stresses as seen from Fig. 5. With increase in the eccentricity of the bearing plate, the spalling stress in the loaded face of the end block increases, whereas the bursting tensile stress decreases considerably. For getting the influence of the grade of the concrete in the variation of the bursting stress of the anchorage zone, the same end block has been analysed using 2D FEM with six different grades of concrete such as M35, M40, M45, M50, M55 and M60. The result obtained from this analysis is plotted in Fig. 6. The grade of concrete has negligible effect on the bursting stress distribution of the anchor block. In the 3D FEM model, the pre-stressing force is converted as uniform pressure and applied on the entire area of the bearing plate. The bursting stress variation obtained by 3D and 2D analyses is shown in Fig. 7. Bursting stress obtained by 3D analysis is lower than the values obtained from the 2D analysis.

3.1 End Block with Multiple Anchorages The post-tensioned anchorage zone of an I-girder of the bridge constructed with concrete of grade M45 and steel Fe415 has been analysed using 2D and 3D FEM.

Analysis of Anchorage Zone Stresses in Post-tensioned …

55

Fig. 6 Bursting stress variation for different grades of concrete

Fig. 7 Bursting stress variation obtained from 2D and 3D FEM analyses

The girder has seven cables, and each of them is initially jacked to 2204 kN and is anchored in the zone of rectangular in shape. Depth at the end of the girder is 2300 mm, top flange width is 1250 mm, width of the web is 830 mm and length of the anchorage zone is 2800 mm as shown in Fig. 8. Bearing plates of 214 × 214 × 25 mm size are used for transferring the pre-stressing force. The vertical stress variation of the anchorage zone from 2D FEM analysis is shown in Fig. 9, and the paths for stress variation study are shown in Fig. 10. The comparison of bursting stress variation of the anchorage zone obtained from the 2D and 3D FEM analyses is shown in Figs. 11, 12, 13, 14 and 15. The 2D and 3D FEM analyses results show that the bursting stresses occurring between each bearing plate is less. This may be due to the neutralization of the bursting stresses between the bearing plates as they are acting in opposite direction. However, the spalling stresses acting between the plates are high in comparison with the bursting stresses.

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Fig. 8 Anchorage zone of a girder end

Fig. 9 Vertical stress distribution along different paths

4 Conclusion Anchorage zone is the most important region in a post-tensioned concrete girder. In the anchorage zone, the stresses are complex in nature during the application of pre-stressing forces. There are many factors which influence the bursting stresses of the anchorage zone.

Analysis of Anchorage Zone Stresses in Post-tensioned … Fig. 10 Paths for stress variation study obtained from the 2D and 3D analyses

Fig. 11 Bursting stress variation along the path 1 (as shown in Fig. 10)

Fig. 12 Bursting stress variation along the path 2 (as shown in Fig. 10)

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Fig. 13 Bursting stress variation along the path 3 (as shown in Fig. 10)

Fig. 14 Bursting stress variation along the path 4 (as shown in Fig. 10)

In this research, to study the behaviour of a rectangular end block, different methods such as elastic analysis, Guyon’s method, Magnel’s method and codal provisions have been used. Also, the application of 2D and 3D strut-and tie-model (STM) to compute the bursting force in the end block has been demonstrated. Further, the finite element analysis of an end block has been carried out using the software CIVIL FEM-ANSYS 11. In this FEM analysis, the end block is analysing separately by 2D and 3D models. The influence of the size of the bearing plate, eccentricity of bearing plate and grade of concrete on the stress distribution of the end block has been investigated using finite element method. More complex configuration of an anchorage zone with multiple anchorages in a girder has also been studied. The main conclusions from the studies are given below:

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59

Fig. 15 Bursting stress variation along the path 5 (as shown in Fig. 10)

• The variation of bursting tensile stresses in the end block is parabolic in nature. From the 2D FEM analysis, it is seen that when the pre-stressing force is applied concentrically on the end block, the bursting stresses are induced between 0.167(2y0 ) and 0.81(2y0 ) along the longitudinal length of the end block. The position of maximum bursting stresses is located at a distance 0.35(2y0 ) from the loaded face along the longitudinal axis of the end block. This observation on position of maximum bursting stress is close to the value reported by Guyon [13], i.e. 0.33 (2y0 ). • The value of bursting tensile stress decreases with increase in the eccentricity of the bearing plate. However, the spalling tensile stress increases with increase in the eccentricity of the bearing plate. For the loaded member, greater care should be by providing more reinforcement to resist the spalling stresses than bursting stresses. • With increase in the size of the bearing plate, the bursting force/stress gets reduced. The value of the bearing stress is very high, when the size of the bearing plate is below 0.2y0 . Therefore, the minimum size of the bearing plate specified in the code of practice such as IRC: 18 and BS: 8110 is based on the bearing stress criteria and grade of concrete used for pre-stressed concrete bridge construction. • The maximum bursting force computed by Magnel’s method and Guyon’s method are quite close, but lower than the value computed by other methods. The maximum bursting stress computed by methods given in IRC: 18 and BS: 8110 is 28% higher than the value obtained by the 2D FEM analysis. • The grade of concrete has negligible effect on the bursting stress distribution of the anchor block. • The 2D and 3D FEM analyses results show that the bursting stresses occurring between each bearing plate are less in an end block with multiple anchorages. However, the spalling stresses acting between the plates are high in comparison with the bursting stresses.

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References 1. Tsavalas GJ (1958) An experimental investigations of end block reinforcements in pre-stressed concrete beams. Thesis report paper, submitted to Massachusetts Institute of Technology 2. Marshal WT, Mattok AH (1962) Control of horizontal cracking in the end of pretensioned pre-stressed concrete girder. PCI J 7(5):56–74 3. Gergely P, Sozen MA (1967) Design of anchorage zone reinforcement in pre-stressed concrete beams. PCI J 12(2):63–75 4. Sundra Raja Iyengar KT, Prabhakara MK (1971) Anchor zone stresses on pre-stressed concrete beams. J Struct Div ASCE 97(ST3):807–824 5. Zhongguo (John) Ma, Salesh MA, Tader MK (1999) Optimized post-tensioning anchorage in pre-stressed concrete i-beams. PCI J 56–64 6. Sundra Raja Iyengar KT (1962) 2-dimensional theories of the anchorage zone stresses on post tensioned pre-stressed beams. ACI J 59(10):1443–1465 7. Yettram AL, Robbin K (1969) Anchorage zone stresses in axially post-tensioned uniform member of uniform rectangular section. Mag Concr Res 21(67):103–112 8. Yettram AL, Robbin K (1970) Anchorage zone stresses in post-tensioned uniform member with eccentric and multiple anchorage. Mag Concr Res 22(73):209–218 9. Sarles D Jr, Itani RY (1984) Effect of end block on anchorage zone stresses in pre-stressed concrete girder. PCI J 29(6):100–112 10. Hengprathanee S (2004) Linear and nonlinear finite element analyses of anchorage zones in post-tensioned concrete structures. Thesis paper, September 2004, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 11. Leonhardt F (1964) Prestressed concrete: design and construction. W. Ernst 12. Magnel G (1949) Design of the ends of prestressed concrete beams. Concr Constr Eng 44(5):141–148 13. Guyon Y (1953) Prestressed concrete, V.1, Jointly published by contractors record Ltd., London, United Kingdom, and Wiley. Inc., New York, NY, 239 14. Zielinski J, Rowe RE (1960) An investigation of the stress distribution in the anchorage zones of post-tensioned concrete members, cement and concrete association research report no. 9, p 32 15. British Standards Institute (1985) BS8110, structural use of concrete-Part 1: code of practice for design and construction. Standard, British Standards Institute (BSI) 16. IS 1343: 1980 Code of Practice for Pre-stressed Concrete, Bureau of Indian Standards, New Delhi 17. IRC 18: 2000 Design Criteria for PSC Bridges, The Indian Roads Congress, New Delhi

A Study on Influence of GGBFS as Binder on Bond Strength Behaviour of Reinforced Concrete V. P. Prashanth, H. M. Mahendra Kumar, and G. P. Chandradhara

Abstract The performance of reinforced concrete primarily depends on the bond strength and is defined as resistance to slipping of the reinforcing steel bars from the concrete. This slipping resistance is predominate mode of failure in predicting the mechanical performance of RCC, particularly to its failure mode and adhesion between steel reinforcement and concrete. In the present study an attempt is made to study the bond strength of structural grade concrete (M35) with high strength steel (Fe415) of 12, 16 and 20 mm (Fe500) embedded in the core of concrete. The pull-out test was carried out for various mixes of concrete with an addition of GGBFS as partial replacement with cement (10–30%). Also, attempt is made to evaluate the resistance for slippage, rupture behaviour and stress distribution are studied using finite element analysis tool. The study reveals that the bond strength improves the consideration of mineral admixture and also seems to improve with diameter of reinforcing bars for GGBFS binder-based concrete. The microstructure (SEM) is also evident for the minimal voids and densification with addition of GGBFS as binder, which enhances the bond strength with a partial replacement of cement. The numerical study closely reviews the experimental investigation. Keywords Bond strength · Pull-out test · Steel concrete interphase · GGBFS · Microstructure · FEM

V. P. Prashanth (B) CT&M Department, SJCE, JSSS&TU, Mysuru, India e-mail: [email protected] H. M. Mahendra Kumar · G. P. Chandradhara Civil Engineering Department, SJCE, JSSS&TU, Mysuru, India e-mail: [email protected] G. P. Chandradhara e-mail: [email protected] © Springer Nature Singapore Pte Ltd. 2021 M. C. Narasimhan et al. (eds.), Trends in Civil Engineering and Challenges for Sustainability, Lecture Notes in Civil Engineering 99, https://doi.org/10.1007/978-981-15-6828-2_5

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1 Introduction Concrete is mankind stone which is strong in compression but weak in tension. The tensile strength of concrete is about one in tenth times the compressive strength of concrete. This negative characteristic is remedied by placing steel reinforcing bars into the concrete to form reinforced concrete (RC) where steel can resist higher amount of tensile stress and concrete is designed to resist compressive stress. The performance of RCC primarily depends on the interphase (adhesion) between concrete and the reinforcing steel which must have a sufficient stronger bond, so the tensile load can be transferred effectively to the reinforcement [1]. The high tensile strength of steel is able to withstand the tensile stresses upon failure of the concrete. In order to obtain complete composite behaviour between the reinforcing steel and the concrete, the tensile stresses must be fully transferred to the steel from the concrete. This transfer of stresses is facilitated by an adequate bond between the steel reinforcing bars and concrete. The interphase bond strength primarily depends on strength of cement paste and also depends on the bonding surface area (size of reinforcement) [2]. Based on the literatures, pull-out test [3] is considered for the evaluation of bond strength; an attempt is made to address the contribution of GGBFS as binder for the bond strength improvement.

2 Experimental Methods and Materials The locally and commercially available materials are chosen in the present study as per the provision of Indian standard code practices. a. Binder The OPC 43 grade and finely ground blast farness slag from steel manufacturing industry is used as binding materials. b. Fillers The commercially available M-Sand is used as fine aggregates, and 20 mm down size is considered as coarse aggregate. The physical properties are tabulated in Table 1. c. Reinforcement Fe 500 structural grade steel is used as reinforcing bars with diameters 12 mm, 16 mm and 20 mm embedded centrally in the core of concrete. d. Curing The conventional mixes of concrete and steel reinforced specimen are cured in conventional method of water curing for different ages.

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63

Table 1 Physical properties of aggregates Physical properties

Fine aggregate

Coarse aggregate

Specific gravity

2.57

2.74

Water absorption

1.2%

0.2%

Silt content

2.56%

–

Sieve analysis

Zone II

–

Table 2 Mix proportions per cubic meter of concrete Mix

W/C

GGBFS

Cement

FA

CA

Water

M1

0.45

–

430

M2

0.45

43

387

755

1022

193

755

1022

M3

0.45

86

193

344

755

1022

193

M4

0.45

129

301

755

1022

193

M1 = Cement-based concrete mix M2 = Cement-based + 10% GGBFS concrete mix M3 = Cement-based + 20% GGBFS concrete mix M4 = Cement-based + 30% GGBFS concrete mix

3 Mix Design and Specifications The structural grade concrete with 0.45 water–cement ratio and 430 kg/cum is chosen as binder content for the present study, and 12, 16 and 20 mm reinforcing bars [8] are embedded in the central core of concrete and tested for incremental tensional load for different curing periods. The mix design and provision of reinforcement are followed as per Indian standards. The mix proportion details of structural grade of concrete are abbreviated in Table 2.

4 Results and Discussion The pull-out test is carried out for various types of mixes ranges from M1, M2, M3 and M4. The developments of compressive and tensile strength with age are shown in Table 3. The Fig. 1 depicts the relation between the compressive strength and Age in days for different mixes. From Fig. 1 and Table 3, it can be clearly observe that the compressive strength of concrete of M4 which is cement + 30% GGBFS-based concrete is high compared to the other mixes, there is a significant improvement in the compressive strength of cement replaced GGBFS concrete because of the high pozzolanic nature of the GGBFS and its void filling ability. The early age strength of GGBFS concrete is lower than the ordinary concrete. However, as the age of the

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Table 3 Compressive and tensile test results MIX (Mpa)

Compressive strength

Split tensile strength

7 days

14 days

28 days

7 days

14 days

28 days

M1

34.11

43.79

51.74

2.28

3.00

3.73

M2

29.40

37.47

46.14

1.82

2.19

2.52

M3

27.99

40.44

48.07

1.58

1.95

2.97

M4

34.71

45.68

54.54

2.42

3.13

3.58

Fig. 1 Compressive strength for increasing curing period

concrete is extended beyond 28 days, the increase in strength is higher for the GGBFS concrete. The Fig. 2 depicts the relationship between spilt tensile strength and age in days of the concrete for different mixes of concrete. It is inferred from the graph that the spilt tensile strength of mix M4 is higher compared to other mix concrete because there is a significant improvement in the tensile strength of cement replaced GGBFS concrete because of the high pozzolanic nature of the GGBFS and its void filling ability.

Fig. 2 Split tensile strength results

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5 Bond Strength The concrete specimens were tested in UTM the machine for various ages of curing under the action of pulling load for the resistance of concrete steel interphase. The bond stress can be calculated based on the literature [3–5] τbd = P/(π  Ld) • • • •

τ bd is the ultimate bond stress (MPa)  is the rebar diameter (mm) Ld is the bond length (mm) P is the ultimate pull-out load (N).

The test specimens for bond strength study consist of concrete cubes of size 150 × 150 × 150 mm [6] with a single reinforcing bar embedded vertically along a central axis. The bar shall inserted to a total depth till the bottom face of the cube and shall project upward from the top face for sufficient length for testing of bar to extend through the cubes to provide an adequate length to be gripped for application of load. The UTM is used to apply a tensile load for the steel reinforcement embedded in concrete [7]. The test is carried out for various diameters of reinforcing bars 12, 16, 20 mm with different mix proportions (M1, M2, M3 and M4) and for different ages of curing, and the results are shown in Table 4. The resistance to pull out with the age has been experimentally investigated and presented in graphical representation of bond–slip relation of for different ages of curing, 7 days, 14 days, and 28 days. Table 4 Bond strength (BS) with age of concrete for various mixes M1–M4 with varying size of reinforcement MIX

Day

BS

Slip

12 mm M1

M2

M3

M4

BS

Slip

16 mm

BS

Slip

20 mm

7

7.37

4.36

5.72

4.76

4.8

14

7.97

5.63

6.59

6.47

5.54

28

9.71

7.21

7.93

10.9

6.52

6.29 7.02 11.2

7

6.93

3.74

5.24

4.46

4.57

5.53

14

7.63

5.04

5.72

4.94

5.20

6.74

28

9.13

6.88

7.37

8.36

6.24

8.11

7

6.82

3.95

5.03

4.11

4.3

3.78

14

7.4

4.52

5.76

5.21

5.06

6.08

28

8.9

6.35

7.19

7.45

6.1

8.84

7

7.51

4.32

5.89

5.21

5.2

6.02

14

8.32

5.24

6.76

5.72

6.1

8.78

8.01

8.58

28

10.0

11.9

7.14

12.4

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The development of bond strength and resistance to slippage with age for 16 mm are shown in Figs. 3, 4 and 5 for various mixes of GGBFS. The similar trend is observed for the 12 and 20 mm size reinforcement. The bond strength development follows the same trend for different ages of concrete for various mixes M1–M4, and the typical behaviour is shown in Fig. 3 for 16 mm reinforcing bar. As incorporation, of GGBFS improves compressive strength by 27% with addition of mineral admixture with respect to the Grade of Concrete with age. Figures 6, 7, 8 and 9 represent the slip resistance for various mixes of binder with increase in size of reinforcement. From the Figs. 3–9, the bond strength of mix M1 is one-sixth times of its compressive strength, and bond strength for GGBFS-based concrete is one-fifth times of its compressive strength. The crack growth pattern in the concrete embedded with

Fig. 3 Bond strength for 7 days of curing for 16 mm bars

Fig. 4 Bond strength for 14 days of curing for 16 mm bars

Fig. 5 Bond strength for 28 days of curing for 16 mm bars

A Study on Influence of GGBFS as Binder on Bond Strength …

Fig. 6 Bond–slip relation for Mix M1 with varying diameter of reinforcement for 28 days

Fig. 7 Bond–slip relation for Mix M2 with varying diameter of reinforcement for 28 days

Fig. 8 Bond–slip relation for Mix M3 with varying diameter of reinforcement for 28 days

Fig. 9 Bond–slip relation for Mix M1 with varying diameter of reinforcement for 28 days

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12 mm is less due to smaller the frictional area; it is surrounded by smaller area of concrete. The relative displacement of the bar is always measured with reference to the undisturbed concrete and consists of relative slip at the interface. After attaining the peak value, a sudden drop in the load was observed. The bond strength did not change much with diameter of bars. However, the resistance increased slightly with increase in bar diameter in certain cases. In general, it can be clearly seen that the bond stress of concrete of mix M4 which is cement + 30% GGBFS-based concrete is high compared to the other mixes. a. Influence of Size of Reinforcement on bond strength Charters tics with Age of concrete The Figs. 6, 7, 8, and 9 depicts the relation between the bond stress (N/mm2 ) and slip (mm) for different mixes. It can be clearly seen that the bond stress of concrete embedded with the 12 mm diameter is more compared to higher diameter of the bars due to the load carrying capacity is less compared to other reinforcements. The reinforcement surrounded by the concrete area is less for reduced diameter and hence, the frictional resistance is less thus the reinforcement of 12 mm diameter fails due to stress in steel is more than the frictional resistance compared to 12 mm diameter.

6 Microstructure Study (SEM) The microstructure behaviour of all different mixes of concrete are analysed using SEM. The specimen is collected after each test, and it is immersed in formaldehyde solution to preserve the state of sample and is exposed for SEM for various levels of observations. The samples are analysed using different spectra images taken for 100, 50, 20, 10, 5 and 1 µm for different series of mixes and are presented in Fig. 10. The image shows the microstructure of interfacial zone of the mix M1–M4 where there is small void between the interfacial zone particles after the absorption of water and the ettringite formation in the mortar paste. The interfacial zone of mix M2 which was 10% GGBFS-based concrete, there is void present in the interfacial zone due to the addition of mineral admixture. SEM also evident for the finger-like structure called ettringite which are byproduct of hydration. The voids are minimal in the interfacial zone of mix M4 compared to mix M1 due to the addition GGBFS (30%) replacement also it is evident for un-hydrated state of GGBFS, which may create platform for secondary rate of reaction.

A Study on Influence of GGBFS as Binder on Bond Strength …

a M1

M2

69

b M3

M4

Fig. 10 Microstructure images of various mixes, with GGBFS as binder in RCC

7 Fem Analysis of Pull-Out Test The FEM analysis is carried out using Ansys software. The use of deformed bar increasing bonding between concrete and reinforcing steel bar. The concrete is modelled using SOLID65 eight-node brick element, which is capable of simulating the cracking in tension and crushing in compression behaviour. While modelling, a cube length equal to the required embedded length 150 mm and 12 mm, 16 mm and 20 mm diameter is considered [7]. • BEAM 188 is used for the modeling the reinforcement. • SOLID 65 for concrete. While modelling, a cube length equal to the required embedded length 150, 12, 16 and 20 mm diameter are considered. Extensive use of deformed bar has led us to consider perfect bonding between concrete and reinforcing steel bar. The element edge of length of meshing is given as 15 mm. To obtain precise results in concrete embedded of reinforcement, meshing is done much finer as shown in Figs. 11, 12 and 13 represent the results of numerical analysis in terms of stress distribution.

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Table 5 The particulars considered for material properties for modelling Material element

Parameters

Experimental results

SOLID 65

Compressive strength

46.2 N/mm2

Elastic modulus

29,112.6 Mpa

BEAM 188

Poisson’s ratio

0.2

Nominal diameter

12, 16 and 20 mm

Elastic modulus

2 × 105 Mpa

Poisson’s ratio

0.3

Fig. 11 Loading boundary conditions

Fig. 12 Tensile stress distribution for the 12 mm size of reinforcement

a. Comparison between Numerical and experimental results of the pull-out test The bond stress results are compared between the numerical solutions and the experimental results for the Mix M2 (Table 6). In the case of 12 mm diameter bar, the tensile stress formed due to the applied tensile load and the steel surrounded area by the concrete are less; hence, there is stress formed in smaller area the crack growth pattern is less. The most of stress was taken by the steel. The stress formed in concrete area is high, and the crack growth

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71

Fig. 13 Tensile stress distribution for the 20 mm size of reinforcement

Table 6 Numerical and experimental results bond strength Diameters (mm)

Bond stress (N/mm2 ) Numerical results

Experimental test results

12

13.95

9.13

16

12.48

8.36

20

11.48

8.11

pattern is also higher in the case of 20 mm diameter reinforcing bars. The results of numerical are higher than experimentaly arrived values, and this may be due to material non linearity behaviour considered in the modeling practice.

8 Conclusion The compressive strength and split tensile strength of various mix shows that the mix higher GGBFS of 30% carry higher strength compared to other mixes because to it contains optimum dosage of GGBFS which provides platform for secondary reaction. The bond strength behaviour varied with different ages of concrete, and the declined trend is observed in initial phase. The bond strength increases with increasing compressive strength of concrete with the addition of GGBFS as binder. The bond strength enhances with the maturity of concrete at the rate of 23–27% with the addition of GGBFS as binder, and also, the trend shows that the bond strength decreases in a nominal rate for increasing the dia. of reinforcement. SEM observation is evident for the good quality of the matrix with the addition of GGBFS as binder also evident for secondary reaction for varying sizes of reinforcement.

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References 1. Zuo J, Darwin D (2000) Splice strength of conventional and high relative rib area bars in normal and high-strength concrete. ACI Struct J 4:630–641 2. Noushini A, Caste A, Dahou Z (2016) Prediction of the steel-concrete bond strength from the compressive. Constr Build Mater 119:329–342 3. Appa Rao G, Pandurangan K, Sultana F (2000) Studies on the pull-out strength of ribbed bars in high-strength concrete. Indian Institute of Technology Madras 4. Bouazaoui AL (2007) Analysis of steel/concrete interfacial shear stress by means of pull out test. Int J Adhes Adhes 28:101–108 5. Shena D, Shi X, Zhang H, Duan X (2016) Experimental study of early-age bond behavior between high strength concrete and steel bars using a pull-out test. Constr Build Mater 119:653– 663 6. Kabir R, Islam MM (2014) Bond stress behavior between concrete and steel rebar: critical investigation of pull-out test via finite element modeling. Int J Civ Struct Eng 5:80–90 7. Lakshmaiah CP, Khutubuddin KS, Vinayaka B, Saikiran D, Induja Y, Narasappa Y, An experimental study on cement replacement by GGBFS in concrete. Int J Innov Res Sci Eng Technol (IJIRSET) 6:5966–5973 8. Ramamrutham S (2008) Design of reinforced concrete structures. Int Sch Sci Res Innov 9:355– 358 9. Dahou Z, Castel A, Noushini A (2016) Prediction of the steel-concrete bond strength from the compressive strength of Portland cement and geopolymer concretes. Constr Build Mater 329–342 10. IS: 456-2000, Code of practice for plain and reinforced concrete. Bureau of Indian Standards, New Delhi 11. IS: 10262-2009, Concrete mix proportioning—guidelines. Bureau of Indian Standards, New Delhi 12. IS 2770:1967, Indian Standard Code of practice for method of testing bond in reinforced concrete. Bureau of Indian Standard, New Delhi

Comparative Studies on Flexural Strength of Conventional and Alkali-Activated Masonry Elements Designed to Field Mix Sahithya S. Shetty, Shriram Marathe, and I. R. Mithanthaya

Abstract Due to degradation and non-availability of the natural resource, a numerous research is under taken to find a sustainable and eco-friendly construction material. One of the ways to achieve this is by replacing the major materials of the normal cement concrete, completely or partially with different materials using low cost, easily available industrial by-products or waste material. Considering all these facts, the present study focuses on an alkali-activated cement with the complete substitution of conventional cement binder with GGBS, fly ash and glass powder for the production of standard solid masonry blocks of standard size. In the study, locally available quarry dust is used as fine aggregates as a complete substitution of river sand. This investigation is aimed to study the strength aspects such as compressive strength, split tensile strength and flexural strength of the masonry blocks as per IS 2185-1-2005. As per the results obtained, it is revealed that alkali-activated concrete masonry blocks have superior strength aspects when compared to OPC concrete masonry blocks. Keywords GGBS · Fly-ash · Alkali activation · Compressive strength · Tensile strength · Flexural strength

S. S. Shetty (B) · S. Marathe · I. R. Mithanthaya Department of Civil Engineering, NMAM Institute of Technology, Nitte, Karkala, Udupi, Karnataka 574110, India e-mail: [email protected] S. Marathe e-mail: [email protected] I. R. Mithanthaya e-mail: [email protected] © Springer Nature Singapore Pte Ltd. 2021 M. C. Narasimhan et al. (eds.), Trends in Civil Engineering and Challenges for Sustainability, Lecture Notes in Civil Engineering 99, https://doi.org/10.1007/978-981-15-6828-2_7

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1 Introduction Masonry blocks are the individual building units of a building. The two common types in masonry blocks are burnt brick and concrete block. But these types of masonry blocks are not preferred as they are not sustainable. The production of burnt bricks requires a vast quantity of fossil fuels and fertile soil. And the conventional ordinary Portland cement concrete (OPC) blocks which uses cement have a lot of drawbacks. It is a well-known fact that CO2 is produced during the production of OPC which has led to global warming and greenhouse effect [1, 2]. It is reported that by 2020, in India, the total demand for cement will reach 550 million tons with a shortage of 230 million tons which is approximately 58% [1]. The manufacturing process of OPC emits CO2 which is estimated to be 7% (approx.) of the total worldwide emissions which are causing global warming. A total of 4 GJ of energy is consumed, and approximately 0.85 ton of CO2 is emitted into the atmosphere during the production of one ton of OPC. The amount of energy consumed during the manufacture of OPC is approximately 10% of the total energy used. These percentages are increasing gradually day by day. Hence, there is requirement of other alternatives to cement concrete blocks, and this has led to the development of alkali-activated concrete. In alkali-activated concrete, fly ash, ground granulated blast furnace slag (GGBS), metakaolin and natural pozzolanic, etc., are used as cementitious materials instead of OPC binders. The alkali-activated binder is usually industrial by-products which have superior properties when compared to OPC binders and also of lower cost. In alkali-activated concrete, silica and aluminium rich source are used as binders which are activated using liquid alkaline solution. The most commonly used compounds used for the alkaline liquid are MOH and M2 O rSiO2 , where M is either Na or K. The activator liquid accelerates early strength development and improves mechanical properties. The overall cost for the production of OPC solid masonry block has increased due to the increase in demand and cost of OPC binders and also due to the unavailability of sand. This has resulted in the research of alternative options for masonry blocks [3–5]. One of such alternate is alkali-activated cement which has many advantages over Portland cement such as reduced heat of hydration, high early strength and high resistance to acid and sulphate aggressive conditions [6, 7]. A solid alumino silicate powder reacts with alkali hydroxide/alkali silicate to produce alkali-activated cement. The two main constituents of alkali-activated cement are the source material and an alkaline solution. The materials which are rich in silicon (Si) and aluminium (Al) are used as source material. The source material is usually easily available materials like fly ash, silica fumes, rice husk ash, etc., which are usually the by-products of major industries. The alkaline liquid is basically a soluble alkali metal that is sodium- or potassium-based. Fly ash is a waste material produced during burning of coal in thermal power plants. Ground granulated blast furnace slag (GGBS) is produced from the blast furnaces which are used to make iron. The chemical composition of GGBS underwrites to the production of superior cement. GGBS significant attribute of providing

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ultimate strength when added to Portland cement makes it the preferred material in the construction of high-rise buildings, marine applications such as dams, shore protection construction, effluent and sewage treatment plants, cement products such as tiles, pipes and blocks Sand is the most extricated materials on the planet by weight, and since these items take a huge number of years to shape by disintegration, request is starting to exceed supply. There is a demand for alternative material for the replacement of sand. Quarry dust is a by-product of crushing process of rock. The vast majority of the creating nations are experiencing tension to supplant fine total in cement by a substitute material additionally somewhat or absolutely without bargaining the nature of cement. Quarry dust has been utilized for various exercises in the development business, for example, building materials, street improvement materials, totals, blocks and tiles. In this project, GGBS and fly ash are used for the complete replacement for the Portland binders and use of quarry dust instead of river sand. This reduces the expense of masonry building blocks can be decreased. The emanation of carbon dioxide is likewise can be decreased because of decrease in utilization of Portland concrete, and the powerful utilization of modern waste materials is accomplished. In this manner, an endeavour is made to examine and to create masonry building blocks utilizing non-traditional antacid initiated bond concrete without bargaining the quality and strength properties. In the current examination, the compressive strength, spilt tensile strength and flexural strength of the masonry brickwork created utilizing soluble base actuated bond are displayed.

2 Methodology The fundamental target of this test work is to evaluate the total substitution of common Portland bond by the GGBS and fly ash as the total substitution of river sand by quarry dust and to look at its compressive strength, split tensile strength and flexural strength with the conventional masonry block. The conventional OPC masonry blocks were procured from a masonry block manufacturing factory named Sri Parameshwari Industry, Pilar. For the production of conventional OPC masonry blocks, equal amount of coarse and fine aggregate was used. For the alkali-activated concrete masonry block, the locally available quarry dust is used as fine aggregates in place of river sand. The quarry dust used has a specific gravity of 2.67 and passing through 4.75 mm sieve. Likewise, the stones available in the local quarry dust are used as coarse aggregate. The stone aggregates used are finer than 10 mm and have 2.72 specific gravity. Equivalent quantity of both fine and coarse aggregates was used for the mix proportions. The fly ash used belongs to Class F type which was procured from UPCL thermal plant, Padubidri. The fly ash had a specific gravity of 2.16. The GGBS used was obtained from the local supplier of JMFC cement. Specific gravity of GGBS was observed to be 2.89. Accessible portable water was utilized for mixing. Water cement ratio of 0.45 was adopted.

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Visit was made to the local factory where OPC-based masonry block is manufactured and the mix proportions were legitimately acquired. In the mix proportion, the cement binder and the aggregate mixture were taken in 1:5 ratios [5]. In the experimental work, three mix proportions are used namely M1, M2 and M3. The first mix say M1 is portrayed for the OPC-based masonry block. For the production of alkali-activated concrete, orderly adjustment was done based on literature studies. The binders used are GGBS, fly ash and fine glass powder [8]. The percentage of GGBS used was 75% by weight of the total binder in the both mixes. In the second mix, say M2, fly ash was used as 25% by weight of binder, and in third mix, say M3, 25% of glass powder was used. The strength behaviour was studied by conducting compressive, split tensile and flexural test on the masonry block.

2.1 Preparation of Masonry Units First, the dry mix is prepared in the mixer with the calculated amount of coarse aggregate, quarry dust and cementing material. After the dry mix is mixed properly, the calculated amount of water is added, and then, it is mixed properly for 5 min. Moulds of size 400 mm × 200 mm × 150 mm are used. The wet mix is then filled in the moulds and then vibrated, compacted and finished (Fig. 1). The blocks were demoulded after 24 h and then air cured in room temperature. After the curing period, the blocks are tested. The OPC-based site mix blocks were water cured before testing [9, 10] (Fig. 2).

Fig. 1 Sample of masonry blocks in its fresh state

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Fig. 2 Demoulded masonry blocks kept for curing in our laboratory

2.2 Tests Conducted on Masonry Units All the tests on the masonry block were carried in the concrete material testing laboratory of NMAMIT, Nitte. The compressive strength test is conducted after 28 days air curing. Figure 3 shows details of compression test of masonry block specimen.

Fig. 3 Compression test on masonry units

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Fig. 4 Spilt tensile test on masonry units

The split tensile test details are shown in Fig. 4. Testing of masonry specimens for spilt tensile strength is appeared in Fig. 5.

Fig. 5 One-point bending test on masonry units

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COMPRESSION STRENGTH OF MASONRY BLOCK

COMPRESSION STRENGTH, MPa

30

27.52

25 20 16.16 15

12

10 5 0

M1

M2

M3

MIX DETAILS

Fig. 6 Compression test results of the masonry blocks

3 Results and Discussion 3.1 Compressive Strength The results of compressive strength done on the cured masonry blocks are shown in Fig. 6. The results reveal that the alkali-activated mix M2 showed better performance when compared to other two mixes. Unmistakably, the substitution of ordinary Portland binder with alkali-activated binder for the production of masonry brickwork resulted in the increment of compressive strength significantly. The mix M2 and mix M3 showed an increment of 130 and 34% in compressive strength when compared to conventional concrete block, i.e. mix M1. Figure 7 demonstrates the failure pattern of compressive strength test

3.2 Split Tensile Strength Figure 8 shows the split tensile test results after curing for 28 days for all the three mixes. The values shown in the figure are the average value of compressive strength of three different specimens. Essentially, as to compressive strength, from Fig. 6, it very well may be seen that the split tensile strength for the mix M2 and mix M3 showed an increment of 147%

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Fig. 7 Failure pattern of masonry block in compression test SPLIT TENSILE STRENGTH OF MASONRY BLOCK

SPLIT TENSILE STRENGTH, MPa

1.6

1.48

1.4 1.2

1.1

1 0.8 0.6

0.62

0.4 0.2 0

M1

M2 MIX DETAILS

M3

Fig. 8 Results of split tensile strength test on masonry blocks

and 84% in compressive strength when compared to conventional concrete block, i.e. mix M1. Figure 9 demonstrates the failure pattern of spilt strength test.

3.3 Flexural Strength Figure 10 shows the flexural strength masonry block after curing for all the mixes, i.e. M1, M2 and M3. The figure showed the average flexural strength for the three different mixes. For the OPC block, the average flexural strength is 1.12 MPa.

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Fig. 9 Failure pattern of masonry block in spilt tensile test FLEXURAL STRENGTH OF MASONRY BLOCK

FLEXURAL STRENGTH, MPa

2.5

2.23 1.89

2

1.5 1.12 1

0.5

0

M1

M2 MIX DETAILS

M3

Fig. 10 Results of flexural strength test on masonry blocks

The flexural strength for mix M2 was seen to be more when compared with M1 and M3. The flexural strength increases of 99% for M2 and 69% for M3 when compared with the conventional concrete masonry block, i.e. M1. Figure 11 shows the failure pattern of compressive strength test.

3.4 Cost Analysis The cost analysis conducted for both the conventional and alkali-activated concrete masonry blocks is shown in Table 1.

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Fig. 11 Failure pattern of masonry block in flexural test

Table 1 Cost analysis of conventional concrete per metre cube Sl. No.

Particulars

1.

Cement

450

7

3150

2.

Fine aggregates

623

4

2490

3.

Coarse aggregates

1084

1

1084

Total amount = Rs.

Quantity (kg)

Rate (kg)

Amount (Rs.)

6700/m3

The cost analysis conducted for both the conventional and non-conventional concrete brickworks indicated the conventional OPC-based concrete block will be 18% costlier than the non-conventional alkali-activated mixes. Hence, alkaliactivated concrete can be effectively used producing the masonry blocks (Table 2). Table 2 Cost analysis of alkali-activated concrete per metre cubic Sl. No.

Particulars

Quantity (kg)

Rate (kg)

Amount (Rs.)

1.

GGBS

330

4.8

1584

2.

Fly ash/glass powder

110

–

–

3.

Coarse aggregates

1281.47

1

1281.47

4.

Quarry dust

658.74

–

–

5.

Sodium silicate

15.3

50

765

6.

Sodium hydroxide (NaOH)

2.3

90

207

Total amount = Rs. 3800/m3

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4 Conclusion The following conclusions were drawn from the present investigations conducted on the masonry blocks. • The two subjects considered here are conventional OPC-based masonry blocks and alkali-activated masonry blocks. • The comparison between the two subjects is done based on their strength characteristics such as compressive strength, split tensile strength and flexure strength. • The maximum values for compressive strength, split tensile strength and flexural strength near to 27.52 MPa, 1.48 MPa and 2.23 MPa, respectively, were shown by alkali-activated masonry specimen which is much higher when compared to OPC masonry blocks. • As alkali-activated masonry blocked was produced using industrial by products, it is 18% cheaper than OPC masonry block. • Thus, alkali-activated concrete can be used as a sustainable and eco-friendly alternative instead of normal conventional concrete masonry elements produced using ordinary Portland cement. Acknowledgements All the specimens were casted in the new-research laboratory of the Civil Engineering Department, NMAM Institute of Technology, Nitte. Authors would like to convey their humble appreciation to the authorities of these institutions for the permission and support provided during the experimental work. Authors thankfully acknowledge the financial support provided by Nitte Education Trust, i.e. NMAMIT research fund on the project entitled “Study and to Develop Cost Effective and Green Masonry Block Using Industrial Waste Materials”.

References 1. Jaarsveld JGS, Van Deventer JSJ, van Lukey GC (2002) The effect of composition and temperature on the properties of fly ash- and kaolinite-based geopolymers. Chem Eng J 89(1–3):63–73 2. Davidovits J (1998) Soft mineralogy and geopolymers. In: Proceedings of the of geopolymer 88 international conference, The Université de Technologie, Compiègne, France 3. SP 20 (S & T) (1991) Handbook on masonry design and construction, 1st revision. BIS, New Delhi 4. Palankar N, Ravi Shankar AU, Mithun BM (2015) Air-cured alkali activated binders for concrete pavements. Int J Pavement Res Technol 08(04):289–294 5. Mithun BM, Narasimhan MC, Palankar N (1991) Strength performance of alkali activated slag concrete with copper slag as fine aggregate exposed to elevated temperatures. Int J Earth Sci Eng 08(02):519–526 6. Chandra S (2002) Waste materials used in concrete manufacturing. Standard Publishers Distributors, Delhi 7. Curtin WG, Shaw G, Beck JK, Bray WA (1999) Structural engineers’ manual, 3rd ed revised by David Easterbrook

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8. Bajad MN, Modhera CD, Desai AK (2012) Higher strength concrete using glass powder. J Struct Eng 39:380–383 9. IS 2185 (2005) Code of practice for concrete masonry units-specifications, Part 1, 3rd revision. BIS, New Delhi 10. Dayarathnam P (1987) Brick and Reinforced brick structures. Oxford and IBH Publications

The Impact of Buildability Factors on Formwork in Residential Building Construction M. Sona

Abstract Improving productivity, increasing output for the same inputs have been a longstanding concern of the construction industry. The different approaches to improving labour productivity in formwork will be briefly explained. The influence of the buildability elements on formwork labour out of key in situ reinforced concrete factors such as foundations, walls, columns, beams and slabs is yet to be gritty and quantified. The key results of several questionnaire surveys will be presented, and the major deterrent to improve buildability and by which buildability problems are being overcome are identified. Keywords Formwork · Labour productivity · Buildability factors · Construction industry · Concrete elements

1 Introduction 1.1 General Construction industry is one of the vast industries as well has a risk involving high hazard industry, which comprises different set of activities, which involves construction, alteration and repair, road paving, large-scale painting jobs, etc. This industry is generally categorised into three categories namely • Structure regarding dense and civil engineering: the production of massive tasks which includes bridge, road and many others comes under this class. • General construction: The works that involve constructing of actual estate ones which include housing or industrial real property belongings, etc.

M. Sona (B) Department of Civil Engineering, NMAM Institute of Technology, Nitte, Karkala, Udupi, Karnataka 574110, India e-mail: [email protected] © Springer Nature Singapore Pte Ltd. 2021 M. C. Narasimhan et al. (eds.), Trends in Civil Engineering and Challenges for Sustainability, Lecture Notes in Civil Engineering 99, https://doi.org/10.1007/978-981-15-6828-2_8

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• Construction initiatives concerning uniqueness trades: Works that involve constructing of specific objects such as electric powered associated works, works on woods, work on mass formwork and so forth. Amongst other trades sectors, construction is the largest sector, which accounts for more than 11.5% of GDP, and it is predictable to raise to 13% by 2020 [1], but there are many underlying challenges in this industry which needs to be addressed, such as productivity, profitability, performance, labour and sustainability, these challenges could derail the construction industry. Productivity is traditionally measured in terms the ratio of output to inputs used in a production process. Productivity as a tool in construction trade is used to quantify the performance of manufacturing. Efficient control of production sources can lead to higher productiveness which can assist to obtain cost and time saving. Decreasing productiveness of challenge has usually been primary issue for construction Industry. Construction industry is associated with money, material, machinery and manpower. Productivity can be enhanced by manipulating cost variance or material adjustment or advanced machinery or using skilled labour. Construction performance and its productivity improvement are the area to be focused in construction industry for any nation. In any multimillion-dollar production project, even a small growth in productivity can yield tens of millions of bucks in additional profit, safer and more efficient work environment.

1.2 Overview of Formwork Formwork is transient or everlasting moulds to which concrete or comparable substances are poured. With the reference to concrete construction, the falsework supports the shuttering moulds. Formwork involves different types namely formwork for foundation, shuttering/formwork for ceiling, wall formwork, beam shuttering and column formwork. Slab formwork which is a form of wall formwork where in timbers is arranged vertically to which metal sheets are pinned on the concrete side. Generally, 2 × 2 or 2 × 4 size sheets are used for slab shuttering. Steel sheets are widely used as due to their wide advantages. Labour productivity, also called team of worker’s productivity, is defined as real economic output in step with exertions hour. Growth in exertions productiveness is measured by the exchange in monetary output in keeping with hard work hour over a described duration. There are many factors which effect labour productivity in formwork, but buildability is one of the important factors.

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1.3 Buildability Buildability is seen since from mankind started erecting simple shelters making use of available materials and simple handmade tools. However, the term buildability is seen in language in the late 1970s. CIRIA (Construction Industry Research and Information Association) in 1983 defined buildability as ‘the extent to which the design of a building can facilitate ease of construction, subject to the overall requirements for the completed building’ [2]. Some of the factors of buildability are as follows: Labour’s skill, supervision, level of complexity, working duration, type of material used, gang size, site layout, availability of power tools, proportion of work done by subcontractor, etc.

2 Reviews on Impact of Buildability Factors on Formwork in Residential Building Construction In general, productivity is measured as ratio of out to input wherein human resource and their part in productivity are also important to be considered. Kulkarni and Devalkar [3] made an attempt to asses and understand the role of ergonomics in various tasks in construction industry and also to find the level of musculoskeletal disorders (MSDs) and cumulative trauna disorder (CTD) and suggest corrective measures for every task having a high risk factor. Two methods such as Rapid Upper Limb Assessment (RULA) and Rapid Entire Body Assessment (REBA) methods were used, to quantify the amount of fatigue experienced by the workers. The study was carried on excavation, centering, tiles work and marble polishing work. The outcomes of these assessments indicate an extreme risk of developing disorders such as CTD and also MSDs and has to be investigated further [3]. de Carvalho et al. [4] this research paper highlights the capacities of lean elements in the course of a constructing’s life cycle. Systematic review process was done according to: planning, conducting the review and results reporting and dissemination. Soon after reporting results, six synergies have been maximum often mentioned they are waste-reduction, reduced value and lead time, improved cost advent, optimized useful resource use, reduced electricity consumption and advanced health and safety [4]. Soumya and Nishara Parveen [5] this paper makes an attempt to identify influence of major factors of buildability involved in formwork, steel fixing and concreting. Data of relevant factors influencing labour productivity was collected from several construction site. Collected data was analysed using SPSS software where least square method was adopted. Outcomes show a relationship between the various factors of buildability with productivity. Factors which are considered were variability of beam size, usable floor area, slab panel floor index, beam floor index, number of beam intersections, floor configuration criteria and floor perimeter geometry [5].

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Lee et al. [6] this paper aims to provide new planning approach with integrated software. Comparative study between harmony search algorithm (HSA) and genetic algorithm (GA) was carried using data such as spacing around vertical members, layout regions. Autocad was used to generate layout regions and generate grid on each region and optimized coordinates on the floor plan. Comparative analysis between GA and HSA derived than an applying compatible algorithm provides better solution in both quantitative and qualitative [6]. Li et al. [7] the goals of the research work is (1) to examine the volume of implementation of the lean creation in China, (2) to explore the factors of lean construction influencing in China’s creation firms. Data is arrived from the interviews, questionnaires and conferences. Examination of this lean construction implementation involves the Transformation Flow Value (TFV) version can explain the primary notion of lean production. The concept of T (transformation) involves the input and output strategies. Its attention is to attain cost-added sports. F (Flow) approach details and cloth float, and it stresses to lessen non-cost-delivered activities. V (Value/cost) way which involves the route of reaching the customers’ necessities, and it stresses to grow the task’s price. The results of this research paper consist of: (1) exclusive firms that have distinctive implementation degrees of lean creation, and (2) the key findings of lean production implementation in China are the know-how of lean creation, organizational shape and culture and market factors [7]. Belayutham et al. [8] this research observes for seamlessly development of the manufacturing, with reference to time, cost and environmental (sediment pollutants) variables via uses the idea of lean production system efforts in achieving an earthworks activity with much clean. Case study on the project located at Rauls, a place in Malaysia, is considered where a lean methodology proposed by ‘Womack and Jones’ that mixes special statistics series techniques (interview, statement, Website report) are used. Findings of the observe, recommend lean allows smooth. Improvements with reduction of time component of 42% and price component of 24% were seen. Rainfall erosivity an environmental factor was reduced to 41.8%, thereby soil erosion and also sediment production are decreased [8]. Ko and Kuo [9] the objective here is to use manufacturing strategies of lean to formwork in order to lessen waste. Case study is carried, in which the waste elements are identified using a lean tool (value streaming), and a lean construction model is adopted in which Andon culture is used to establish an on-Web page pleasant manipulate lifestyle, making workers of shuttering to achieve help immediately each time when trouble takes place. Adding to this, operations of formwork are drawn through the Kanban method in order to decrease mould stock and attain uninterrupted production waft. Improving formwork exceptional relies upon on adopting a tradition of continuous getting to know and improvement. With the Andon way of life and Kanban gadget, waste can be eliminated [9]. Boopathi and Kalidindi [10] this paper aims to examine the effect of usage of equipment on labour productivity during the period of 1997–2014 for 40 different types of construction activities under various categories. Data on labour and equipment coefficient for this research were collected from the Central Public Works

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Department (CPWD) Analysis of Rates for Delhi (DAR). Data from DAR 1997 and DAR 2014, latest version made by CPWD, was considered for the study. It was observed that mean percentage increase in labour productivity from 1997 to 2014 is 23.88% which inferred as increasing equipment input can improve labour productivity in Indian construction industries [10]. Youssouf et al. [11] this paper contributes to optimize the strategy of maintenance of industrial system by applying lean six sigma. The objective of this paper is to improve the quality and profitability of an organization. This statistical process involves five steps (DMAIC), i.e. • Define: clarifying the project issues and recognize customer anticipations to established project goals • Measure: gathering necessary information of measureable constraints of methodology • Analyse: analyse data and find the root cause and find the solution • Innovation: It refers to the action plan of action describing the operation for taken solution control the process • Check: To make sure the problem is solved. By using this statistical maintenance method of five phases, good results in case of profits and also quality can be gained [11]. Ahmed et al. [12] this research objective is to identify the basic benchmarks for sustainable formwork system. Sustainable construction goals to imply the sustainable improvement precept to construction enterprise using imparting methods of the buildings that use much low virgin fabric and low power, cause low pollutants and much less waste but nevertheless give the blessings that construction activities have introduced us during records. This study identifies the benchmark of sustainable formwork that be divided into three primary classes: environmental including (waste era, using renewable material, formwork reusable and material efficiency), economic along with (installation price, cost in-use, life cycle price and formwork serviceability) and social which include (safety evaluation and protection layout of formwork system, direct employment and fire resistance) [12]. Jarkas [1] here, the project paper aims to determine the surface area of wall and also perimeter geometry effect labour efficiency in formwork. Data was collected from 36 constructions sites which include residential, offices structures, profitable centres and not but the least manufacturing amenities. Voluminous data was collected, and statistical analysis was done through regression method. Results of this research establish a noteworthy impact of factors of buildability on formwork work that enhances their efficiency. This results were made to produce an nominal planning and also for effective usage of labours by managers of construction filed [1]. Zin et al. [13] this paper discusses and determines the elements that lead to formwork system in responsive manner. The necessary data collection is done through

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questionnaire survey carried in different construction parts of Malaysia, and questionnaire had been divided into three parts they are demographic respondents, identify factors for the system of formwork and response for sustainability. The sustainable elements identified in this paper through questionnaire survey are classified in terms of environmental elements, social elements and economical elements. Social elements being: highly resistance to change of climate, environmental liable for system of working, absorption of sound, decline consumption of energy, manufacture non-toxic waste, conserve natural resource, reprocess formwork, minimal waste, solid waste, etc. The social elements being: fire resistance, better thermal insulation, branded and patented, anti-insects and vermin, etc. Economical elements are high durability, low cost energy use, speed of construction time, low maintenance, lightweight system, reduce labour cost, etc. [13]. Al-Zwainy et al. [14] this paper aims to develop productivity in construction by assessing a marble finishing model of floors. A set of hundred figures of information was placid at a place of Iraq which included data from residential, commercial and educational projects, and procedure of multivariable linear regression was used in order to create the model. Results in this paper say that the explanatory variable considered proved to be the best predictors in finishing marble floor work. Coefficient of determination R2 is 0.8213 which directs it as a good relation between independent and dependent variables [14]. Ahmed et al. [15] this paper emphasizes the position of system of formwork and its stimulus in order to attain sustainable structure. Survey questionnaires have been dispensed amongst construction professionals and were given 240 respondents with experienced background. The feedback form consists of sections. The first section became covering the respondent background and experience at the same time as the second phase was inquiring about the prominence of the form work gadget in accomplishing sustainable structure. As per this questionnaire survey, 50% of plaintiffs said that they decide that kind of formwork system is disturbing at the sustainability of the project, and 39.5% have been sounded approximately that, thus, the formwork system recollects by way of a crucial element which has its impact at sustainable production [15]. Vieira and Cachadinha [16] this paper aims at contributing to the assessment of the relationship and complementarities between sustainability and LC concepts and standards. This paper portrays a case, that looks at in which lean construction tool and strategies in which carried out on a construction site, so as to observe and verify the connection and complementarity between those and the Sustainability Construction Index (SCI) advanced by using a chief Portuguese Construction Company at Soares da Costa Construcoes (SDC). The site was at once observed in the course of a duration of 1 month, wherein a statistics collection becomes carried out through direct observation, document analysis (made available with the aid of the organization), meetings on Website online with the heads of the undertaking, methodology used is based on the five steps that compose the VSM in this work, and it becomes possible to establish that there is a relationship amongst lean and sustainability. Through the

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utility of lean tool in the construction procedures of a case examine, it was viable to establish a parallelism amongst SCI metrics and lean [16]. Jarkas [2] this research paper approaches to establish the buildability elements that as an impact on productivity of labours at micro level in formwork for beam structures in floors. Information for analysis was collected through site surveying done at 39 different construction sites. The approach for site data collection was done through two folds 1. Exploring the effects of buildability factors 2. Quantifying the factors influencing at micro level. Details were analysed by categorical regression method. As a result, the main influencing buildability elements were identified as a beam repetition size, interactions and span geometry. It shows labour productivity increase by 0.08 m2 /mh for an increase in formwork area straight by 1.00 m2 . Few numbers of larger beam size increase as the efficiency of forming operation [2]. Jarkas [17] this research paper is to compute the effect and virtual influence of the factors of buildability of the following: 1. Depth of edge formed slab 2. Geometry factor for slab 3. Material used type for formwork. Information regarding productivity in labour was collected from 68 different sites where RCC type is used. The information was analysed using multiple categorical regression method of analysis. The results of this research show a significant effect of influencing buildability elements such as edge formwork influencing labour productivity which have helped the construction managers for planning the activity efficiently and using the labours effectively [17]. Jarkas [17] paper intents to measure the intense of influence and effects of grid patterns, variations of foundations sizes, surface area of isolated foundation on labour production. Large set of data was obtained through micro and macro levels in site investigation representing labour productivity which was analysed through regression model, and results were discussed: Grid pattern =

Total no of foundations Total no of foundation axes

Results disclosed the factors of buildability determined are statistically important, and the concepts link with rationalization of design and show the hypothesized effects of all those factors on construction production [18]. Jarkas [17] this project aims to quantify the effects and relative influence of the various buildability factors such as beam size, repetition of floor layout, beam floor area ratio and of curved beam sizes. The required labour productivity data was placid

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from different construction sites. Data was statistically analysed by multiple categorical regression model to determine the connection for productivity of formwork labours in structural floors. Outcomes reflected a greater influence of buildability factors where beam floor area as the highest influence on labour productivity [19]. Huang et al. [20] the objective of this paper is to organize better plan for gang forming construction and to facilitate modular formwork system. Simulation techniques through computer process are used in this paper. CYCLONE system is applied to create computer-oriented models. Five forms of schemes for reuse are identified they are SR, MR/CS/FS, MR/CNS/FS, MR/CS/FNS, MR/CNS/FNS, these forms help to have effective planning and to analysis gang formwork operation which also measures productivity [20].

3 Research Methodology and Analysis In order to minimize the negative influence and disruption on labour productivity, responsibility for slab formwork was taken into consideration, hence labour inputs for slab formwork were collected from 37 different residential construction sites residing in Mysore district, this information collected was analysed, and it is possible to attain reliable and statistical results. After reviewing certain buildability factors of formwork such as numbers of usage cycles of formwork material, number of working hours of labours per day, count of skilled labours, count of semiskilled labours, duration taken for erection, duration taken for stripping, total gang size and area completed per day were listed, and data inputs were collected. Labour productivity was quantified by Formwork area completed per day . All these factors are subjected to multiple regression analLabour input ysis; in statistical modelling, regression analysis is a fixed of statistical methods for estimating the relationships amongst variables. It consists of many techniques for modelling and reading numerous variables, when the point of interest is on the relationship between an established variable and one or more impartial variables (or ‘predictors’). More especially, regression analysis helps one understand how the standard fee of the structured variable (or ‘criterion variable’) modifications when anybody of the unbiased variables is numerous, even as the alternative impartial variables are held constant. Regression is a way used to model to examine the relationships between variables and often times how they make a contribution and are related to producing a selected final result together. Here, regression analysis is made use to determine which are the prime factors affecting the variation of labour productivity in slab formwork.

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4 Discussion of Results The effect and virtual influence of the various factors of buildability were examined by means of regression relationship by carrying a statistically significant test at significance level of 5%. Table 1 presents the correlation value, i.e. multiple R as 92% which is too high value means there is high correlation between dependent and independent value, and Table 1 also gives coefficient of determination value, i.e. R square value as 85% which tells 85% of variation of reliant variable could be explained by non-reliant variables. After examining eight buildability factors four amongst them have proved to have significant impact on productivity of labour of slab formwork amongst them area of formwork surface completed stands 1st followed by count of skilled labours, count of semiskilled labours and gang size. The quantity to which the statistics disagree with the null hypothesis, i.e. the regression coefficient of the corresponding buildability issue inside the regression model is insignificantly specific from zero, consequently its effect on labour productivity is statistically insignificant, becomes decided by the p-value received for each thing investigated. If p-value of the corresponding factors is smaller than 0.05, null hypothesis is rejected, and it is said to have more significant value, smaller the value greater its significance. Table 2 gives the p-value of each factor examined where each factor has its p-value less than 0.05. Table 2 presents the regression coefficient of various factors wherein the negative value of factor is statistically insignificant but also affects labour productivity, i.e. an increase of semiskilled by one reduces the productivity by 0.001%. Graphs 1, 2, 3 and 4 predicts the best probable labour productivity which can be achieved for the particular surface area of formwork, skilled labour, semiskilled labour and gang size. Graph 5 discloses that the various values fit to nearly normally distributed populaTable 1 Statistics of regression model for labour productivity of labour for slab formwork Multiple R

0.925686065

R Square

0.856894692

Adjusted R square

0.813582088

Standard error

0.494114975

Observations

37

F value

65.86647

Significance F

5.4707E−15

Table 2 Individual values of factors affecting labour productivity Regression coefficient

Standard error

P-value

Surface area

0.0234

0.0021

1.83E−12

Skilled labour

0.3605

0.1716

0.00345

Semiskilled labour

−0.0010

0.0003

0.00134

Gang size

−0.4138

0.1295

0.00256

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Graph 1 Line fit plot of surface area

Graph 2 Line fit plot for skilled labour

Graph 3 Line fit plot for semiskilled labour

Graph 4 Line fit plot for gang size

tion, and thence, they prove that statistical results are sensibly agreeing and have a reliability inference.

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Graph 5 Normal probability plot for labour productivity in slab formwork

5 Conclusion • Major buildability factors influencing the labour productivity are identified and addressed namely area of formwork, skilled labour, semiskilled labour and total gang size were identified. • The outcomes of this research provide a correlation value has 92% between the independent variables. • 85% of labour productivity (dependent variable) result is explained by four independent variables namely area of formwork, skilled labour, semiskilled labour and total gang size. • This paper says there is 65% of significance for the independent variables as predictors of dependent variables. • Significance F values are too small, i.e. 5.4707E−15 very close to value 0 which says independent variable does not occur by chance. • Amongst four buildability factors identified in this research, area of formwork completed stands first in influencing the labour productivity in slab formwork followed by skilled labour, semiskilled and gang size. • In normal probability plot, most of the values fall on straight line which explains there is a linear relationship between the dependent and independent variable.

References 1. Jarkas AM (2014) Buildability factors influencing formwork labour productivity of walls. Int J Constr Manage 10 2. Jarkas AM (2011) Buildability factors that influences micro level formwork labour productivity of beams in building factors. J Constr Dev Countries 16 3. Kulkarni VS, Devalkar RV (2017) Ergonomics analysis of building construction workers using RULA and REBA techniques, vol 11. Elsevier, Amsterdam 4. de Carvalho ACV, Granja AD, da Silva VG (2017) A systematic literature review on integrative lean and sustainability synergies over a building’s lifecycle, vol 103. Elsevier, Amsterdam 5. Soumya RS, Nishara Parveen A (2017) Labour productivity model for structural elements by varying buildability factors using multiple regression. Int J Sci Eng Res 5 6. Lee D, Lim H, Kim T, Cho H, Kang K-I (2017) Advanced planning model of formwork layout for productivity improvement in high-rise building construction. Int Res J Eng Technol

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7. Li S, Wu X, Zhou Y, Liu X (2016) A study on the evaluation of implementation level of lean construction in two Chinese firms, vol 71. Elsevier, Amsterdam 8. Belayutham S, Gonzalez VA, Yiu TW (2016) Lean-based clean earthworks operation, vol 142. Elsevier, Amsterdam 9. Ko C-H, Kuo JD (2015) Making formwork construction lean. J Civ Eng Manage 21 10. Boopathi G, Kalidindi SN (2014) Impact of equipment usage on labour productivity in The Indian Construction Industry at the activity level, Apr 2014 11. Youssouf A, Rachid C, Verzea I (2014) Contribution to the optimization of strategy of maintenance by lean six sigma, vol 55, Aug 2014 12. Ahmed MT, Zakaria R, Mohamad R, Ismail MA (2014) Benchmarks for sustainable formwork system. In: International conference on sustainable infrastructure and built environment in developing countries, vol 63, June 2014 13. Zin RM, Ismail MA, Alashwal MA, Hassin S (2013) Sustainability elements of IBS formworks system in Malaysia, vol 174, May 2013 14. Al-Zwainy FMS, Abdulmajeed MH, Aljumaily HSM (2013) Using multivariable linear regression technique for modeling productivity construction in Iraq, July 2013 15. Ahmed MT, Zakaria R, Mohamad R, Ismail MA (2012) Importance of sustainable concrete formwork system. Adv Mater Res 598 16. Vieira AR, Cachadinha N (2011) Lean construction and sustainability-complementary paradigms (a case study), July 2011 17. Jarkas AM (2010) Analysis and measurement of buildability factors affecting edge formwork on labour productivity. Eng Sci Technol Rev 142 18. Jarkas AM (2010) Buildability factors influencing formwork labour productivity of isolated foundations. J Eng Design Technol 8 19. Jarkas AM (2010) Buildability factors affecting formwork labour productivity of building floors. Aust J Constr Econ Build 37 20. Huang R-Y, Chen J-J, Sun K-S (2004) Planning gang formwork operations for building construction using simulations, vol 13. Elsevier, Amsterdam

Performance Evaluation of Deep Beams Using Self-compacting Concrete Subjected to Corrosion R. Manjunath, Mattur C. Narasimhan, and C. Bibesh Nambiar

Abstract Effect of corrosion on RCC–SCC deep beams subjected to three different percentages of corrosion have been investigated in the present study. These SCC mixes were designed for obtaining a cube strength of M-30 grade using river sand as finer portions of the aggregate and 12.5 mm downsize jelly as coarse aggregate. Design of SCC reinforced concrete deep beams was carried out as per IS-456:2000 and the accelerated corrosion technique has been employed for carrying out the corrosion. All the trial SCC mixes were subjected to different flow ability tests in order to evaluate their SCC property as per the EFNARC guidelines. From the obtained test results, it can be observed that for the lower percentage of corrosion decrease in ultimate flexural strength was observed due to decrease in arch action. Further with increase in percentage of corrosion showed an increased ultimate flexural strength due to increase in arch action. Keywords Deep beams · Self-compacting concrete · Corrosion · Faraday’s law · Ultimate flexural strength

1 Introduction In order to achieve a very good durable structure, well designed and executed RCC has to be carried out in a systematic manner. The embedded steel is usually protected from corrosion due to the higher alkalinity of the pore solution present inside the concrete, proving a suitable and ideal environment for embedded steel bars. In this entire process, a layer of densified iron oxide film is formed on the surface of the R. Manjunath (B) Assistant Professor, Department of Civil Engineering, BMS College of Engineering, Bangalore 560019, India e-mail: [email protected] M. C. Narasimhan · C. Bibesh Nambiar Department of Civil Engineering, National Institute of Technology Karnataka, Surathkal, Mangalore 475025, India e-mail: [email protected] © Springer Nature Singapore Pte Ltd. 2021 M. C. Narasimhan et al. (eds.), Trends in Civil Engineering and Challenges for Sustainability, Lecture Notes in Civil Engineering 99, https://doi.org/10.1007/978-981-15-6828-2_9

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rebars which is usually termed as passive layers. This layer reduces the movement of ions between the rebars and concrete covered over the rebars, thus decreasing the loss caused due to corrosion [1]. However, corrosion is one of the greatest challenges and is also one of the leading distresses causing the deterioration of RCC elements [2]. Damages caused due to corrosion on the rebars as well as prestressed steel bars have been prime cause for the failure of large number of structures over the past several centuries. Thus has led to more cost towards the repairs and rehabitalation of RCC elements [3]. The entry of CO2 from the atmosphere into the concrete decreases the alkalinity of the pore solution and also the presence of chloride ions at the rebars causes the local depassivation of thin film covered on the reinforcements are the major causes for the initiation of corrosion [4]. Further larger number of chloride ions get accumulated at the rebars exceeding a particular limit called as critical chloride content [5]. This leads to the breaking down of the passive layer leading to a process called as pitting corrosion [6] making a larger number of H2 O and oxygen ions present on the top of the rebars. This causes a serious loss and hence decrease in the thickness of steel bars with the surrounding regions being unaffected.

2 Research Objectives Reinforced SCC deep beams were subjected to different percentages of corrosion namely 0%, 5% and 10% and their performances were evaluated in the present investigation. Further, the structural behaviour of these beams without and with corrosion was also evaluated.

3 Materials 3.1 Binders OPC-43 grade conforming to IS: 8112:1989 and Class F-Fly-ash procured from Udupi Thermal power plant were used as the major binders in the present research. The specific gravity of OPC-43 grade and fly-ash were 3.11 and 2.2, respectively, and their Blaine’s fineness being 340 and 370 m2 /kg.

3.2 Aggregates Naturally available river sand was used as fine aggregate, and 12.5 mm downsize jelly was used as the coarse aggregate fraction in all these reinforced deep beam concrete mixes in the present study. The specific gravity of fine aggregate and coarse

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Fig. 1 Reinforcement of beam used in the study

aggregate were 2.60 and 2.62. Both the fine aggregates and coarse aggregates used in the present study conform to the specifications of IS: 383-1970 based on the results obtained from sieve analysis.

3.3 Water For the preparation of concrete mixes, laboratory available tap water was used in the present study.

3.4 Reinforcing Steel Fe-415 grade (TMT) rebar of 8 mm diameter was used as the longitudinal reinforcement, and 6 mm dia bars were used as horizontal and vertical stirrups for the preparation of reinforcement cage in order to study the effect of reinforcement corrosion as shown in Fig. 1.

3.5 Admixture To improve the flow ability properties of all the SCC trial mixes, Master Glenium Ace 30 procured from BASF was used in the present investigation.

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4 Mixture Proportions, Preparation and Casting 4.1 Proportioning, Preparation and Casting of Specimens OPC along with fly-ash as the major binder with 580 kg/m3 with 65% of total binder content being OPC and the remaining 35% being fly-ash were used for the production of ten RCC deep beams made of SCC. These mixes were developed with constant water to binder ratio of 0.33. The details of the quantities for all the concrete mixtures are as shown in Table 1. Required number of test specimens were cast and tested, for all the ten reinforced deep beam SCC mixes. Due to the non-availability of any standard code for the design of SCC mixes, all the trial mixes were carried out based on the absolute volume method. A constant ratio of 60:40 was maintained in all the mixes in case of FA: CA. Ribbon type mixer was used for mixing of all the ingredients in order to provide better mixing. The fine and coarse were initially poured into the mixer and dry-mixed for two minutes. Then, binder materials were then added to the mixer and rotated for about one more minute. The remaining quantity of water was added along with superplasticisers and mixed thoroughly to get a homogeneous concrete mix. Slump flow, V-funnel and the L-box tests were carried out in order to evaluate their flow ability properties and to check their suitability for SCC mixes. The deep beams were cast with the size of mould being 600 mm × 150mm × 350mm. Cube specimens were cast using moulds of size 150 mm × 150 mm × 150 mm for evaluating the compressive strength. The cubes were demoulded immediately after 24 h of casting and were kept in a tank filled with water under ambient laboratory conditions. Required a number of specimens were cast for determining compressive strengths at 7 and 28-days. In each case, the average of results for three test specimens was considered for strength evaluations. Table 1 Quantities of materials for SCC mixes in kg/m3

Ingredients

Quantities

Cement

377

Fly-ash

203

Fine aggregate

871

Coarse aggregate

739

Water

191.4

Superplasticiser

4.64

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4.2 Accelerated Corrosion Technique Using an electric current of constant magnitude to the embedded rebars, accelerated corrosion tests can be conducted. After curing, deep beam specimens were subjected to desired corrosion levels, i.e. 5%, and 10%. In order to initiate the rebars corrosion present inside the beam, specimen’s phenomena of electrochemical corrosion technique was adopted. To accelerate, the process of corrosion direct current was applied on the rebar-mesh embedded inside the concrete specimen using an integrated system, incorporating a direct power supply with an output of 64 V and 10 Amps to monitor the current. Test set-up consists of a full ground-level tank of 5% NaCl solution in which beam specimens was almost fully immersed of their height as shown in Fig. 2. According to the percentage of corrosion required, the time of application is calculated with a constant current of 1.4 Amps using Eq. 1. Similarly, the time required for obtaining the required percentage of corrosion is calculated and tabulated as shown in Table 2. For the corrosion process, to occur both moisture and oxygen are very much essential. The flow of current inside the steel reinforcement inside the beam specimens was considered as anode. The cathode is simulated by means of providing a separate stainless steel plate which was placed along the beam length. A schematic representation of the test set-up is shown in Fig. 2. Amount of current to be applied to obtain the required degree of corrosion can be calculated using Faraday’s law (Eq. 1). Icorrosion =

ρ × Wi × F 100 × W × t

(1)

Fig. 2 Plan view of the corrosion tank

Table 2 Amount of time required to induce specified corrosion levels in deep beam specimens

Current (Amps)

Degree of corrosion (%)

Time required (days)

1.4

5

4.56

10

9.12

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ρ Wi F W t

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Percentage loss of weight expressed in terms of degree of induced corrosion Initial weight of steel (= 3196 g-measured) Faraday’s constant = 96,487 Amp-sec Equivalent weight of iron (= 27.925 g) Time in days.

4.3 Testing Procedure The specimens to be tested were placed on the test bed on the UTM of 200 ton capacity. The beam specimens of both non-corroded and corroded, three of each sets, were tested under two-point loading condition. White washing was done for all the deep beams in the front faces in order to clearly observe the crack initiation and propagation along with the loading and support points being marked on the beam. The beams were placed with the help of those markings and dial gauges were fixed to find deflections at both the support and the midspan. Gradually, loading was done with increments of one tonne, deflection at support and midspan was measured. The load corresponding to first crack of the beam was noted down. Propagation of existing cracks and initiation of any new crack were observed till the deep beam reaches its ultimate load. Vertical deflection measurements are made at both midspan and at support since loading is done by using UTM. Two dial gauges are connected at midspan and support as shown in Fig. 3. Fig. 3 Front view of vertical deflection arrangements

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Table 3 Flow ability and compressive strength of SCC deep beam mixes Mix ID

Slump flow mm

Slump flow T5oo mm

L-box blocking V-funnel sec ratio

Compressive strength MPa 7D

28D

DB1 -S1

660

5

0.85

10

22.

31.5

DB1 -S2

675

3

0.90

9

24

33.5

DB1 -S3

650

6

0.85

11

24

34

DB2 -S1

660

5

0.88

10

26

37

DB2 -S2

680

4

0.90

8

22

32

DB2 -S3

675

4

0.85

10

27

39

DB3 -S1

690

3

0.91

8

24

38

DB3 -S2

685

4

0.86

11

27

37

DB3 -S3

670

3

0.86

10

25

39

DB1 , DB2, DB3 —Deep beam 0% corrosion, 5% corrosion, 10% corrosion

5 Results and Discussion 5.1 Flowability and Compressive Strength of SCC Mixes Slump flow, V-funnel and L- box tests generally prescribed for flowable mixes were performed on all the SCC mixes as per relevant EFNARC guidelines and the compressive strength were tested as per IS: 516:1959. The slump flow tests were carried out using the slump cone in order to check the filling ability of the concrete mixes. The developed SCC mixes satisfied all the properties as per the EFNARC guidelines are shown in Table 3, with their compressive strength in the range of 27–39 MPa at the age of 7 and 28 days as shown in Table 3. Deep beams with 0, 5 and 10 percentage corrosion applied with the help of accelerated corrosion technique were tested in UTM with two-point loading arrangements. The results obtained are shown in Table 4. Effective length of deep beam is 450 mm with a shear span of 150 mm which incorporates one-third loading. Shear span/depth ratio are of value 0.43 indicates the failure should be diagonal compression. The variation in the strength parameter is different from slender beams. With 5% of corrosion, the ultimate load carrying capacity of deep beams decreases from 32.67 to 24.67 ton. The deduction in ultimate capacity is due to slip between concrete and reinforcement which reduces the bond strength. But in case of 10% corrosion, the ultimate strength increases to a value of 30.33. This increase in strength is due to the change in failure mechanism. For normal deep beam strut action is predominant compared to arch action but by increasing the percentage in corrosion to 10% slip between the concrete and steel may change from beam action to arch action which may increase the strength.

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Table 4 Ultimate load carrying capacity of beams Mix ID DB1 -S1

Corrosion (%) 0

First crack load (t)

Avg. first crack load (t)

Failure load (t)

Ultimate load (t)

25

25.67

31

32.67

DB1 -S2

26

33

DB1 -S3

26

34

DB2 -S1

5

20

21.33

25

DB2 -S2

23

24

DB2 -S3

21

25

DB3 -S1

10

27

25.67

31

DB3 -S2

25

30

DB3 -S3

25

30

24.67

30.33

Load deflection behaviour of deep beam specimens having 0, 5 and 10% corrosion was plotted as shown in Figs. 4, 5 and 6. Maximum deflection was observed for 0% corrosion when compared to 5 and 10%. This may be due to higher load carrying capacity of 10% corrosion beam, due to arch action. Moment curvature behaviour Fig. 4 Load-deflection graph of beams for 0% corrosion

Fig. 5 Load-deflection graph of beams for 5% corrosion

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Fig. 6 Load-deflection graph of beams for 10% corrosion

was observed as shown in Figs. 7, 8 and 9 for all deep beams which showed similar behaviour for both 0 and 10%, but with a lesser values of curvatures for 5% corrosion as compared to other percentages. Shear cracks are obtained between loading point and support in all the cases as shown in Figs. 10, 11 and 12. The failure was all due to shear and failure of beam was occurred due to crushing of concrete. After initial cracking, stirrup is helping to decrease the crack propagation between loading point and support. The concrete without stirrup failed within small load after first crack, but an increase in the load of seven ton was observed with the help of stirrups for uncorroded beams. Further, for 5 and 10% corrosion being 3.34 ton and 4.66 ton, respectively. Fig. 7 Moment-curvature graph of beams—0% corrosion

Fig. 8 Moment-curvature graph of beams—5% corrosion

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Fig. 9 Moment-curvature graph of beams—10% corrosion

Fig. 10 Crack pattern of deep beam—0% corrosion

Fig. 11 Crack pattern of deep beam—5% corrosion

The reduction in these values is due to decrease in the bond strength between steel reinforcement and concrete and the reduction in mass of steel reinforcement.

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Fig. 12 Crack pattern of deep beam—10% corrosion

6 Conclusions From the obtained results, it can be concluded that the reduction in ultimate strength was obtained for 5% corrosion; however, increase in the ultimate flexural strength was obtained for 10% of corrosion due to the arch action. Further, in case of ultimate strength, deep beams with 5% corrosion are having less deflection values compared to 0 and 10% corrosion. This may be attributed to the reduction in the ultimate load carrying capacity of the deep beams tested herein. Diagonal compression failure was observed due to crushing of concrete and the crack propagation started from loading point to the support. Prior to flexural crack, diagonal cracks occur prior before the failure of beam.

References 1. Tuutti K (1982) Corrosion of steel in concrete, CBI Report 4:82, The Swedish Cement and Concrete Institute, p 468 2. Broomfield J (2002) Corrosion of steel in concrete: understanding, investigation and repair, 2nd edn. Taylor & Francis, Abingdon, United Kingdom 3. Bertolini L, Elsener B, Pedeferri P, Polder R (2004) Corrosion of steel in concrete, prevention, diagnosis. Repair. Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, Germany 4. Montemor M, Simões A, Ferreira M (2003) Chloride-induced corrosion on reinforcing steel: from the fundamentals to the monitoring techniques. Cem Concr Compos 25(4–5):491–502 5. Angst UM, Elsener B, Larsen CK, Vennesland O (2011) Chloride induced reinforcement corrosion: electrochemical monitoring of initiation stage and chloride threshold values. Corros Sci 53(4):1451–1464 6. Stansbury E, Buchanan R (2000) Fundamentals of electrochemical corrosion. ASM International, Ohio, USA

Performance Evaluation of Steel Fiber-Reinforced Deep Beams Using Self-compacting Concrete R. Manjunath, Mattur C. Narasimhan, and Janagam

Abstract Reinforced self-compacting deep beams were developed, and their performance with varying percentages of steel fibers has been investigated in the present research. Fine aggregate being river sand along with 12.5 mm downsize jelly as coarse aggregate, and all the concrete mixes were proportioned for attaining a strength of M-30 grade concrete. Based on standard code IS: 456-2000, all the reinforced SCC deep beams were designed. As per the EFNARC guidelines, all the SCC mixes were subjected to different flowability tests for ascertaining the concrete as SCC mixes. Test results concluded that the ultimate flexural strength of the reinforced concrete deep beams increased with the increase in the percentage of steel fibers due to the better stitching actions of the steel fibers with the cementitious matrix. Keywords Reinforced deep beams · Self-compacting concrete · Steel fibers · Ultimate flexural strength

1 Introduction Self-compacting concrete has gained more attention from the past few decades as an excellent material for concrete constructions due to its capability for passing through congested reinforcements and consolidating under its own weights. Usage of SCC reduces the number of skilled labor required for better handling and surface finish for the concrete. This decreases the time and the overall cost of construction when compared to normal vibrated concrete [1]. R. Manjunath (B) Assistant Professor, Department of Civil Engineering, BMS College of Engineering, Bangalore, Karnataka 560019, India e-mail: [email protected] M. C. Narasimhan · Janagam Department of Civil Engineering, National Institute of Technology Karnataka, Surathkal, Mangalore, Karnataka 575025, India e-mail: [email protected] © Springer Nature Singapore Pte Ltd. 2021 M. C. Narasimhan et al. (eds.), Trends in Civil Engineering and Challenges for Sustainability, Lecture Notes in Civil Engineering 99, https://doi.org/10.1007/978-981-15-6828-2_10

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The effect of different span to depth ratio between 1 and 3 and shear span-todepth ratio varying from 0.23 to 0.7 was studied on thirty-five SS concrete beams in the present investigation. Further, the deflection, crack width, crack pattern, failure modes, and ultimate load in shear have also been studied for beams having seven different types of web reinforcements. It can be observed that S/D ratio and SS/D ratios affect the performance of the various types of web reinforcement. Web reinforcement in the horizontal direction with closely spaced at the bottom found to be more effective for low S/D ratio and SS/D ratio. Diagonal cracking was found to be the major cause for the failure [2]. Beams of dimensions 100 × 330 × 1050 mm with reinforced SCC mixes were tested under two-point loading arrangements. The SS to EDR (a/d), strength of the concrete, and ratios of web reinforcement in vertical direction were considered as the major parameters. Reduced cracking and max shear strength were observed by an average value of 28.6 and 23.3% with the increase in a/d ratio from 0.6 to 1.0. Increased cracking along with enhanced shear strength having a value of 11.7 and 38.8% has obtained with the increase in compressive strength. The increase in the vertical web reinforcement ratio from 0.25 to 0.57% showed an increase in the ultimate shear strength by average ratio of 10.1%. Using the analytical results, a new model has been designed for predicting the ultimate shear strength of SCC deep beams depending on modified strut and tie model with the adoption of a circular failure interaction relation. Higher correlation was observed from the obtained relation when compared to ACI-2011 Code method [3]. Standard compression tests were conducted on concrete cylinders in order to investigate the compression behavior of SFRC. These cylinders consisted of different steel fibers. The peak strain curve along with stress–strain graphs for the cylindrical specimens and the volumetric effect ratio of steel fibers on compressive strength were also exploited. Increase in the fibers contents increased the compressive strain of the cylindrical specimen as obtained from the results. Addition of steel fibers caused an increase in the strength corresponding to peak stress [4]. In order to provide better applicability and its performances in case of SFRC, dispersion of fibers plays a major role in attaining these characteristics. Especially, SCC provides more advantages in better dispersion of steel fibers which is very critical for wider application as a structural fiber-reinforced concrete. A model was proposed which includes the optimization of fibers in the entire skeleton through the concept of equivalent specific surface diameter” [5]. Twelve SS beams were tested up to failure under four-point loading in order to study the shear behavior of fiber-reinforced self-compacted concrete (FRSCC) deep beams. The steel fibers ratios (0.0, 0.50, 0.75, and 1.00%) and the effective shear span to depth ratio; a/d that varied from 0.6 to 1.0 were considered as the major factors in the present investigation. Also, the main flexure reinforcement ratio was variable (1.0, 1.60, and 2.20%). Further, the effect of vertical and horizontal web reinforcement was also investigated. Addition of steel fibers enhanced the cracking load, ultimate capacity, displacement, and energy absorption of all the tested FRSCC deep beams. Maximum performance was observed with deep beams having a steel fibers content of 1% with the increase in the ultimate flexural capacity by 40% [6].

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2 Research Objectives Flexural performance of different percentages of steel fibers namely 0.75 and 1.5% w.r.t to total volume of concrete on the reinforced concrete deep beams made of self-compacting concrete mixes was studied in the present investigation.

3 Materials 3.1 Binders The major binders used in the present investigation were OPC-43 grade conforming to IS: 8112:1989 and Class F-Fly ash procured from Udupi thermal power plant. The specific gravities of these binders were, respectively, 3.11 and 2.6 with their Blaine’s fineness being 340 and 370 m2 /kg.

3.2 Aggregates River sand was used as fine aggregate, and 12.5 mm downsize granite chips were used as the coarse aggregate fraction in all these reinforced deep beam concrete mixes. River sand had a specific gravity 2.60, and jelly had a specific gravity of 2.62. The results of sieve analysis of river sand used in the present study conform to the specifications of IS: 383- 1970 as shown in Table 1. Table 1 Sieve analysis results of fine aggregates

IS sieve

% Passing

Grading requirement as IS 383-1970

10 mm

0

100

4.75 mm

99.6

90–100

2.36 mm

97.8

75–100

1.18 mm

82.4

55–90

600 µn

36.8

35–59

300 µn

5.1

8–30

150 µn

0.6

0–10

Zone II

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Fig. 1 Reinforcement of beam used in the study

3.3 Water The laboratory available tap water was used for the preparation of all the concrete mixes.

3.4 Reinforcing Steel Fe-415 grade of thermo-mechanically treated rebar of 8 mm diameter was used as the longitudinal reinforcement, and 6 mm diameter bars were used as horizontal and vertical stirrups for the reinforcement cage as shown in Fig. 1.

3.5 Steel Fibers The physical properties of helix steel fibers used in the present study are shown in Table 2 and Fig. 2. Table 2 Steel fibers—physical properties

Properties

Value

Length

25 mm

Diameter

0.5 mm

Aspect ratio

50

Tensile strength

2465 MPa

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Fig. 2 Helix steel fiber used in the study

3.6 Admixture High range water reducing admixture named—MasterGlenium Ace 30 procured from BASF—is used for enhancing the flowability properties of all the concrete mixes prepared herein.

4 Mixture Proportions, Preparation, and Casting 4.1 Proportioning, Preparation, and Casting of Specimens Nine reinforced SCC deep beams were developed with OPC and fly ash as the major binder with 580 kg/m3 with 65% of total binder content being OPC and the remaining 35% being fly ash. A constant w/b ratio of 0.33 was maintained for all the mixes. The details of the mix proportions of the various concrete mixtures are as shown in Table 3. Table 3 Details of trial concrete mixes quantities in kg/m3

Ingredients

Quantities

Cement

377

Fly ash

203

Fine aggregate

871

Coarse aggregate

739

Water

191.4

Superplasticizer

4.64

Steel fibers—0.75%

1.79

Steel fibers—1.5%

3.58

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Using SCC mixes specimens were cast and tested for all the reinforced concrete deep beam. Absolute volume method was incorporated for proportioning of all the quantities for SCC mixes due to the non-availability of the national code for mix design. The fine aggregates were taken as 60% and the coarse aggregates being 40% to coarse aggregates for the proportioning of the concrete mixes. In order to ensure better mixing of all the materials, ribbon-type mixer was used. Initially, the river sand and jelly were poured into the mixer and dry-mixed for two minutes. Then OPC and fly-ash were added to the mixer and rotated for about one more minute. Then the remaining water mixed with admixture was added, and further mixed till a homogeneous concrete mix was obtained. Different flowability tests such as slump flow, V- Funnel, and the L-box tests were carried out on all the concrete mixes for ascertaining whether these mixes fall under the category of SCC mixes. The deep beams were cast with the size of mold being 600 mm × 150 mm × 350 mm. Compressive strength of all the mixes was evaluated using the cube specimens of size 15 cm × 15 cm × 15 cm. After 24 h of casting, all the specimens were demolded and allowed for water curing under ambient laboratory conditions. Sufficient numbers of specimens were cast for determining compressive strengths at 7 and 28 days. In each case, the average of results for three test specimens was considered for strength evaluations.

4.2 Testing Procedure Specimens were placed on the test bed made on UTM of 200-ton capacity. Beam specimens cast with three different percentages of steel fibers, and three of each set were tested under two-point loading condition as shown in Fig. 3. In order to have a better visibility of the cracks and observe the initiation and propagation of cracks, the front faces of the deep beam specimens were whitewashed. Further, the loading and support points were also marked on the beam specimens. The beams were placed with the help of those markings, and dial gauges were fixed to find deflections at both the support and the midspan. Loading was done gradually and for an increase of 1 ton, deflection at support and midspan were measured. The load corresponding to first crack of the beam was noted down. Propagation of existing cracks and initiation of any new crack were observed till the deep beam reaches its ultimate load. Vertical deflection measurements are made at both midspan and at support since loading is done by using UTM. Two dial gauges are connected at midspan and support as shown in Fig. 4.

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Fig. 3 Front view of the deep beam subjected to loading

Fig. 4 Modes of arrangements of vertical deflections

5 Results and Discussion 5.1 Flowability and Compressive Strength of SCC Mixes Flowability tests such as slump flow, V-funnel, and L-box generally prescribed for flowable mixes were performed on the SCC mixes as per relevant EFNARC guidelines, and the compressive strength was tested as per IS: 516:1959. The slump flow tests were carried out using Abram’s cone, to evaluate the filling ability of the concrete mixes. The developed SCC mix satisfied all the properties as per the EFNARC guidelines as shown in Table 3, with their compressive strength in the range of 26–39 MPa at the age of 7 and 28 days as shown in Table 4.

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Table 4 Flowability and compressive strength of SCC Specimen

Slump flow mm

L-Box blocking ratio

V-Funnel sec

Compressive Strength MPa 7D

28D

DB-0

665

0.85

11

29

36

DB-0.75

655

0.87

10

28

34

DB-1.5

650

0.86

12

26

39

Table 5 Ultimate load-carrying capacity of SCC deep beams with steel fibers Sp. No

Steel fiber (%)

First crack load (t)

Avg. First crack load (t)

Failure load (t)

Ultimate load (t)

DB S1

0

25

25.67

31

32.67

DB-S2

26

33

DB-S3

26

34

DB-S1

0.75

33

32.6

43

DB-S2

32

40

DB-S3

33

43

DB-S1

1.5

43

41.3

50

DB-S2

41

48

DB-S3

40

46

42.3

48.0

Deep beams with different percentage of steel fibers were tested in UTM with two-point loading setup as shown in Figs. 2 and 3. The results obtained are shown in Table 5. Effective length of deep beam is 450 mm with a shear span of 150 mm which incorporates one-third loading. Shear span/depth ratio are of value 0.43 indicates the failure should be diagonal compression. The strength of deep beams will vary up to 2–3 times from ordinary beams. The primary failure criteria are shear rather than flexure. Load deflection was plotted for deep with different percentage of fibers shown in Figs. 5, 6 and 7. Increase in the percentage of steel showed an increase in the first crack load as well as the ultimate load at failure. This behavior may be due to the uniform distribution of steel fibers inside the matrix causing a better switching of the cracks at the plane of crack initiations compared to beams without fibers. Max deflection occurred in case of deep beam with 1.5% of steel fibers. Further, moment-curvature graphs for different percentages of steel fibers are as shown in Fig. 8. The curve for different specimens of each individual did not show any major deviations. Max curvature is obtained in case of deep beam with 1.5% of steel fiber. Shear cracks are obtained between loading point and support in all the cases as shown in Figs. 9, 10 and 11. After initial cracking, the availability of steel fibers provided bridging actions decreasing the propagation of cracks. There were almost

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Fig. 5 Load-deflection graph of SCC deep beams with 0% steel fibers

Fig. 6 Load-deflection graph of SCC deep beams with 0.75% steel fibers

Fig. 7 Load-deflection graph of SCC deep beams with 1.5% steel fibers

no flexural cracks observed. Further, failure was due to diagonal compression, i.e., from the loading point to the support diagonal cracks.

6 Conclusions There was no significant variation in failure loads and crack pattern. Increase in the ultimate load-carrying capacity by about 12.45% was obtained for 0.75% steel fiber content. Further increase in the percentage to 1.5% steel fiber, increase in the failure

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Fig. 8 Moment-curvature graphs with different percentages of steel fibers

Fig. 9 Crack pattern of deep beam—0% steel fibers

Fig. 10 Crack pattern of deep beam—0.75% steel fibers

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Fig. 11 Crack pattern of deep beam—1.5% steel fiber

loads was observed to about 32.7%. The failure observed was mainly due to diagonal compression. Further, no flexural cracks were observed.

References 1. Goodier CI (2003) Development of self-compacting concrete. Proc ICE—Struct Build 156(4):405–414 2. Kong FK, Robins PJ, Cole DF (1970) Web reinforcement effects on deep beams. ACI J 67(12):1010–1018 3. Wisam HS (2014) Shear behaviour of self compacting concrete deep beams. J Eng Dev 18(2):1813–7822 4. Dhakal RP, Wang C, Mander JB (2005) Behaviour of steel fibre reinforced concrete in compression. In: International symposium on innovation & sustainability of structures in civil engineering, At Nanjing, China 5. Ferrara L, Park YD, Shah SP (2007) A method for mix-design of fiber-reinforced self-compacting concrete. Cem Concr Res 37(6):957–971 6. Adam MA, Said M, Elrakib TM (2016) Shear performance of fiber reinforced self-compacting concrete deep beams. Int J Civil Eng Technol (IJCIET) 7(1):25–46

Seismic Analysis of Open Ground Storey Building with Different Plan Configuration and Elevation Symmetry Gireesha Bhat and Thushar S. Shetty

Abstract The configuration and symmetry of the building plays a major role under lateral loads in the building. This paper contains the study on seismic behaviour of Open Ground Storey (OGS) building with different combination of plan configuration and elevation symmetry. Further, comparative study on results obtained from response spectrum analysis is carried out. Modelling is done as per the guideline given in Indian earthquake code IS 1893:2002 and 2016 by using CYPECAD-2018 analysis software. The applicability of code provisions has been checked in this study. Keywords Open ground storey · Plan configuration · Elevation symmetry · Response spectrum method

1 Introduction Nowadays, the population increase in major cities and the development of smart cities have led to the construction of taller and bigger structures. Among these structures, the Open Ground Storey (OGS) of multi-storey building provides the space for parking of the vehicles. The recent studies on the failure of building due to the earthquake shows that the OGS buildings are found to be the weakest to resist the earthquake. The infill wall which is present in the frame will change the behaviour of the building under lateral loads. However, if plan and elevation symmetric are same, then the code IS 1893 (Part1): 2016 [1], allows the analysis of OGS RC-framed building with masonry infill G. Bhat (B) PG Student, Department of Civil Engineering, NMAM Institute of Technology, Nitte, Karkala Taluk, Udupi District, Karnataka 574110, India e-mail: [email protected] T. S. Shetty Assistant Professor, Department of Civil Engineering, NMAM Institute of Technology, Nitte, Karkala Taluk, Udupi District, Karnataka 574110, India e-mail: [email protected] © Springer Nature Singapore Pte Ltd. 2021 M. C. Narasimhan et al. (eds.), Trends in Civil Engineering and Challenges for Sustainability, Lecture Notes in Civil Engineering 99, https://doi.org/10.1007/978-981-15-6828-2_11

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wall, without reinforcement or RC structural walls. According to the code guidelines, the soft storey(s) has a lateral stiffness less than 80% in storey with infill materials and less than 90% lateral strength in soft storey(s) with infill materials. By using IS 13920:2016, the RC structural walls or shear walls for a building located in the seismic zones III, IV and V shall be designed and detailed [2]. The power full earthquake that hit the Bhuj area of Gujarat at 8:46 A.M. on 26th January, 2001 was reported as republic day earthquake which has been observed as most disinterring earthquake in last fifty years in India. The M w 7.9 (intensity) quake gave rise to a major loss of life and property. Around 20,000 people were reported dead, and another 1,67,000 were injured [3]. The approximate economic loss was calculated as |22,000 crores. Sixteen experts from IIT Khanpur made the reconnaissance survey on damages due to earthquake from 2nd to 14th February 2001 and observed various structural and geotechnical damages [4]. Many number of latterly built high rise RC-framed soft storey buildings were collapsed in Gujarat region and also in large distance towns from epi-centre, Morbi (125 km), Rajkot (150 km), Ahmedabad (300 km) and Surat (375 km). Kaushik and Sudhir studied various strengthening plans and analysed the effectiveness in reforming the performance of OGS buildings. Instead of using multiplication factor which was specified in several codes, manual method was formed for calculation of required strength in OGS columns. The code provisions were found to increase only the lateral strength and not the ductility of such buildings. Whereas some other method showed improvement in both the lateral strength and the ductility for improved seismic performance [5]. The researchers Kaushik et al. checked the applicability of multiplication factor 2.5 and studied the behaviour of the low-rise building. The analysis was carried out with framed model without considering stiffness of infill material as suggested in IS 1893-2002(Part-1). The conclusion of this work was without considering stiffness of infill material, and multiplication factor for OGS column is 1.25 instead of 2.5. But these researchers have not considered any different type of symmetry of the building [6, 8]. Aruna Rawat et al. made the research using eccentric bracings to reduce the mechanisms of soft storey effects in masonry infill RC building. Analysis was done for G+6 building located in Zone-V (IS 1893:2002) using nonlinear pushover analysis. The storey drift demand and collapse fragility curve showed that building with eccentric steel bracings had lower drift demand and very less probability of collapse [7]. In another study, the openings present in masonry infill wall in OGS building were studied by carrying out a simple performance assessment of low and midrise masonry infill RC frame with different infill configuration followed by fatigue analysis. The conclusion of this study was that practically no effect of openings that present in masonry infill walls on earthquake load behaviour (lateral loads) was observed [9]. Figure 1 shows a typical open ground storey building with “+” plan and rectangular elevation symmetry. The effect of recent earthquakes on different symmetry buildings insists to make a research on the plan symmetry of buildings. Figure 2 shows the

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Fig. 1 Typical open ground storey (OGS) building

Fig. 2 Failure of typical open ground storey building with rectangular plan and elevation symmetry

failure pattern of rectangular plan and rectangular elevation symmetry building which was collapsed during Bhuj earthquake in 2001. Along with infill wall, the positioning of columns or symmetry of columns also plays a major role under lateral loads that may be wind load or earthquake load. Hence, this research work also contains the study on the different symmetry of columns.

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2 Objectives The purpose of this research work is as follows; • To know the role of plan and elevation symmetry in the seismic analysis of OGS buildings. • To study the behaviour of OGS building with different combinations of plan and elevation symmetry under the lateral loads. • To verify the applicability of multiplication factor given in IS1893:2002 for the design of OGS building for different plan symmetry conditions.

3 Methodology For the comparative study on the OGS building model, the following steps are followed: 1. Selection of various buildings with different plan symmetry. 2. Study on existing literature for OGS building column positioning with different symmetry. 3. The OGS model was developed for triangular, rectangular, pentagonal, hexagonal and circular plan with masonry infill in upper stories. 4. Response spectrum method was carried out using CYPECAD-18 analysis software. 5. Comparison of various results. As per clause 6.4.2 of IS 1893:2002, analysis of response spectrum was performed. During dynamic analysis, calculated base shear was compared with a base shear calculated using a fundamental period Ta, where Ta is specified in Clause 7.6. If calculated base shear from response spectrum method (VB− ) is less than base shear calculated from equivalent static load method (B V, i.e. usingTa as per Clause 7.6), then all the response quantities shall be multiplied by ratio VB− /VB as per Clause 7.8.2. The building model considered for this study is not an existing building. General G+10 floor OGS framed building, located in seismic zone V, is considered for modelling. The buildings modelled for different configuration of plan are triangular, rectangular or plus, pentagonal, hexagonal and circular in plan symmetry and rectangular in elevation symmetry. These buildings are having equal number of columns in all type of plan symmetry, and masses in each floor are almost the same. The Open Ground Storey (OGS) provides parking for vehicles for above flat’s owners.

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The height of OGS is taken as 3.5 m, and height of other storeys as 3.05 m. The total height of the building is 35.2 m and is made up of reinforced concrete (RC) and ordinary moment resistance frame (OMRF). The thickness of slab is taken as 125 mm at each floor level, and the thickness of external and internal masonry infill wall is 230 mm. The rectangular columns of size 300 × 725 mm are considered and that of circular columns of diameter 600 mm are considered. The size of beams taken is 300 × 525 mm, 300 × 450 mm and 200 × 450 mm. The design considerations taken in this work are as follows: The live load for the structure is taken as 2 kN/m2 . The grade of steel and concrete are assumed as Fe500 and M25 , respectively. The considered seismic zone is zone-V, and corresponding zone factor is 0.36. The response reduction factor is 5, and the (SMRF) and importance factor is 1.0. The damping of structure is assumed as 5% type II of soil is considered during modelling. In this study, the bare frame elements with and without infill were modelled using CYPECAD-2018 analysis software. Analysis is carried out using response spectrum method. The load combinations for this work are considered as per the IS 1893:2016 which are as follows. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12.

0.9 DL + 1.5 (ELx + 0.3Ely + 0.3ELz) 0.9 DL + 1.5 (ELy + 0.3Elx + 0.3ELz) 0.9 DL − 1.5 (ELx + 0.3Ely + 0.3ELz) 0.9 DL − 1.5 (ELy + 00.3Elx + 00.3ELz) 1.2 (DL + LL − (ELx + 0.3Ely + 0.3ELz)) 1.2 (DL + LL − (ELy + 0.3Elx + 0.3ELz)) 1.2 (DL + LL + (ELx + 0.3Ely + 0.3ELz)) 1.2 (DL + LL + (ELy + 0.3Elx + 0.3ELz)) 1.5 (DL − (ELx + 0.3Ely + 0.3ELz)) 1.5 (DL − (ELy + 0.3Elx + 0.3ELz)) 1.5 (DL + (ELx + 0.3Ely + 0.3ELz)) 1.5 (DL + (ELy + 0.3Elx + 0.3ELz)).

The following types of general building models with different configuration of plan are considered for comparison. 1. 2. 3. 4. 5.

Triangular plan symmetry Rectangular plan symmetry Pentagonal plan symmetry Hexagonal plan symmetry Circular plan symmetry.

Figures 3, 4, 5, 6 and 7 shows the different symmetry of plans, and Fig. 8 shows the column orientation of different plans.

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Fig. 3 Typical upper floor plan of triangular plan symmetry

4 Results and Discussions The building of triangular plan with rectangular elevation symmetry consists of six numbers of 2BHK flats in each floor. The typical building model is as shown in Fig. 9. The rectangular columns are positioned with an angle of 0°, 60° and 120° with x-axis. In the building model with triangular positioning of columns, the deflection observed in open ground floor frame was 114.44 mm. The deflection pattern of the model is as shown in Fig. 10. By comparing the deflections with other buildings, the deflection of triangular plan building was found to be minimum. The building with rectangular or “+” type plan with rectangular elevation symmetry consists of four numbers of 3BHK flats in each floor. The typical building model is as shown in Fig. 11. The rectangular columns are positioned with an angle of 0° and 90° with x-axis. In the building model with rectangular or “+” type positioning of columns, the deflection observed in open ground floor frame was 122.12 mm which

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Fig. 4 Typical upper floor plan of rectangular plan symmetry

was slightly more than the deflection of building with triangular plan symmetry. Figure 12 shows deflection for the above model. The building with pentagonal plan with rectangular elevation symmetry consists of five numbers of single BHK flats in each floor. The typical building model is as shown in Fig. 13. The rectangular columns are positioned with an angle of 0°, 72°, 144°, 216° and 288° with x-axis. In the building model with pentagonal type positioning of columns, the deflection observed in open ground floor frame was 129.64 mm which is slightly more than the building with rectangular plan symmetry The deflection pattern of the above model is as shown in Fig. 14. The building with hexagonal plan with rectangular elevation symmetry consists of six numbers of single BHK flats in each floor. The typical building model is as

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Fig. 5 Typical upper floor plan of pentagonal plan symmetry

shown in Fig. 15. The rectangular columns are positioned with an angle of 0°, 60°, 120°, 240° and 300° with x-axis. In the building with hexagonal type positioning of columns, the deflection observed in open ground floor frame was 134.62 mm which is more than the deflection of pentagonal plan symmetry building. The deflection pattern of the above model is as shown in Fig. 16. The building with circular plan with rectangular elevation symmetry consists of five numbers of single BHK flats in each floor. The typical building model is as shown in Fig. 17. The circular columns are positioned so as to form a circle. For the circular type positioning of columns, the deflection in open ground floor frame was found to be 137.02 mm, which is the maximum deflection obtained, during all the different building models considered in present research work. Figure 18 shows the deflection pattern for the above model.

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Fig. 6 Typical upper floor plan of hexagonal plan symmetry

The graph of modification factor v/s roof deflection is plotted for different plan symmetry as shown in Fig. 19. As the modification factor increases, the roof deflection goes on decreasing, which means structure became stronger. Variation in deflection of different plan configuration patterns is shown in Fig. 20. As the number of sides increases, variation of deflection is also increasing. For lateral loads, ten modes in both X- and Y-directions were given. The maximum response observed was in seismic mode X 1 for all type of symmetry models. The corresponding modification factors and maximum roof displacement are tabulated as shown in Table 1.

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Fig. 7 Typical upper floor plan of circular plan symmetry

5 Conclusion and Recommendation • From this research work, it has been found that in the earthquake analysis of a structure with infill walls, the symmetry of the columns also resists some lateral loads. • Modification factor for open ground storey building with different plan symmetry is 2.25 instead of 2.5 as specified in IS 1893: 2002. • As the number of sides in a structure increased, the plan symmetry became circular, and the modification factor reduced to 1.4 instead of 2.5. • Thus, to reduce the open ground storey effect, different plan symmetry with maximum number of sides can be recommended.

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132 Fig. 9 Building model of triangular plan and rectangular elevation symmetry

Fig. 10 Deflection pattern for triangular plan building

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Fig. 12 Deflection pattern for rectangular plan building

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134 Fig. 13 Model of pentagonal plan and rectangular elevation symmetry

Fig. 14 Deflection pattern for pentagonal plan building

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Fig. 16 Deflection pattern for hexagonal plan building

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136 Fig. 17 Model of circular plan and rectangular elevation symmetry

Fig. 18 Deflection pattern for circular plan building

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Fig. 19 Graph showing modification factor V/S roof displacement

Fig. 20 Graph showing variation in deflection of different plan configuration patterns Table 1 Modification factor and maximum roof displacement

Plan

Earthquake load case

Modification factor

Maximum roof displacement

Triangular

Seismic X1

2.24

114.44

Rectangular

Seismic X1

1.73

122.12

Pentagonal

Seismic X1

1.55

129.64

Hexagonal

Seismic X1

1.45

134.62

Circular

Seismic X1

1.41

137.61

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References 1. Bureau of Indian Standards (2002) IS 1893 (Part 1): 2016 Indian standard criteria for earthquake resistant design of structures, Part 1: General provisions and buildings, New Delhi, 2016 and IS 1893 (Part1) 2. Bureau of Indian Standards (2016) IS 13920:2016 Indian standard ductile design and detailing of reinforced concrete structures subjected to seismic forces—code of practice, New Delhi 3. Murty CVR, Goswami R, Vijayanarayanan AR, Mehta VV Some concepts in earthquake behaviour of buildings. A Handbook, Gujarat State Disaster Management Authority 4. Jain SK, Murty CVR, Dayal U, Arlekar JN, Chaubey SK (2001) The republic day earthquake in the land of M. K. Gandhi, the Father of the Nation. Learning from Earthquakes (EERI) 5. Choudhary HBK (2009) Effectiveness of some strengthening options for masonry-infilled RC frames with open first story. (ASCE) vol 8, pp 733–745 6. Bhat SA, Setia S, Sehgal VK (2015) Seismic response of moment resisting frame with open ground storey designed as per code provisions. In: Advances in structural engineering. Springer, India, pp 869–883 7. Hejazi F, Jilani S, Noorzaei J, Chieng CY, Jaafar MS, Ali AAA (2011) Effect of soft story on structural response of high-rise buildings. In: IOP series: materials science and engineering. https://doi.org/10.1088/1757-899x/17/1/012034 8. Davis R, Menon D, Prasad AM (2008) Evaluation of magnification factors for open ground storey buildings. In: 14th world conference on earthquake engineering, Beijing, China 9. Choudhury T, Kaushik HB (2018) Seismic fragility of open ground storey RC frames with wall openings for vulnerability assessment. Eng Struct 345–357

A Parametric Study on Soil-Structure Interaction of RC Building with Different Base Conditions L. Lakshmi and C. M. Ravi Kumar

Abstract Soil-structure interaction refers to the effects of supporting soil medium on the motion of structure and its subsequent response during earthquakes. Multistorey buildings could have multiple basements for varied functions, viz. automobile parking, boiler system, air-con system, electrical distribution system and cable TV distribution purpose. This study involves soil-structure interaction analysis of a multistorey building with multiple basements supported on stratified soil medium. The building has ten floors above the ground and 2 below. Response spectrum analysis has been performed on the structure assuming fixed base, flexible base due to homogeneous soil and flexible base due to non-homogeneous or layered soil beneath the foundation using finite element software SAP 2000. Soil properties are included in building model by continuum approach to perform soil-structure interaction analysis. Seismic response of multi-storey building, viz. lateral displacement, storey drift and modal time period is studied for Indian seismic zone V as per I.S. 1893–2002. Presence of non-homogeneous soil beneath foundation of multi-storey structures with basements increases the seismic response of the structure significantly compared to homogeneous soil beneath foundation. Keywords Soil structure interaction · Basement floors · SAP 2000 · Non homogeneous soil strata

L. Lakshmi PG Student, Department of Studies in Civil Engineering, University B.D.T College of Engineering (A Constituent College of Visvesvaraya Technological University, Karnataka), Davangere, India C. M. Ravi Kumar (B) Associate Professor, Department of Studies in Civil Engineering, University B.D.T College of Engineering (A Constituent College of Visvesvaraya Technological University, Karnataka), Davangere, India e-mail: [email protected] © Springer Nature Singapore Pte Ltd. 2021 M. C. Narasimhan et al. (eds.), Trends in Civil Engineering and Challenges for Sustainability, Lecture Notes in Civil Engineering 99, https://doi.org/10.1007/978-981-15-6828-2_12

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1 Introduction Due to increase in population and migration of people from rural to urban areas, the land in the urban areas has become limited resource. Therefore, in urban building construction, the underground basements have become an important component. A cellar or basement floor of a structure which is either totally or halfway beneath the ground floor is commonly utilized as an utility space for a structure, for example, for vehicle leaving, heater framework, cooling framework, electrical dissemination framework and digital TV dispersion point. Be that as it may, in urban areas with high property costs, cellars are frequently fitted out to an elevated expectation and utilized as living space. The multistoried buildings in cities have a feature of multilevel basements which will ease a lack of urban space above the ground. Taipei 101, Taiwan has five floors underground and 101 floors above is a best example of high rise building with multiple basement floors. El Ganainy [1] found that soil-structure interaction impacts are huge if the soil around the cellar floors is delicate when contrasted with firm soil. Accordingly, this examination plans to fuse explicit delicate soil condition around the cellar floors in limited component model, where the soil has a few layers of various attributes. Halabian et al. [2] studied nonlinear behaviour of the soil for the structures with underground stories during seismic excitations. The effect of nonlinear soil-structure interaction is examined by a realistic nonlinear soil model incorporated into the finite difference FLAC software. A practical shear building with underground storey supporting on shallow foundation is considered to study the seismic response when it is subjected to different earthquake excitations. Soil nonlinearity attenuates the bedrock input motion, increases lateral displacement, and base shear may increase or decrease based on type of structure and frequency of input motion. The increase in the normal forces at the soil-structure interface is observed. The present work involves studies on seismic behaviour of the reinforced concrete building with two basement floors considering flexibility of soil around the basements and below the foundation for different mediums involving homogeneous and nonhomogeneous or layered soils, which have soft characteristics.

2 Discriptions of the building The structure considered in this study is a typical reinforced concrete proposed commercial building. The frame has four bays of 6 m every on longitudinal direction four bays of 4.8 m every on cross direction. Building has ten storeys and two basement floors. Height of every storey is 3.2 m, and total height of the building is 38.4 m The plan and elevation showing location of columns and centre lines of beams are shown in Figs. 1 and 2, respectively

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Fig. 1 Centre line of beams and columns (plan)

2.1 Finite Element Modelling Three-dimensional reinforced concrete beam elements are used for simulating beams and columns of the building. It is a two-noded element with six degrees of freedom at each end. Slab and basement walls are modelled as thin plate elements. Restraints are provided to the degrees of freedom for in-plane translations and the rotation about the normal. The section properties of the beam, column and slab assigned in present building are as given in Table 1.

2.2 Loads Following data is taken for modelling the commercial building considered for study. Dead loads are assumed as per IS: 875(Part 1)–1987 and Imposed loads as per IS: 875(Part 2)–1987. Unit weight of materials as per IS: 875(Part- 1) Unit weight of RCC (kN/m3 )

25.00

Unit weight of solid concrete block masonry (kN/m3 )

20.50 (continued)

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(continued) Unit weight of materials as per IS: 875(Part- 1) Unit weight of cement plaster (kN/m3 )

20.40

Live load on slabs as per IS: 875(Part- 2) Live load on floor slabs (kN/m2 ) Live load on basement floor slabs

4.0 (kN/m2 )

5.0

Live load on terrace (kN/m2 )

1.5

Floor finish (kN/m2 )

1.5

2.3 The Finite Element Model Finite element model of the building under consideration without wall elements after assigning loads is shown in the Fig. 3.

3 Modelling and Analysis Response spectrum methodology is employed for seismal analysis. It is proposed to take up investigation of seismic response of a multi-storey R.C.C building with two basement floors for the following conditions at the base, using the response spectrum method of analysis of I.S. 1893–2002 [3].

3.1 Building with Fixed Base The multistoried building is analysed for fixed base condition as is usual in design offices. Fixed condition is obtained by restraining all six degrees of freedom for end node of column such as three displacements (ux ,uy ,uz ) and three rotational degrees of freedom (r x , r y , r z ) at foundation level.

3.2 Building with Homogeneous Soil Beneath Foundation Soil and raft footing are modelled using eight-noded rectangular solid elements with three degrees of freedom at each node. Raft foundation has a plan area of 25.2 m × 20.4 m and depth of 0.75 m which is designed for gravity loads. Soil continuum is

A Parametric Study on Soil-Structure …

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Fig. 2 Centre line of the building (elevation) Table 1 Frame sections Properties

Beam (mm)

Column (mm)

Slab

Basement wall

Size

250 × 450

300 × 900 300 × 750 200 × 600

150 mm

250 mm thick

Material

Concrete

Concrete

Concrete

Concrete

Grade of concrete

M 25

M 30

M 25

M 25

Grade of steel

Fe 415 Fe 500

Fe 415 Fe 500

Fe 415 Fe500

Fe 415 Fe 500

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Fig. 3 Finite element model

extended up to 1.5 times the width of foundation on all four sides of the building, and depth is taken up to 30 m. This assumption is made referring pressure bulb diagram given by Bowles [4]. Soil is modelled by assigning the same material properties for whole soil continuum to get the homogeneous soil condition. The soil parameters considered for this study are listed in Table 2. Table 2 Soil properties and calculated values Soil parameters

Calculated values

SPT No.

N

5

5

Shear wave velocity

Vs

100 × N1/3

171 m/s

Unit weight

γ

By soil test

18 kN/m3

Mass density

ρ

γ /g

1834.86 kg/m3

G

ρ

29,130.27 kN/m2

Shear modulus

Vs2

Poisson’s ratio

μ

0.3–0.35

0.3

Modulus of elasticity

E

2G (1 + μ)

139,493.38 kN/m2

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Fig. 4 2D finite element model of building with homogenous soil beneath foundation

Finite element model of building with homogeneous soil beneath foundation in 2D view is shown in Fig. 4.

3.3 Building with Non-homogeneous Soil Beneath Foundation The procedure of finite element modelling of soil continuum and raft remain same as mentioned for homogeneous soil. But, in place of homogeneous soil, in situ soil profile is taken for the study. The in situ soil profile is taken from ‘Report on geotechnical investigation for the proposed construction of commercial building (Basement + ground + 2 upper floors) at Goa’ prepared by M/S SarathyGeotech & Engineering Services Pvt. Ltd. The soil profile used for study is shown in Fig. 5. Soil properties are calculated using SPT number of each layer as mentioned in Fig. 5. These properties are assigned to the solid elements of respective soil layer in the finite element model. The material properties calculated for each layer of soil are shown in Table 3. Finite element model of the building with non- homogeneous soil layer below the foundation and around the basements after assigning the soil properties for all layers is shown in Fig. 6.

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Fig. 5 In situ soil profile

Table 3 Soil properties and calculated values SPT No.

Shear wave velocity (m/s)

Unit weight (kN/m3 )

Mass density (kg/m3 )

Shear modulus (kN/m2 )

Poisson’s ratio

Modulus of elasticity (kN/m2 )

N

Vs

γ

No.

100 × N1/3

By soil test

ρ

G

μ

E

γ /g

ρ Vs2

0.3–0.35

2G (1 + μ)

2

126

18

1834.86

29,130.27

0.3

75,738.71

3

144.22

18

1834.86

38,164.02

0.3

99,226.40

5

171

18

1834.86

53,651.31

0.3

139,493.38

12

229

19

1936.8

101,570

0.3

264,075.98

37

334

19

1936.8

216,060

0.3

561,760.31

52

373

20

2038.73

1,550,350

0.3

4,030,919.8

Deformed shape of the building after analysis for all three base conditions are shown in Figs. 7, 8 and 9.

A Parametric Study on Soil-Structure …

Fig. 6 2D Finite element model of building with homogenous soil

Fig. 7 Deformed shape of building after analysis

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Fig. 8 Deformed shape of building after analysis (homogenous soil base condition)

Fig. 9 Deformed shape of building after analysis (non-homogenous soil base condition)

4 Results and Discussions Seismic response of the multi-storey building considering base as fixed without SSI, considering SSI with homogeneous soil and non-homogeneous soil beneath

A Parametric Study on Soil-Structure …

149

and around the basements obtained from response spectrum method of analysis in seismic zone V is analysed, compared, and inferences are drawn.

4.1 Lateral Displacement The lateral displacements obtained from response spectrum analysis, for each storey of building model, along both the longitudinal and transverse directions. Maximum displacement is obtained at terrace floor in all seismic zones. Displacements are found to increase with the increase in the zone factor. It is observed that displacement is more in transverse direction than that obtained in longitudinal direction at each storey level (Figs. 10 and 11). Lateral displacement obtained in two soil conditions is compared with fixed base conditions. It is observed that displacement has been increased in top storeys and decreased in bottom storeys. Maximum displacement at the top storey is increased by 1.4 times when soil is considered as homogeneous and 1.68 times when soil is considered as non-homogeneous in longitudinal direction. Along transverse direction, 1.36 times increase is found at for homogeneous soil, and 2 times increase is found for nonhomogeneous soil (Figs. 12 and 13). Fig. 10 Lateral displacement along longitudinal direction

150 Fig. 11 Lateral displacements along longitudinal direction

Fig. 12 Lateral displacement along longitudinal direction

Fig. 13 Lateral displacement along transverse direction

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4.2 Storey Drift Storey drift is determined by the relative displacement of one floor with respect to the displacement above or below. The drifts are plotted with respect to each storey level in both longitudinal and transverse directions. In case of response along longitudinal direction, maximum drift is obtained in storey 6, and in case of transverse direction, maximum drift is obtained in storey 2 in all zones. The curvature has been increased from Zone I to Zone V in both directions. Variation in drift is less at top storeys than in middle storeys (Figs. 14 and 15). Fig. 14 Storey drift along longitudinal direction

Fig. 15 Storey drift along transverse direction

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Storey drift obtained in homogeneous and non-homogeneous soil conditions is compared with fixed base conditions in all zones. The study of tables and graphs of storey drift comparison in all zones shows that in case of fixed base building, storey drift plot takes the shape of parabola from basement storey to terrace. But in case of flexible base buildings, plots take the shape of parabola from ground storey to terrace. Drift has been increased from 1.6 to 2 times in case of homogeneous soil base and 1.9–2.3 times in case of non-homogeneous soil base. Maximum drift has occurred at storey 5 in all three conditions and in all zones (Figs. 16 and 17). Fig. 16 Storey drift along longitudinal direction for different base conditions

Fig. 17 Storey drift along transverse direction for different base conditions

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4.3 Modal Time Period Modal natural period of any mode is the time period of vibration in that mode, and they are plotted against the mode number as shown in Fig. 19. It is observed that a large decrement in modal period up to mode 4 and thereafter decrement is very less up to last mode. Modal time period for fixed base and flexible base building has not shown significant difference. Modal time period is 3.3 s in first mode. It has decreased sharply up to fifth mode, and thereafter, decrement is very less up to last mode. Natural time period plot for all three conditions is shown in Figs. 18 and 19. Fig. 18 Modal natural period

Fig. 19 Modal natural period for different base conditions

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4.4 Base Shear Base shear is the total design lateral force at the base of a structure. Base shear has been increased from Zone I to Zone IV in both directions, and also, the base shear in each zone is more in case of longitudinal direction to that of transverse direction of building. Base shear has been increased consistently in all zones. It has been increased 1.2 times for homogeneous flexible base and 1.39 times for non-homogeneous flexible base condition when compared to fixed base condition in longitudinal direction. The increment is about 1.22 times for homogeneous flexible base and 1.45 times for non-homogeneous flexible base condition when compared to fixed base condition in transverse direction (Figs. 20 and 21). Fig. 20 Base shear

Fig. 21 Base shear for different base conditions

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155

5 Conclusions The investigation of seismic responses for a multi-storey reinforced concrete building with two basement floors considering soil-structure interaction has been carried out using response spectrum analysis. Flexible base has been incorporated using continuum approach. Responses such as lateral displacement, storey drift, base shear and modal period are found for the building for fixed base without SSI, considering SSI with homogeneous soil, and non-homogeneous soils beneath the foundation and around the basement floors. The results have been analysed and compared. Here, broad conclusions are drawn from the study. • Seismic response of multistoried building increases for buildings founded on soft soil deposits than fixed base buildings. Thus, soil-structure interaction should be considered in multistoried buildings. • Responses are negligible in underground floors. But, displacements, storey drift and base shear in the building have increased when SSI is considered with homogeneous soil beneath the foundation and around the basement floors. • Presence of layered soils in foundation beneath the raft increases the seismic responses significantly and needs consideration in design. Carrying out in situ soil profile, establishing their properties and including them in the finite element model for seismic response analysis, is necessary.

References 1. El Ganainy H, El Naggar MH (2009) Seismic performance of three-dimensional frame structures with underground stories. Soil Dynam Earthquake Eng 2. Halabian AH et al (2008) Seismic response of structures with underground stories considering non-linear soil-structure interaction. In: International conference on case histories in geotechnical engineering 3. IS 1893(Part-I)-2002 Criteria for earthquake resistant design of structure. General provisions and Buildings, Bureau of Indian Standards, New Delhi 4. Bowles JE (2001) Foundation analysis and design. McGraw-Hill International Editions 5. Khoueiry DH, FaridKhouri M (2015) Integrating soil structure interaction along basement walls in structural analysis programs. Int J Dev Res

Bibliography 1. Krishnamoorthy A, Anita S (2014) Seismic effect of soil structure interaction on plane frame structures. IOSR J Mech Civil Eng 2. Emadi A et al (2014) Investigation of beneficial and detrimental effects of soil-foundationstructure interaction on the seismic response of shear buildings. KSCE J Civil Eng 3. Matinmanesha H, Asheghabadib MS Seismic analysis on soil-structure interaction of buildings over sandy soil. In: The Twelfth East Asia-Pacific conference on structural engineering and construction, Procedia Engineering

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4. Kuladeepu MN et al (2015) Soil structure interaction effect on dynamic behavior of 3D building frames with raft footing. Int J Res Eng Technol 5. Agarwal P, Shrikhande M (2006) Earthquake resistant design of structures. PHI Learning Private Limited 6. Cook RD et al (2004) Concepts and applications of finite element analysis. Wiley India (P.) Ltd. 7. Jain AK (2011) Reinforced concrete, limit state method. Nem Chand and Bros, Roorkee

Effect of Diaphragm Discontinuity on the Seismic Response of an RC Building Vincle Mable Vas, Prajwal Nagaraja, and Katta Venkataramana

Abstract Although rigid floor diaphragm is a reasonable assumption for seismic analysis, certain building configurations may exhibit diaphragm flexibility. Detailed investigations have been carried out on modelling of flexible diaphragms compliant with various codes such as ASCE-07 and UBC 1997. Studies have shown that diaphragm flexibility amplifies both the deformation and the shear in the diaphragm. However, additional studies are essential to assess the magnitude of such amplification and to account for it in the design. The methodology is outlined by three major elements such as the choice of building models, the adopted method of analysis and the parameters studied. Buildings with large cut-outs and openings are observed to exhibit flexible behaviour. These models are analysed dynamically using a sitespecific response spectrum developed from probabilistic seismic hazard analysis (PSHA) for Mangalore region (a coastal city in Karnataka, Southern India). The analysis is carried out using a G+10 RC building. The effect of percentage of openings in the diaphragm is studied using structural parameters such as storey drift, base shear and storey displacement with the help of ETABS 2015 software, and the optimum shape for these openings in a building plan is finalized. Further, time history analysis is performed over the models, and the results obtained through response spectrum and time history analysis are compared. The study highlights the importance of diaphragm flexibility in determining the seismic response of a building. This flexibility causes significant increase in the building period, which results in reduction in the earthquake-induced base shear. Since the seismic input used for the study was developed for the moderate seismic zone, the outcomes of this investigation are believed to have vast applications. V. Mable Vas · P. Nagaraja · K. Venkataramana (B) Civil Engineering Department, National Institute of Technology Karnataka, Surathkal, Mangalore, Karnataka 575025, India e-mail: [email protected] V. Mable Vas e-mail: [email protected] P. Nagaraja e-mail: [email protected] © Springer Nature Singapore Pte Ltd. 2021 M. C. Narasimhan et al. (eds.), Trends in Civil Engineering and Challenges for Sustainability, Lecture Notes in Civil Engineering 99, https://doi.org/10.1007/978-981-15-6828-2_13

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Keywords Response spectrum · Probability seismic hazard analysis · Building period · Base shear · Time history analysis

1 Introduction In the analysis of majority of the RC buildings, diaphragm slabs are assumed to be rigid. However, in reality, there can be significant amount of in-plane deformation, especially in case of thin floor plans and buildings with large cut-outs. This deformation is further amplified when the building is subjected to seismic forces. Hence, there exists a necessity to evaluate the impact of diaphragm flexibility on such buildings. Initially, a parametric study is undertaken over a set of models by varying the percentage of opening. This is carried out using a site-specific response spectrum developed from probabilistic seismic hazard analysis (PSHA) for Mangalore region (a coastal city in Karnataka, Southern India) with the help of ETABS 2015 software. Structural parameters like storey drift, storey displacement and base shear are evaluated and plotted to arrive at the optimum percentage and suitable location of opening to ensure minimum diaphragm flexibility. Further, time history analysis is performed over the models by taking data of El Centro earthquake (magnitude 6.9), and the results obtained through response spectrum and time history analysis are compared. A diaphragm is a horizontal structural element that transmits lateral loads to the vertical load resisting elements of a structure. They are generally horizontal but can sometimes be sloped. The lateral loads to be resisted are wind and earthquake loads. Diaphragms can either be flexible or rigid. A diaphragm is considered as rigid when its displacement at the midpoint is lesser than twice the average displacements at its ends. If the maximum lateral deformation of the diaphragm is more than two times that of the associated storey, the diaphragm may be considered to be flexible. Various codes provide different definitions for the flexibility of diaphragms. According to IS 1893 (Part 1) 2002 [1], if the maximum lateral displacement at midpoint of the diaphragm is greater than 1.5 times the average displacement of the entire diaphragm, the diaphragm maybe considered to be a flexible diaphragm. In case of ASCE 7-05 (minimum design loads for buildings and other structures) and the 3rd edition of Iranian Code of Practice for Seismic Resistant Design of Buildings (Standard No. 2800), the maximum lateral displacement must be greater than twice the average displacement. Section 1630.6 of the 1997 Uniform Building Code states that diaphragms shall be considered flexible when the maximum lateral deformation is more than twice the average storey drift of the associated storey. This flexibility is considered in order to distribute torsional moment and storey shear. In addition to this, Eurocode 8 suggests that the diaphragm is taken as being rigid, if its horizontal displacements are lesser than those obtained from the rigid diaphragm assumption by more than 10% of the displacements for the seismic design condition. This shows that various codes have given similar definitions for diaphragm flexibility.

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159

2 Objective • To analyse the variations in diaphragm flexibility of an RC building on changing the percentage of openings. • To understand the behaviour of the structure with respect to diaphragm flexibility. • To determine the optimum shape of openings for a building. • To compare the results obtained from response spectrum and time history analysis.

3 Literature Review • Maniar and John [2] The effect of diaphragm discontinuity was studied by varying opening percentages and considering six different G+7 storey models. Through linear static analysis, it was observed that the behaviour of the building is better when diaphragm discontinuity is closer to the centre of the building [2]. • Vinod Kumar and Gundakalle [3] Nonlinear static (pushover) analysis is performed over a multistoreyed building with diaphragm openings, and its behaviour is analysed by varying percentages of diaphragm openings for seismic parameters like maximum dead load, modal time period, maximum storey drift and base shear. Models with symmetrical openings expressed similar responses for all parameters, while models with change in symmetry behaved differently [3]. • Khaloo et al. [4] The influence of diaphragm opening on seismic response of buildings with end shear walls was evaluated using nonlinear dynamic and static analysis. The error obtained due to rigid diaphragm assumption and changes in these errors when there are openings in the diaphragm were investigated [4]. From the literature survey conducted, it was observed that there has not been enough research to vary the percentage of opening for a G+10 RC building by conducting site-specific response spectrum for Mangalore region. Considering the shapes of openings that were previously used, we arrived at six models whose opening shapes were not considered earlier. In addition to this, no significant attempt has been made to check the effect of diaphragm discontinuity before and after incorporating shear walls. Hence, six different models were considered by using the data from Mangalore region for the current study. In future, we aim to compare the behaviour of the building before and after incorporating shear walls.

160 Table 1 Description of the models

V. Mable Vas et al. Model

Percentage opening (%)

1

0

2

4

3

12

4

20

5

20

6

36

4 Methodology For this study, 11-story (G+10) building with a 3-m height for each storey and 3.5 m for the ground storey is modelled. These buildings were analysed according to the Indian Standard Code IS 1893 (Part I) [1]. Fixed joints are provided at the building base. All the structural sections are assumed to be rectangular. The buildings are modelled using nonlinear finite element software ETABS 2015 software. Analysis was done using the response spectrum method. Six different models were studied in seismic zone III by comparing storey displacement, storey drift and base shear for all models. All diaphragms were assumed to be semi-rigid. The description of the models is as follows (Table 1). The difference between Model 4 and Model 5 lies in the shape of the opening as shown in Figs. 5 and 6 (Figs. 1, 2, 3, 4 and 7; Tables 2, 3, 4 and 5).

5 Methods Applied Response spectrum analysis: It is a linear, dynamic and elastic analysis which computes the contribution from all the natural vibrational modes in order to obtain the maximum response of any structure under earthquake. This type of analysis is based on the fundamental principles of structural dynamics and vibrations. Response spectrum analysis is applicable to investigation of the dynamic response of structures. Features of response spectrum analysis are • The building is assumed to be in its elastic state, that is, no yielding occurs. • For every modal response, 5% damping is considered. Time History analysis: All structures will behave dynamically when they are subjected to loads or displacements. Due to gradual application of these loads and displacements, the inertia forces can be ignored, and static load analysis can be used. Hence, dynamic analysis is an extension of static analysis. In time history analysis, the response of the building is computed at a series of subsequent time intervals. Time history analysis is used for linear and nonlinear

Effect of Diaphragm Discontinuity on the Seismic … Fig. 1 RC frame building with 12% opening (3D View)

Fig. 2 Plan of RC frame building with no opening

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Fig. 3 Plan of RC frame building with 4% opening

Fig. 4 Plan of RC frame building with 12% opening

evaluation of dynamic structural response under loading, which varies according to the time function.

Effect of Diaphragm Discontinuity on the Seismic … Fig. 5 Plan of RC frame building with 20% (A) opening

Fig. 6 Plan of RC frame building with 20% (B) opening

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Fig. 7 Plan of RC frame building with 36% opening

Table 2 Structural properties of the building

Table 3 Material properties

Table 4 Loads

S. No.

Specification

Size

1

Plan dimensions

20 m * 20 m

2

Floor to floor height

3m

3

Base floor height

3.5 m

4

Total height of building

33.5 m

5

Slab thickness

150 mm

6

Floor beam size

300 mm * 450 mm

7

Column size

450 mm * 600 mm

8

Wall thickness

230 mm

S. No.

Materials

Grade

1

Grade of concrete

M 30

2

Grade of steel

Fe 415

S. No.

Loads

Assumed value

1

Dead load

Calculated as per self-weight

2

Floor finish

1.5 kN/m2

3

Live load

3 kN/m2

4

Roof load

2 kN/m2

5

Seismic load

Calculated as per IS:1893-2002

Effect of Diaphragm Discontinuity on the Seismic … Table 5 Factors for seismic design

Table 6 Response spectrum values

Table 7 Natural period calculated using response spectrum

165

S. No.

Factors

Assumed value

1

Seismic load

IS 1893:2002

2

Zone factor

User defined

3

Importance factor

1

4

Response reduction factor

5

Model

Max storey displacement (mm)

Max storey drifts (10−4 )

Max storey shear (kN)

1

10.01

8.51

1036.33

2

9.98

8.49

1029.16

3

10.04

8.57

1004.07

4

9.90

8.43

945.12

5

9.86

8.37

999.55

6

9.86

8.39

801.94

Model

Natural period (s)

1

1.57

2

1.56

3

1.58

4

1.55

5

1.54

6

1.54

6 Results and Discussions 6.1 Response Spectrum Table 6 indicates the maximum storey displacement, storey drift, storey shear, and Table 7 indicates natural period for the following models using response spectrum analysis.

6.2 Time History Table 8 indicates the maximum storey displacement, storey shear, and Table 9 indicates the natural period for the following models:

166 Table 8 Time history values

Table 9 Natural period calculated using time history

V. Mable Vas et al. Model

Max storey displacement (mm)

Max storey shear (kN)

1

9.72

899.11

2

9.70

892.23

3

9.78

845.06

4

9.62

821.27

5

9.55

864.27

6

9.62

698.44

Model

Natural period (s)

1

1.56

2

1.55

3

1.57

4

1.54

5

1.53

6

1.53

Fig. 8 Displacement versus Time graph for 0% opening

Graphs of maximum displacement versus time were plotted using time history analysis for the models. The graphs obtained were as follows (Figs. 8, 9, 10, 11, 12 and 13).

6.3 Comparison Between Response Spectrum and Time History Analysis Figures 14 and 15 show the comparison between response spectrum and time history analysis for maximum displacement and maximum shear.

Effect of Diaphragm Discontinuity on the Seismic … Fig. 9 Displacement versus Time graph for 4% opening

Fig. 10 Displacement versus Time graph for 12% opening

Fig. 11 Displacement versus Time Graph for 20% (A) opening

Fig. 12 Displacement versus Time graph for 20% (B) opening

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Fig. 13 Displacement versus Time graph for 36% opening

Fig. 14 Comparison for maximum displacement versus percentage opening

Fig. 15 Comparison for maximum shear versus percentage opening

6.4 Inference • In case of response spectrum analysis, maximum storey displacement was observed in building with 12% opening. This could be because the aspect ratio of the opening is not equal to unity. However, all the other models have openings with unit aspect ratio. Least storey displacement was observed in building with 20% opening. • Maximum storey drift was observed in the third storey of all the models, and the highest magnitude was recorded in building with 12% opening and least in building with 20% opening.

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• Maximum storey shear decreases with increase in percentage opening, irrespective of the amount of increase in the opening. This can be accounted to the decrease in seismic weight of the building which, in turn, decreases the storey shear of the building. • Graphs of storey displacement and storey drift follow a similar trend. • Although models 4 and 5 have 20% opening each, model 5 exhibits lesser storey displacement and drift due to the shape of the opening. • In case of time history analysis, maximum storey displacement was observed in building with 12% opening due to the presence of an unsymmetrical opening. Least storey displacement was observed in building with 20% (B) opening. • Maximum storey shear was observed in the building with no opening, and least storey shear was observed in building with 36% opening. This is because the storey shear is directly proportional to the seismic weight of the building. • Figures 14 and 15 also show that the values obtained from time history analysis are lesser than those obtained from response spectrum analysis.

7 Conclusions and Scope for Future Study 7.1 Conclusions • Buildings with uniform and symmetrical openings perform better than those with unsymmetrical openings. • As increase in openings can decrease the seismic weight of the building, diaphragm discontinuity due to openings does not significantly affect the storey shear. • Values obtained through time history analysis are lesser than those obtained from response spectrum analysis. • Since the maximum storey displacement observed in the models is negligent, RC buildings can be provided with openings up to 36% to improve ventilation and aesthetic performance of the building.

7.2 Scope for Future Study For future research, shear walls can be incorporated into the models to check for variation in flexibility. Column geometry (square, rectangular and circular) can also be altered to observe the trend with respect to in-plane stiffness variation. Acknowledgements We express our deepest sense of gratitude to Dr. Varghese George, Professor and Head, Department of Civil Engineering, NITK, for extending all necessary support to present and complete the work being reported in this paper. We also extend our heartfelt thanks to our Faculty Advisor, Basavaraju Manu, Associate Professor, Department of Civil Engineering, NITK,

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for giving us this opportunity to take up this project. We would also like to thank all the Teaching and Non-Teaching Staff of Civil Engineering Department.

References 1. IS 1893 (Part-1) (2002) Indian standard criteria for earthquake resistant design of structures (5th Revision) 2. Maniar O, John RJ (2015) Effect of diaphragm discontinuity on seismic response of multi-storied building. Int J Emerg Technol Adv Eng 05(12) 3. Vinod Kumar PP, Gundakalle VD (2015) Effect of diaphragm openings in multi-storeyed RC framed buildings using pushover analysis. Int Res J Eng Technol (IRJET) 4. Khaloo AR, Masoomi H, Nozhati S, Mohamadi Dehcheshmeh M (2016) Infuence of diaphragm opening on seismic response of rectangular RC buildings with end shear walls. Scientia Iranica A 23(4):1689–1698

Study on Effects of Hooked-End Steel Fiber-Reinforced Concrete Anil Kumar, N. R. Pavan Prasad, and S. K. Sujith

Abstract With the growing interest in the use of fiber-reinforced concrete in the construction industry, attempts have been made to clarify its performance have become important. This study investigates the effect of steel fiber-reinforced concrete. Generally, steel fiber is used for mitigating the cracks width and enhancing in the concrete member strength. In this present investigation, the study is carried out using steel fiber as reinforcement in concrete (hooked end). In this investigation, properties such as workability of concrete, compressive strength, split tensile strength and flexural strength of the different percentage (0, 0.5, 1, 1.5, 2%) of steel fiber were carried. From the experimental investigation results, it is noted that, by the inclusion of the steel fiber (hooked end), ductility of concrete improved by increasing fiber percentage in concrete. The use of hooked steel fibres also resulted in increase in the load bearing capacity, reduction in cracks and increase in flexural capacity of concrete. Keywords Steel fibre · Workability · Flexural capacity · Ductility · Fiber reinforced concrete

A. Kumar Department of Civil Engineering, NMAM Institute of Technology, Nitte, Karkala, Udupi, Karnataka 574110, India e-mail: [email protected] N. R. Pavan Prasad (B) NMAM Institute of Technology, Nitte, Karkala, Karnataka, India e-mail: [email protected] S. K. Sujith Department of Civil Engineering, Nagarjuna College of Engineering and Technology, Bengaluru, Karnataka, India e-mail: [email protected] © Springer Nature Singapore Pte Ltd. 2021 M. C. Narasimhan et al. (eds.), Trends in Civil Engineering and Challenges for Sustainability, Lecture Notes in Civil Engineering 99, https://doi.org/10.1007/978-981-15-6828-2_14

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1 Introduction Use of concrete increases day by day due to its high compressive strength, resistance to fire, less maintenance cost, high resistance to water which include long service. Similarly, it has many drawbacks, which consist of poor in tensile strength and low in ductility. Significantly, to increase the integral properties such as tension, concrete member has to withstand against high tensile strength, and it reinforced with continuous reinforcing bars due its strength and lack of ductility. Moreover, the concept of steel reinforcement in concrete member is introduced mainly to withstand against tensile and shear stresses which act at critical lactation. By the inclusion of fiber in concrete member, it significantly increases the strength property of concrete. One of the main disadvantage of improper curing is the development of microcracks. And this rapidly propagates into formation of cracks over applied load that is mainly accountable for the low tensile strength of concrete. Hence, to overcome these drawbacks, steel fibers are added in concrete. To develop concrete properties, inclusion of steel fibers was brought in solution in view of increasing its flexural and tensile property of concrete. The fiber-reinforced concrete is used primarily to improve tensile strength and increase toughness. By increasing the strength, brittleness of the concrete also increases. In the present time, fiber-reinforced concrete (FRC) is used in the many structural applications. Now, a day’s different kinds of fibers have been used in concrete to reinforcement. Generally, the fibres used in the concrete are in the form of discontinuous and in random manner. Steel fibers are one such kind of fibers which are most commonly used as it has stiffness. The scope of steel fiber-reinforced concrete (SFRC), which enhances tensile strength of concrete, improves ductility and mitigates the cracks in concrete. From the past research it is found that, these fibres could be effectively used in the improvement of concrete properties. It is noted that by increase in aspect ratio, the strength property of concrete also increases, and flexure strength decreases with decrease in the aspect ratio [1, 2]. Ductility of concrete increases by addition in percentage of fibers content [3]. Decrease in fiber volume increases the scattering of fiber in concrete. And, higher aspect ratio results in poor workability of the concrete [4]. With increase in steel fiber, volume strength property of the concrete member goes on increasing [5]. The peak load and toughness of the concrete specimen increase with increase in fiber content [6]. Compressive strength mainly influences fiber content and water cement ratio rather than fiber orientation, and flexural strength primarily depends on the strength of the fiber matrix, and it is independent of fiber content and orientation [7]. If there is increase in the steel fiber content, flexural strength of the member increases greatly [8]. Presently, in some of research investigations marked that, by the addition of steel fibers as reinforcement, ductility was improved by randomly distributed fibers. In this experimental investigation, effect of hooked-end steel fibers on workability of

Study on Effects of Hooked-End Steel … Table 1 Physical properties of cement

Properties

173 Obtained values

Specific gravity

3.12

Initial setting time (min)

85

Final setting time (min)

330

Standard consistency

34%

concrete, compressive strength, splitting tensile and flexural strength of concrete was studied. Present investigation was carried by using steel fiber (hooked end) with aspect ratio 53.85 (L/D) was used. Mix was made with four different fiber volume fractions where steel fibers were added by weight of concrete to mix in terms of 0.5%, 1, 1.5 and 2%. Total five concrete mixes were prepared (1 conventional + 4 SFRC). An average of 38 MPa of compressive strength was preferred. Tests were conducted after a curing period of 28 days.

2 Material Specification 2.1 Cement In the current investigation, cement (Ultra Tech-53 grade OPC) conforming to IS: 12269-1987 was used and designed for strength about 38 MPa after 28 days of curing (Table 1).

2.2 Fine Aggregate For the present study, locally available sand (river sand) was used as fine aggregate conforming to IS: 383-2016. This was naturally disintegrated and free from silt and clay. Fine aggregate physical properties are tabulated below in Table 2. Table 2 Physical properties of fine aggregate

Properties

Obtained values

Specific gravity

2.59

Water absorption

1.30%

Fineness modulus

3.31

Grading zone

Zone III

174 Table 3 Physical properties of coarse aggregate

A. Kumar et al. Properties

Obtained values

Type of aggregate

Crushed angular

Specific gravity

2.69

Water absorption

0.4%

Fineness modulus

4.57

Fig. 1 Hooked-end steel fiber used in this study

2.3 Coarse Aggregate In this work, locally available crushed aggregate belonging to 20 mm down conformed by IS 383-2016 was been used (Table 3).

2.4 Steel Fibers A hooked-end steel fiber was used for the investigation (Fig. 1). The fibers have a length 35 mm and diameter 0.65 mm. Aspect ratio is 53.85, and tolerance for dead load is = ±10%.

2.5 Water Available tap water was used in present investigation, and which is fit for drinking, and it is used for both mixing and curing. Water is maintained at constant pH of 6–8.

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Table 4 Concrete mix proportion Grade

Cement (kg/m3 )

Fine aggregate (kg/m3 )

Coarse aggregate (kg/m3 )

Water (l/m3 )

M30

340

744.48

1154.3

153.0

2.6 Superplasticizer CONPLAST SP430 was used in this study to accelerate the strength gaining property, minimize the permeability and to develop the workability of concrete.

2.7 Concrete Production Concrete mixes were designed for target strength of 38 MPa based on trial mix design procedure as per IS 10262-2009. The different mixes of concrete (plain and fiber-reinforced concrete) were prepared as shown above in Table 4. Fiber-reinforced concrete mixes show lower workability. So, it is essential to add superplasticizer to obtain 80–100 mm slump. Various fiber-reinforced concrete mixes were prepared in which hooked-end steel fibers were added in concrete mix with random dispersion of steel fibers. The superplasticizer (CONPLAST-SP430) up to the required dosage of 0.7% by cement weight was added to the mix, and by this, required target slump 80–90 mm by trial and error method is obtained. It is observed that the workability concrete mix with fiber-reinforced concrete mix was noted in between 80 mm and 90 mm slump. This is enough that concrete can be found that easy placing of concrete. And, the ultimate superplasticizer dosage was limited to 2%. Fibers were added in different proportions (0.5–2.0%) after the cohesive mix of the concrete in the mixer, to maintain the uniform dispersion of the steel fibers and minimize balling effect of the fibers and segregation. The mix is transferred to the mold and compacted through vibration, after about 24 h demolded and cured for required period of days.

3 Experimental Methodology 3.1 Workability Test Test on workability of concrete is done by slump cone test as per IS: 1199-1959, both ordinary and SFRC mix.

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Fig. 2 Compression test setup

3.2 Compressive Strength Test Compression test on harden concrete is the most regular test which is conducted on concrete specimens. Compression test is carried on specimen size of specimen is 150 × 150 × 150 mm and casted for M30 concrete and after curing for required days. As per standards, IS: 516-1959 and cubes after 28 days of curing were tested under compression testing machine. The ultimate load carried by specimen was computed. In each set, three cubes were examined, and average compressive strength is computed by using the formula as follows (Fig. 2). Compressive strength =

Load MPa Area

3.3 Split Tensile Strength Split tensile test was conducted on standard cylinder specimens of size 150 × 300 mm cylinders as per IS 5816:1999. In each set, three cylinder molds were examined, and average strength is noted. The split tensile strength of cylinder was computed as follows (Fig. 3). Split tensile strength = where L specimen length

2∗ P MPa π ∗L ∗d

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Fig. 3 Split tensile test setup

D specimen diameter.

3.4 Flexural Strength It is bending strength of the concrete beam before yield. The specimens were tested as per IS 516:1959, under two points loading. The failure load is observed in every beam specimen. The beams were examined, and values were noted for every three beams. The flexural strength of concrete beam was computed as follows (Fig. 4). Fig. 4 Flexural strength test setup

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Fig. 5 Workability of concrete due to inclusion of fibers

Flexural strength =

P∗L MPa b∗d

where P L b d

Load at failure point, Distance between two supports = 400 mm, Width of specimen = 50 mm, Depth of specimen = 50 mm.

4 Results and Discussion 4.1 Workability Test Fresh concrete workability was evaluated by the slump cone test with water cement ratio 0.45. Similarly, in a conventional concrete mix, workability mainly depends on admixture type, its content and mix proportion. But in fiber-reinforced concrete content, workability depends on types of fiber, properties and content. Here, workability mainly influences fiber content added in cement matrix and its type (hooked end). The results on effect of steel fibers on workability are shown below (Fig. 5).

4.2 Compressive Strength Compressive strength which given in above figure gives clear evidence that steel fiber has low efficiency to enhance the compressive strength of the concrete. And concrete maximum compressive strength is noted about 42.52 N/mm2 for 1.5% of fiber content. In which, concrete shows marginal improvement in compressive strength of about 16.49% for 7-day strength and 11.25% 28-day strength when compared with the0conventional concrete. It noted that the fiber in the concrete

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effectively stressed and the crack opening is caused due to shear stress of fiber in concrete instead of crushing. This results in strength increase around 11 and 16% which can be obtained from the FRC. When tested, it is observed that the failure cracks pass through the aggregates. So, for bridging, the cracks steel fibers were used in concrete (Fig. 6). In compression, failure cracks occur because of tensile failure and rather than of crushing failure. Here, bridging of the steel fiber is experienced. The fibres intermixed with the cement concrete provided enough confinement which influenced in the enhancement of strength. And it is found from the above figure the strength of the FRC is better than the conventional concrete (Fig. 7). Fig. 6 Compressive test results on 7 and 28 days

Fig. 7 Cracks opening due to shear stress

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Fig. 8 Split tensile strength test results on 7 and 28 days

4.3 Split Tensile Strength Split tensile strength of conventional and SFRC test result are provided above. It is noted that there is an enhancement in the tensile property of concrete by increasing the fiber content. Split tensile strength of the SFRC increased compared to conventional and is found to be 51.29% for 7 days and 43.16% for 28 days, and these variations are found for the 1.5% of fiber volume in mix. Hence, hear bridging of cracks found by preventing the expansion of the width of the crack. Here, tensile strength is absorbed by the steel fiber, and cracks are arrested by the steel fibers. Performance of concrete service in crack control plays a very crucial part. The over stressing of load in harden concrete leads to cracking, and leads to failure of concrete member. So, the inclusion of hooked-end steel fibers is an effective way to mitigate the cracks in the concrete. Thus, fiber-reinforced concrete is useful for resisting the formation of cracks which is found in concrete (Figs. 8 and 9).

4.4 Flexural Strength Flexural strength test of concrete as shown in Fig. 10 gives enough merits to support the properties of SFRC. From the experimental test results, it is noted that above results provide clear evidence in increasing flexural strength as compared to conventional concrete. The above graphical representation shows that positive effect in the flexural strength contains randomly dispersed steel fibers. The maximum flexural strength is found to be 4.65 N/mm2 for 7 days’ strength and 5.13 N/mm2 for 28 days’ strength. By the inclusion of steel fibers, there is an enhance in flexural strength by 53.45% for 7 days and 49.56% for 28 days for 1.5% inclusion of hooked steel fibers concretes compared to conventional concrete. The fiber end anchorages which were found in hooked-end steel fiber were found to have an impact in increasing the flexural properties fibers incorporated concrete specimens. When it is compared with conventional

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Fig. 9 Bridging of cracks width

Fig. 10 Flexural strength results on 7 and 28 days

concrete, flexural strength was enhanced by an increasing in steel fiber addition. By the addition in percentage of steel fibers increased, simultaneous flexural strength of concrete is improved. This may be due to the anchorage which is provided by hookedend steel fiber. This improvement is due to pullout resistant which is provided by steel fiber (hooked end) which is present in the concrete composition. Steel fiber with 1.5% had great influence on an enhancement in flexural strength of SFRC. From the test results, it is noted that flexural strength of plain cement concrete can be increased by inclusion of the steel fibers. Most notably, flexural properties of SFRC were higher than plain cement concretes. From test results, it is noted that SFRC has positive effect on flexural strengthening of concrete beams (Fig. 11).

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Fig. 11 Straining of hooked-end fiber due to pullout effect

5 Conclusion • It is found that by the inclusion of steel fiber percentage, there is an enhancement in the compressive strength, split tensile strength and flexural strength of concrete. • Workability of FRC gradually decreases by an increase in addition of the steel fibers. • By increase in inclusion of steel fibers, gradual enhance in the ductility of the concrete is observed. • As the fiber content increases, reduction the crack is observed in the concrete. • From the compressive strength, there is increase in strength by 11.25% for 28 days, and there is a marginal enhance in the strength, and it is concluded that hooked-end fiber was strained effectively by carrying stress. • By the split tensile strength test, it is noted that expansion of cracks width is prevented by the steel fibers by the bridging action. • From the study, it was also found that flexural strength was improved greatly by hooked-end steel fiber may be due to anchorage reinforcing efficiency.

References 1. Sable KS, Rathi MK (2012) Effect of different type of steel fibre and aspect ratio on mechanical properties of self compacted concrete. Int J Eng Innovative Technol (IJEIT) 2:184–188 2. Vinayak BS, Gunderao N (2017) Evaluation of the strength properties of hooked end steel fiber reinforced concrete produced with fly ash. Int Res J Eng Technol (IRJET) 04:2275–2278 3. Ghaffar A, Chavha AS, Tatwawadi RS (2014) Steel fibre reinforced concrete. Int J Eng Trends and Technol (IJETT) 9:791–797

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4. Devi TK, Singh TB (2013) Effects of steel fibres in reinforced concrete. Int J Eng Res Technol (IJERT) 2:2906–2913 5. Yazıcı S, Inan G, Tabak V (2007) Effect of aspect ratio and volume fraction of steel fiber on the mechanical properties of SFRC. Constr Build Mater 21:1250–1253 6. Zhang S, Zhang C, Liao L (2019) Investigation on the relationship between the steel fibre distribution and the post-cracking behaviour of SFRC. Constr Build Mater 200:539–550 7. Huang H, Gao X, Li L, Wang H (2018) Improvement effect of steel fiber orientation control on mechanical performance of UHPC. Constr Build Mater 188:709–721 8. Gencel O, Brostow W, Datashvili T, Thedford M (2012) Workability and mechanical performance of steel fiber reinforced self-compacting concrete with fly ash. Compos Interfaces 18:169–184

Seismic Behaviour and Comparison of Different Slab System Diagrid Structure C. Rahul and J. K. Lokesh

Abstract Diagrid system for tall building has evolved as efficient system in terms of lateral stiffness. In this study, an attempt has been made to study the seismic response of diagrid structure with different slab system (conventional slab, i.e. with beam and flat slab) by using response spectrum analysis. The models studied are square in plan with aspect ratio H/B (where H is the total height and B is the width of structure) as 3.1. Five different diagrid angles 41°, 50°, 56°, 61° and 64° are considered. Earthquake analysis is carried out according to IS 1893:2002(Part-1). Based on the study, the efficiency of slab system and optimum diagrid angle is presented in terms of storey displacement and storey shear. Keywords Seismic analysis · Diagrid · Optimum angle · Displacement and shear

1 Introduction The number of tall structures construction has been rapidly increasing worldwide, and these structures involve various complex factors such as economics, aesthetics, technology and policies. Advancements in structural engineering and technology have significantly pushed the height limit of high-rise buildings. Tall buildings became popular in the late nineteenth century in the USA. The twenty-first century has emerged for rapid development of high-rise buildings. Countries in Asia such as China, South Korea, Japan, Malaysia and especially Middle East such as Dubai have become the hub of high-rise structures. India is also catching up the speed lately. With increase in the height of structures, the lateral load resistance becomes critical issue and concern than the gravity load. There are many lateral load resisting systems developed and are widely used such as rigid frame, shear wall, core wall, braced tube C. Rahul (B) · J. K. Lokesh Department of Civil Engineering, NMAM Institute of Technology, Nitte, Karkala, Udupi District, Karnataka 574110, India e-mail: [email protected] J. K. Lokesh e-mail: [email protected] © Springer Nature Singapore Pte Ltd. 2021 M. C. Narasimhan et al. (eds.), Trends in Civil Engineering and Challenges for Sustainability, Lecture Notes in Civil Engineering 99, https://doi.org/10.1007/978-981-15-6828-2_15

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system, outrigger, belt truss structures and tube system structures. Diagrid system is adopted in tall structure because of its structural efficiency to resist both gravity and lateral load by axial stresses of its members and flexibility in architectural planning. Diagrid system is an exterior structural where the perimeter vertical columns (support members) are eliminated and consists of only inclined columns (diagonal members) on the façade of the structure. Shear and overturning moment developed in the system are resisted by axial action of the diagonal members when compared to bending of vertical columns in framed tube structure. There are many examples of diagrid systems adopted in tall structures all around the world; some are Swiss Re (London), Hearst Tower (New York), Lotto Super Tower (Korea), Capital Gate Tower (Abu Dhabi) shown in Figs. 1, 2, 3 and 4, respectively. The inclined members in the diagrid structure are capable of carrying both lateral load as well as gravity load. The topography of the structure and the angle of inclination of diagonal members with horizontal are the two key factors affecting the stiffness laterally and efficiency of diagrid structure. The optimum angle of diagrid depends on many factors such as the storey height, aspect ratio, lateral load distribution (wind or earthquake) and also locality of the structure. Generally, diagrid structure does not require any interior core as the lateral load is resisted by diagonal members located at the periphery of the structure. From the study, it has been observed that the optimum angle for 40-storey and 60-storey diagrid angle (inclined angle) is in the range of 55° to 65° and 65° to 75°, respectively [1]. Similar report for diagrid structure of 36 storeys under seismic lateral loads shows that efficient diagonal angle for 36 storeys is in the range from 60° to 70° [2]. Nowadays, a flat slab system is been widely adopted in major tall buildings because of its structural efficiency, simple formwork and reinforcing arrangements. It demands less storey height as beams are eliminated. But it can have high lateral drift as the flat slab system is flexible when it is subjected to lateral load (seismic Fig. 1 Swiss Re (London)

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187

Fig. 2 Hearst tower (New York)

Fig. 3 Lotto Super Tower (Korea)

load or wind load). In high seismic zones, the flat slab systems are designed in such a way that the slab column space frame supports gravity loads and also shear wall or other resisting systems provide resistance to lateral load. In this study, analysis of 20-storey diagrid structures with different slab system is studied under seismic lateral load. Lateral load due to earthquake is considered as per Indian Standard IS 1893:2002(Part-I). Two different slab systems, normal slab (i.e. with beams) and flat slab, are considered for diagrid system. These different slab

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Fig. 4 Capital Gate Tower

diagrid systems are designed and analysed in this comparative study. Stiffness-based method is adopted to determine the optimum diagrid angle among five different angles which are as follows: 41°, 50°, 56°, 61° and 64°. Generally, diagrid structure carries both gravity load as well as lateral load, but to increase the efficiency of the structure, four interior columns are introduced which carry gravity load. Element

Label Dimension (mm)

Column

C1

800 × 800 (Where 800 is depth and 800 is width RCC of column)

Material Grade M40

Pipe beam

B1

355.6 × 12 (Where 355.6 is outer diameter and 12 is thickness of the pipe)

STEEL

YST 355

Diagonal pipe D1

500 × 25 (Where 500 is outer diameter and 25 is STEEL thickness of the pipe)

YST 355

Drop panel

–

3000 × 3000 × 250 (Where 3000 is wide length RCC and 250 is depth of drop panel)

M40

Slab

–

200 (where 200 is the depth of slab)

M40

RCC

2 Structural Configuration The 20-storey models have been considered in the study. The plan is square of 20.1 m × 20.1 m. The storey height considered is 3 m. Typical plan, elevation and 3D model are shown in Figs. 5, 6 and 7, respectively. The aspect ratio (H/B) considered is 3.1.

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Fig. 5 a Plan of diagrid structure with conventional slab or normal slab system. b Plan of diagrid structure with flat slab system

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Fig. 6 3D model of diagrid structure

Fig. 7 Different diagrid angles

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Fig. 8 Loading on diagrid structure

3 Loading Considered for Structure Live load considered on floor is 4 kN/m2 and on the roof is 1.5 kN/m2 . Floor finish considered on the floor is 1 kN/m2 . Glass load considered on the periphery of the diagrid is 2 kN/m. The total seismic weight is calculated according to Indian Standard IS 1893:2002 (Part-1). Figure 8 shows loading on diagrid structure. Seismic zone and other factors are mentioned as follows: 1. 2. 3. 4. 5.

Zone: III (IS 1893-Part 1). Zone factor: 0.16 (IS 1893-Part 1). Importance factor: 1.0 (IS 1893-Part 1). Response reduction Factor: 3.0 (IS 1893-Part 1). Soil Type: Medium (IS 1893-Part1).

4 Load Combination Considered Certain load combinations are considered for analysis of diagrid structures which are according to Indian Standard IS 1893:2002 (Part-1) and are listed below: • • • • • • • •

1.5 * (DL + LL) 1.5 * (DL + EQX) 1.5 * (DL − EQX) 1.5 * (DL + EQY) 1.5 * (DL − EQY) 1.2 * (DL + LL + EQX) 1.2 * (DL + LL + EQY) 1.2 * (DL + LL − EQX)

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• 1.2 * (DL + LL − EQY).

5 Modelling Details ETABS v15.2 is used for modelling and analysis of all the structural models presented in this paper. Response spectrum analysis is carried out to study the seismic behaviour of different diagrid models in terms of storey displacement and storey shear.

6 Lateral Deformation Total lateral deformation is a combination of bending deformation due to moments and shears deformation due to lateral shear forces [3]. δb = (H/2B) − 1 δd = (H/B) − 1 where, δb δd H B

bending deformation due to bending. shear deformation due to lateral shear force. the total height of a structure. width of a structure

The δ value increases as the (H/B) ratio increases. With increase in the height of a structure, it becomes more slender and behaves like bending beam.

6.1 Lateral Drift As the lateral load on a structure increases, the maximum inter-storey elastic lateral drift ratio (max/Hi) under working loads has to be limited to H/500 in case of wind load and Hi/250 in case of earthquake load.. For a single storey, the drift limit is to be limited to Hi/400.

6.2 Optimum Uniform Shear Strain As the diagrid structure does not have any vertical member and only diagonal member on the periphery of the structure, it produces higher shear rigidity [4].

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γ = 1/ (1 + δ)α

6.3 Optimum Curvature χ = 2δ/ (H (1 + δ)α) where γ is the optimum uniform shear strain. δ is the optimum lateral deformation. α is the lateral deformation constant.

7 Results and Discussion The results obtained from the analysis are discussed and compared as follows. The results obtained are shown in Figs. 9, 10, 11, 12, 13 and 14. From the Table 1, it is observed that diagrid with flat slab (DFS) has less maximum displacement compared to diagrid with normal slab (DNS) in all the varying angle. From the Table 2, it is observed that diagrid with flat slab (DFS) has slightly less maximum shear force bearing capacity compared to diagrid with normal slab (DNS) in all the varying angles. From the graph in Fig. 11 above, it is observed that 61° diagrid angle in flat slab system is performing better compared to other varying angles in terms of storey displacement. From the result obtained, it can be said that 61° diagrid angle is the

Fig. 9 Maximum displacement of both diagrid with flat slab (DFS) and diagrid with normal slab (DNS)

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Fig. 10 Maximum shear of both diagrid with flat slab (DFS) and diagrid with normal slab (DNS)

Fig. 11 Storey displacement of varying flat slab diagrid

optimum angle among all the varying angles shown in graph in terms of storey displacement. From the graph in Fig. 12, it can be observed that 61° diagrid angle in flat slab system is performing better compared to other varying angles in terms of storey shear. It can be said that 61° diagrid angle is the optimum angle among all the varying angles shown in graph in terms of storey shear. From the graph in Fig. 13 above, it is observed that 61° diagrid angle in normal slab system is performing better compared to other varying angles in terms of storey displacement. From the result obtained, it can be said that 61° diagrid angle is the optimum angle among all the varying angles shown in graph in terms of storey displacement.

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Fig. 12 Storey shear of varying flat slab diagrid

Fig. 13 Storey displacement of varying normal slab (i.e. with beam) diagrid

From the graph in Fig. 14, it is observed that 61° diagrid angle in normal slab system is performing better compared to other varying angles in terms of storey shear. It can be said that 61° diagrid angle is the optimum angle among all the varying angles shown in graph in terms of storey shear.

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Fig. 14 Storey shear of varying normal slab (i.e. with beam) diagrid

Table 1 Maximum displacement value for different diagrid angle structures

Table 2 Maximum shear value for different diagrid angle structures

Diagrid angle (°)

Maximum displacement (mm) DFS

DNS

1°

18.32

18.42

50°

14.46

14.71

56°

11.69

12.10

61°

10.71

10.78

64°

13.46

14.13

Diagrid angle (°)

Maximum shear (KN) DFS

DNS

41°

779.11

788.09

50°

1291.89

1275.43

56°

1390.48

1405.76

61°

1574.03

1587.56

64°

1299.98

1328.06

8 Conclusion Based on the study, some conclusions are drawn which are as follows: • Flat slab diagrid structure performs better compared to normal slab system (i.e. with beam) diagrid both in terms of storey displacement.

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• Normal slab system diagrid performs better compared to flat slab system diagrid both in terms of storey shear because of beams which participate in shear load distribution. • The optimum angle among 41°, 50°, 56°, 61° and 64° is 61° from the results obtained. It can be said that optimum angle for two-storey module diagrid structure in case of both diagrid with flat slab (DFS) and diagrid with conventional or normal slab with beam (DNS) ranges between 56° and 61°. • In this study, DFS performs better compared to DNS as the dead load in the DFS is less as beams are eliminated which results in less storey displacement. • As the displacement depends on the slenderness of the member, the 61° diagrid angle which is less slender among all and near to equilateral performs better than other angled diagrid structures. Acknowledgements I owe a debt of gratitude to the second author and the institute for supporting this work.

References 1. Moona KS (2001) Diagrid structures for complex-shaped tall buildings. Procedia Eng J Struct Eng 14:1343–1350 2. Kim Y-J, Jung I-Y, Kim S-D (136) Cyclic behaviour nodes in diagrid structures. J Eng Struct 136:1111–1122 3. Jani KD, Patel PV (2013) Design of diagrid structural system for high rise steel buildings as per Indian standard. Struct Congress ASCE 2013 4. Montuori GM, Mele E, Brandonisio G, De Luca A (2014) Geometrical patrerns for diagrid buildings: exploring alternative design strategies from the structural point of view. J Eng Struct 71:112–127 5. Kamath K, Hirannaigh S, Kari JC, Noronha B (2016) An analytical study on performance of a diagrid structures using non linear static pushover analysis. J Eng Mech 8:90–92 6. Montuori GM, Mele E, Brandonisio G, De Luca A (2014) Secondary bracing systems for diagrid structures in tall buildings. Eng Struct 75:477–488 7. Moon KS (2011) Diagrid structures for complex-shaped tall buildings. Procedia Eng 14:1343– 1350 8. Sadeghi S, Rofooei FR (2018) Quantification of the seismic performance factors for steel diagrid structures. J Construct Steel Res 146:155–168 9. IS 875-1 (1987) Code of practice for design loads (other than earthquake) for buildings and structures part 1 Dead loads—unit weights of building materials and stored material

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10. IS 875-2 (1987) Code of practice for design loads (other than earthquake) for buildings and structures part 2 imposed loads 11. IS 1893 (Part-1) 2016 Criteria for earthquake resistant design of structures., Part 1 General provisions 12. IS 1161 (2014) Steel tube for structural purposes 13. IS 16700 (2017) Criteria for structural safety of tall building

Graphene Oxide Incorporated Concrete for Rigid Pavement Application P. K. Akarsh and Arun Kumar Bhat

Abstract Nanomaterials are currently one of the trending research topics in material science. Due to a larger surface area, size, aspect ratios, and superior mechanical properties, the nanomaterials can be beneficial in the hydration process and nanopore filling activities. Graphene oxide is one such nanomaterial with one its side in nanoscale, and other two sides are in larger scale. Because of the presence of oxygen functionalities, the graphene oxide can be easily dispersed in the aqueous solution when compared to other nanomaterials. Due to increase in traffic condition and environmental impacts, the pavements are not performing up to the design life. The current investigation is about the use of graphene oxide as cement additive and checking its suitability for the pavement application. In this study, polycarboxylatebased superplasticizer is used to improve the adhesion and dispersion property of the graphene oxide. The graphene oxide is added in the dosages like 0.05, 0.1, 0.15, and 0.2% by weight of cement. Number of tests has been conducted to analyze the impact of additive. The workability of graphene oxide concrete gradually decreases with the increase in its dosage, and the loss of workability is not so significant. The mechanical properties of concrete like compressive, flexural, and tensile strength are greatly increased with the addition of 0.15% graphene oxide, which is found out to be optimum dosage. The percentage increase in flexural strength is more than the percentage increase in compressive strength at 7 and 28 days. The percentage improvement in early strength is more when compared to later percentage improvement. SEM images show, with the presence of graphene oxide, there is a formation of dense microstructure. The overall test result shows that graphene oxide can be used in pavement quality concrete.

P. K. Akarsh (B) Construction Technology, NMAM Institute of Technology, Nitte, Karkala, Udupi, Karnataka 574110, India e-mail: [email protected] A. K. Bhat Department of Civil Engineering, NMAM Institute of Technology, Nitte, Karkala, Udupi, Karnataka 574110, India e-mail: [email protected] © Springer Nature Singapore Pte Ltd. 2021 M. C. Narasimhan et al. (eds.), Trends in Civil Engineering and Challenges for Sustainability, Lecture Notes in Civil Engineering 99, https://doi.org/10.1007/978-981-15-6828-2_16

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P. K. Akarsh and A. K. Bhat

Keywords Nanomaterials · Graphene · Graphene oxide · Oxygen functionalities · Dispersion properties · Pavements

1 Introduction 1.1 General In the developing countries like India, the concrete becomes one of the important materials for the development of infrastructures, buildings, pavements, etc. Normal concrete consists of cement, aggregates, and water mixed in suitable proportions. Nowadays, due to the advancement in the concrete technology, the preference for special concrete is given consideration. It is well-known fact that concrete is good in resisting compressive stresses and weak in defending tensile stresses due to its brittleness. This weakness of cement and its components is being researched on to find a possible solution of overcoming this. With the introduction of fiber-reinforced concrete (FRC), the crack propagation problem is minimized; ductility and toughness can be maximized. But it fails to stop the micro-crack initiation. And moreover, fibers have lesser surface area for hydration process [1, 2]. In order to overcome all these aspects, the use of nanomaterials in concrete is one of the solutions due to their superior mechanical, chemical properties [3], and specific surface area. Nanotechnology application to concrete presents an innovative approach to improve concrete properties based on the ability to manipulate the cementitious material at an atomic scale. The reactions taking place in the cement matrix depend on the smallest pores to the climatic condition. Concrete has pores ranging from nano (10−9 m) to micro (10−6 m) scale. These pores can be minimized by good compaction. In spite of good compaction, some smaller pores will remain in the cement matrix. The strength of concrete depends on the formation of calcium silicate hydrates (C-S-H) products, and hydration products are dependent on the pores at nanolevel and microlevel. Filling these pores with inert or reactive material can enhance the strength, and durability properties reduce the formation of cracks. When microlevel pozzolanic materials like silica fumes, GGBS, fly ashes are used, it is only possible to fill micropores. The nanolevel pores can be filled with the help of these nanomaterials. Nanomaterials have remarkable surface area [4], and sizes of various materials used in concrete are compared with their surface area as shown in Fig. 1. As the size of the material decreases, the surface area for the reaction increases. Due to this hydration reaction, calcium hydroxide converts into C-S-H and denser structure will be formed by filling the pores in the transition zone of cement. The usage of nanomaterial is well accomplished in the field of material science, biotechnology, and electronics. Earlier years, the use of nanomaterial in construction industry is limited due to the lack of information regarding the performance of material when it is incorporated with cementitious materials, high cost and the usage of material. In the recent years, many researches are happening in this field to check the suitability of material. The nanofiller group consists of nanoparticle like n-SiO2 ,

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Fig. 1 Particle size and specific surface area of materials used in concrete [4]

nanotubes like carbon nanotubes (CNTs), and nanoplates like graphene oxide. The various applications and effects of nanomaterials in concrete are briefed in upcoming paragraphs. The addition of nanomaterials into the cement matrix alters the fresh and hardened properties. Ye et al. [5] and Senff et al. [6] investigated the effect of nano-silica (nSiO2 ) and silica fume in cement paste, the setting time, segregation, and bleeding is greatly reduced when n-SiO2 is used. With the inclusion of n-SiO2, the fluidity of concrete mix reduces and densifies the microstructure by filling microvoids in the transition zone [7, 8]. Gonzalez et al. [9] examined n-SiO2 for the application of rigid pavements and compressive strength, aggregate paste bond, and abrasion resistance properties were greatly improved with lesser dosages due to pozzolanic activities. Titanium dioxide nanoparticles (n-TiO2 ) are well known for its photocatalytic selfcleaning properties [10, 11]. Melo and Trichês [12] used n-TiO2 in photocatalytic concrete for the application on road surfaces, enhanced the mechanical strength, improved hydration of cement, and reduced modulus of elasticity. The use of nTiO2 in concrete mixtures reduces the water absorption percentage and capillary absorption due to its pore-filling capabilities [13]. The abrasion resistance of concrete containing n-TiO2 is found to better for the same amount of n-SiO2 [14]. The flexural fatigue resistance of concrete containing n-TiO2 gave good result when compared to commonly using polypropylene fibers [15]. Nazari et al. [16] observed mechanical properties improvement with 1.0% nano-alumina (n-Al2 O3 ) replacement of cement.

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Carbon inclusive nanomaterials are mostly of graphene derivative. Graphene is a two-dimensional one atom thick layer of carbon arranged in the form of hexagonal honeycomb lattice with one atom forming each lattice. Basically, graphene is a functional unit of graphite. In graphene, carbon atoms are packed in a regular sp2-bonded hexagonal structure, with a C–C bond length of 142 nm. [17] Carbon nanotubes (CNTs) are graphene sheets rolled in the form of tube-like structure. Apart from mechanical properties improvement, CNTs when dispersed uniformly throughout the cement matrix, one can see crack bridging or micro-crack linking at the initial phase of its proliferation due to their extremely high aspect ratio [18, 19]. Loh and Gonzalez [20] used multi-walled carbon nanotubes (MWCNTs) for investing the damage sensing capabilities in the cement matrix for different compressive strains as an application of pavement because of its electro-conductive properties. Zuo et al. [21] suggested to apply the CNTs in traffic pavements to monitor traffic, vehicle speed, temperature sensing due to its electrical sensing properties. In spite of many advantages, possessed by nanomaterials like n-SiO2 , CNTs, and graphene, they tend to form agglomerates when added to water or any solvent due to strong van der Waals force [22]. This agglomeration in concrete leads to the formation of voids or unreacted pockets, or they are not able to react with cement matrix [23]. Thus, the stress concentrated in this zone leads to rupture or it is not distributed uniformly. The dispersion is possible by ultrasonication or by surfactants. But in case of graphene oxide, this problem of dispersion is less due to oxygen functionalities. This is one of the major advantages for using graphene oxide, and moreover, this material is comparatively less researched one than other nanomaterials as for pavement application.

1.2 Graphene Oxide Incorporated Cement Matrix/Concrete Graphene oxide (GO) is single-layered nanomaterial consisting of oxygenated graphene sheets, carrying hydroxyl (OH) and epoxy (–O–) on their basal plane and having carboxyl (COOH), and carbonyl (C= O) on the sheet edge shown in Fig. 2 [24]. Graphene oxide has a tensile strength of 130 Mpa and modulus of elasticity of 23–42 GPa [25, 26]. During the oxidation of graphite sheets, the oxygen functionalities are introduced and reduced the bond strength between graphite oxide sheets. This makes the material hydrophilic [27]. The presence of these active groups alters the van der Waals force between graphene oxide particles and helps in dispersion and reactivity [28]. Addition of GO to cement can enhance the mechanical properties. Kang et al. [29] got a positive result at relatively lesser percentages of GO, i.e., increase in compressive strength by 32% (0.05% GO), bending strength by 20% (0.1% GO), and tensile strength by 26% (0.01% GO) than OPC. Wang et al. [30] reported that there was an increase in flexural strength by 27% and compressive strength by 16.4% for the optimal dosage of 0.08% in the cement mortar. With lesser dosage of GO (0.04% by weight), mechanical strength can be enhanced when compared to n-Al2 O3 (2% by weight) in cement matrix [31]. According to three-dimensional network structure

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Fig. 2 Structure of graphene and graphene oxide [32]

of GONS modified cement system proposed by Wang et al. [28], the enhancement in strength is may be due to the reaction between COOH present in sheet edges of GONS and Ca(OH)2 of hydration product. The 3-D product formed acts as nucleation site for C-S-H gel and crystals for hydration reaction. Addition of GO can fill the minute pores, as a proof, pore structure analysis done by the Gong et al. [33] found that there was decrease in total porosity by 13.5%, capillary pores by 27.7% and increase in gel pores by more than 100% in cement paste. More C-S-H products can be seen if there is increase in gel pores. Similarly, Roy et al. [2] used GONS dispersion along with silica fumes and metakaolin in mortar for checking water absorption and sorptivity test. There was a modification in the shape of cement hydration products due to the presence of GONSs found in FE-SEM analysis, and the crack-bridging mechanisms found in CNTs were difficult to find in GO due to their low volume and planar geometry [34]. Graphene oxide nanosheets undergo rapid deoxygenation in strong alkali solutions even at moderate temperatures. Therefore, the presence of Ca(OH)2 in cement pores had bad effect on the stability of GONSs [35]. The use of superplasticizer could counteract the effect of Ca(OH)2 on GONSs [36]. Polycarboxylate (PC)-based superplasticizers are more compatible with the carbon inclusive nanomaterials and helps in dispersion properties [37]. Zhao et al. [38] investigated the different superplasticizer like lignosulfonate, polycondensate of β-naphthalene lignosulfonate formaldehyde, and polycarboxylate with the GO compatibility and the usage of PC resulted them proper dispersion in cement pore solution. The functional groups of PC reduce the available calcium ions in cementitious environment which is available for interaction

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with the GO and preventing the GO agglomeration. Secondly, PC-based superplasticizer uses strong steric hindrance effect to push the cement particles. The steric repulsive forces caused by polycarboxylate have COOH as its functional group. The COOH group attaches to GO and reduces the van der Waals force between them. This creates a repulsive force between GO sheets and helps them to disperse properly. It also increases energy required to pullout the GO from cement matrix [39]. When nanomaterials like graphene oxide are used as pavement materials, one can expect the changes in mechanical and durability properties of concrete by suppressing the negative effects of environment and heavy load traffic condition. Application of it can modify the microtexture of concrete pavement and thereby macrotexture. A very few researches have done with graphene oxide as pavement material because the use of nanomaterial in the construction field is still in dormant stage. The current investigation includes testing the various properties of graphene oxide incorporated concrete like its compressive strength, flexural strength, split tensile strength, characterization, and checking its suitability for the application of pavement.

2 Experimental Investigation 2.1 Materials In the present investigation, the fresh OPC-53 grade is used, conforming to the requirements of Indian Standard (IS): 12269-2013. It was supplied from the reputed cement producing company practicing advanced quality production and guaranteed chemical composition of cement. The physical test results are shown in Table 1. Aggregates are procured from M/s Oriental Granites and Crushers, Karkala Taluk, Udupi. Aggregates used are free from organic impurities. Coarse aggregates used are natural crushed granite aggregates with particle passing 20 mm and retained on 4.75 mm (maximum 20 mm) as per IS:383-2016. Gradation values of crushed aggregates are shown in Chart 1 Manufactured sand was used as a fine aggregate (MTable 1 Physical properties of cement Test

Results

Limits as per IS 12269-2013

Reference of test method

Fineness modulus

Less than 1%

Max 10%

IS 4031(PI)-1996

Soundness by Le-Chatelier’s apparatus

Less than 1%

Max 10 mm

IS 4031(P III)-1988

Standard consistency

32%

–

IS 4031 (PIV)-1988

Initial setting time

70 min

Min 30 min

IS 4031 (Part V)-1988

Final setting time

330 min

Max 600 min

IS 4031(Part V)-1988

Specific gravity by Le Chatelier’s flask

3.15

–

IS 4031 (Part XI)-1988

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Chart 1 Gradation test result of crushed coarse aggregates

sand) due to the non-availability of natural river sand. It was conformed to the zone II of IS: 383-2016 with fineness modulus of 2.5. Gradation test values are shown in Chart 2. The physical test limit values were taken from Indian Road Congress (IRC):15-2011 and Ministry of Road Transport and Highways (MORTH), and the physical test results were in limits shown in Tables 2 and 3 for coarse aggregate and M-sand, respectively. For better dispersion of GO and improve the cohesiveness of the concrete mix, a high range of polycarboxylate-based water reducer is used. The superplasticizer called Auramix 400 PQC was procured from Fosroc Chemicals India Pvt. Ltd. The property of Auramix 400 is conformed to IS: 9103-1999. Graphene oxide was procured from Ad-nano Technologies Pvt. Ltd. It was produced by modified Hummer’s method by the company itself, like in the form of blackish powder. For the present investigation, the aqueous dispersion of graphene oxide was prepared in magnetic stirrer equipment using the guidelines of company. Graphene oxide used has a surface area of 200 m2 /gm with the smallest dimension of 1-4 nm. The potable tap water is used for preparing the GO solution, concrete mixes and for the curing of specimens.

2.2 Mix Proportion The mix design for pavement quality concrete (PQC) was done based on the procedure given in IRC:44-2008. The maximum cement quantity for PQC is restricted to 425 kg/m3 as per IRC:15-2015, and the same is adopted for current study with

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Chart 2 Gradation test result of M-sand Table 2 Quality test of crushed coarse aggregates

S. No.

Test

Results

Test method

1

Combined index

21.4%

IS 2386 (PI)-1963

2

Specific Gravity

2.69

IS 2386 (PIII)-1963

3

Water absorption

0.5%

4

Aggregate crushing value

24%

5

Aggregate impact value

16.7%

6

Los angeles abrasion value

22%

IS 2386 (PIV)-1963

Table 3 Physical properties of M-sand S. No.

Test

Results

Limits

Reference code

Test method

1

Particle passing 75 μ

2.6%

Max 15%

IRC 15 2011

IS 2386 (PI)- 1963

2

Water absorption

1.2%

Max 2%

IRC 15 2011

IS 2386 (PIII)-1963

3

Specific gravity

2.62

–

–

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w/c ratio of 0.35 (less than 0.45). The coarse aggregate to fine aggregate ratio of 0.64:0.36 was maintained. The mixes are designed in such a way that, they should attain a slump of 30-50 mm. The superplasticizer dosage of 0.6% (by weight of binder content) is used to maintain the designated slump value, and the same can sustain the water required for water absorption of aggregate. The quantity of cement, aggregates, water, and superplasticizer dosage is kept constant for whole investigation. The dosage of graphene oxide is varied in form of 0.05, 0.1, 0.15, and 0.2% by weight of binder content. Graphene oxide aqueous solution is prepared in the laboratory with the help of magnetic stirrer equipment. The magnetic stirrer has stir bars and rotates at 6001000 rpm by the application of magnetic field. To improve the adhesion property of graphene oxide, the superplasticizer is mixed with water initially in stirring equipment and calculated quantity of graphene oxide is added slowly to the rotating mix. In the first few minutes, the rpm maintained was less and after 4-5 min, the rpm is set to maximum for 7-10 min. A black solution containing graphene oxide along with the superplasticizer shown in Fig. 3 obtained is added to the concrete mix at the end. The solution water is subtracted from total quantity water. The mixed name for conventional concrete is given as CG0. The mix name for 0.05, 0.1, 0.15, and 0.2% GO is given as CG1, CG2, CG3, and CG4, respectively. Mix proportions of nanomodified concrete are shown in Table 4. Fig. 3 The 0.5% solution of GO

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Table 4 Mix proportion used for testing the specimens Mix name

Addition of GO % by weight of binder

OPC in kg/m3

Water in kg/m3

Crushed aggregate in kg/m3

M-sand in kg/m3

Auramix 400 in kg/m3

CG0

0

425

148.5

1190

670

2.125

CG1

0.05

425

148.5

1190

670

2.125

CG2

0.1

425

148.5

1190

670

2.125

CG3

0.15

425

148.5

1190

670

2.125

CG4

0.2

425

148.5

1190

670

2.125

2.3 Tests and Specimen Details After dry mixing of aggregates and binder, water apart from GO solution is added, mixed for few minutes. Later GO solution containing superplasticizer is added and mixed until cohesive mix is obtained. After proper mixing, the consistency of the mix is checked by slump test as per IS: 1199-1959. A vibrating table is used to compact the prepared concrete after its addition to respective molds and vibrated for few seconds. For checking compressive strength of the obtained mix, cubes of 100 mm × 100 mm × 100 mm were cast. The essential parameter for pavement is its flexural strength. To find the flexural strength of the mixes, 100 mm × 100 mm × 500 mm prisms were cast. The cylinders of 150 mm × 300 mm were cast for split tensile test. For each mix, a minimum of three samples was cast. The casted specimens are undisturbed for 22 ± 2 h and de-molded. The specimens casted are allowed for water immersion curing at room temperature (27 ± 3 °C) and tested at 7 days and 28 days. The cubes of 100 mm × 100 mm × 100 mm were used to find saturated water absorption and volume of permeable voids at 28 days. In order to analyze the surface morphology of graphene oxide and concrete specimens, the scanning electron microscope (SEM) images are used. In order to take the images, an analytical scanning electron microscope called JEOL JSM-6380LA is used. Before the specimen is scanned at an accelerating voltage of 20 kV, gold coating is done with the help of JFC 1600 auto fine coater for 110 s. Coating is necessary as the specimens are non-conductive in nature. Figure 4a shows the surface morphology of graphene oxide as obtained from the seller and scanned at the scale of 1 μm. It can be seen that, graphene oxide is in the form of thin sheet-like texture with rough surface. The material is haphazardly arranged and sheets connected with each other to shape a disordered piece of solid. The procured nanomaterial is scanned in X-ray diffractometer at a scanning rate of 2°/min in 2θ range of 5-60° subjected to Cu-Kα radiations. Figure 4b shows the XRD of procured GO nanosheets. An intense peak at 2θ angle of 11.56° is observed with lattice spacing of 0.806 nm.

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Fig. 4 a SEM of graphene oxide nanosheets. b XRD of procured graphene oxide nanosheets

3 Results and Discussion 3.1 Fresh Properties Test The workability of the concrete is very important, when it comes for placing. After proper mixing, the mixes are subjected to slump cone test. All the mixes achieved the designated slump value. Slump test results are shown in Table 5. For conventional one, the superplasticizer dosage is tested to attain a slump value of 50 mm, and the same dosage is used to check other mixes consistency. When aqueous dispersion of graphene oxide solution is added to the mix, the slump value started to decrease gradually and the stiffer mixes are observed with increase in GO content. There was a decrease in slump by 10%, 20%, and 30% for CG2, CG3, and CG4, respectively, than the conventional one. The larger surfaced graphene oxide requires more water to wet its surface at given water to binder ratio and superplasticizer dosage. This can be adjusted by additional polycarboxylate-based superplasticizer [40]. However, the slump loss showed in Table 5 is not so significant decrease. Bleeding and segregation were not observed in GO containing mixes. Table 5 Consistency check by slump test

Mix name

Slump value in mm

% variation from CC specimen

CG0

50

0

CG1

48

−4

CG2

45

−10

CG3

40

−20

CG4

35

−30

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3.2 Compressive Test After 7 days and 28 days of curing the specimens, the cubes are tested for compressive strength in accordance with IS: 516-1959. Each mix containing three samples was placed opposite to their cast side and tested at the rate of loading of 14 N/mm2 /min. The failure load is noted, and the converted values are given in Chart 3. With the addition of aqueous dispersion of GO solution, the compressive strength of concrete increased gradually. All the specimens show higher compressive strength than the CG0 specimen at 7 and 28 days. The compressive strength of CG1 is slightly higher than the CG0 specimen. The reason may be the insufficient dosage of GO available for the reaction. The CG3 specimen shows greater strength than all the specimens tested. In CG3 specimen, the GO solution is well-acted (dispersed) and the increase in strength shows that there may be well-established bond between GO and paste. The compressive strength increased up to CG3 specimen and at CG4, the graph followed downward trend at both 7 and 28 days. This is may be, at higher dosages, the concrete mix containing GO solution requires high-speed mixer for their well dispersion and at higher dosages, the possibility of forming clusters/agglomerates is predominant. The agglomerates are formed due to the inter-layer van der Waals forces which disturbs the dispersion of GO in the matrix [41]. So clusters result in non-homogenous distribution of hydrates, ultimately there will be the formation of weaker sections [42].

Chart 3 Compressive strength test result

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The specimens CG1, CG2, CG3, and CG4 show an increase of 6.17%, 12.27%, 19%, and 14.4%, respectively, at 7 days than CG0 specimen and the same specimens showed an increase of 2.15%, 6.3%, 12.72%, and 9.9%, respectively, at 28 days compared with CG0 specimen. The percentage change implies that, the gain of strength was more predominant at first 7 days when compared to 28 days. This shows at early stages of concrete, and graphene oxide forms a favorable platform by providing nucleation sites for hydration reaction. All the mixes containing GO attains sufficient strength at 28 days of curing which is necessary for the application of pavements. All the mixes attained strength more than 50 Mpa which is very sufficient, and it also satisfies the minimum strength requirement of M40 for national/state highways as per IRC: 58-2015. The early high strength concrete gives an advantage for opening of pavement for the usage of traffic.

3.3 Static Flexural Test As flexural stresses are predominant in the pavements, the test for flexure is compulsory. Static flexural test has been conducted for all the samples as per IS: 516-1959 by symmetrical two-point loading method. The prism specimens are placed on supports with 400 mm apart as shown in Fig. 5 and tested at the rate of loading of 1.8 KN/min. The specimens are tested in the partially damp conditions at 7and 28 days. The breaking load in KN is noted, and calculated flexural strength in MPa for various mixes is presented in Chart 4. With the addition of graphene oxide solution, the flexural strength of concrete increased. All the specimens containing GO shows higher flexural strength than the CG0 specimen at 7 and 28 days. The strength increase pattern is similar to that of compressive strength. CG3 specimen shows the highest flexural strength at both 7and 28 days when compared to all the mixes. Up to CG3 specimen, the graph

Fig. 5 Prisms placed in universal testing machine to find breaking load

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Chart 4 Flexural strength test results

shows positive trend and at CG4, the flexural strength drops. The drop may be due to the improper dispersion and formation of agglomerates. As mentioned earlier, these agglomerates, instead of filling the nano-voids, they became the pocket of weak zones. At 7 days, the percentage increase in flexural strength shown by specimen CG1, CG2, CG3, and CG4 are 7.22%, 14.23%, 19%, and 16.34%, respectively. At 28 days, the specimen shows an increase by 3.82%, 10%, 14.5%, and 12.36%, respectively. The increase in flexural strength percentage is more when compared with increase in compressive strength percentage which is very essential for pavement. All the mixes attained a flexural strength greater than 4.5 MPa (minimum flexural strength requirement as per IRC: 15-2011 standards).

3.4 Split Tensile Test The split tensile test is conducted on cylindrical specimens after 7 and 28 days of curing. The test is conducted in accordance with the IS: 5816-1999. The cylindrical specimens are placed perpendicular to the testing machine, and load is applied at the rate of 1.4–2.1 N/mm2 /min as shown in Fig. 6. The load at which the specimen fails is noted, and the results are given in Chart 5. It is evidenced that the incorporation of GO increases the tensile properties of concrete. All the mixes show greater tensile strength than the control mix at 7 and 28 days. The tensile strength of CG3 specimen shows a maximum improvement of 13.68% than the CG0 specimen at 28 days. Beyond CG3 specimen, the graph

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Fig. 6 Cylindrical specimens for split tensile test

Chart 5 Split tensile test results

follows negative trend. At higher dosages, it requires more water to wet the surface and consumes the water required for hydration process. When tensile stresses are applied, GO shows breakout mechanism and not the pull out mechanisms seen in fibers and CNTs [39]. Whichever the nanomaterial it may be, in order to extract its full properties, the proper mixing techniques and dispersion techniques are very essential

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3.5 Water Absorption Test and Volume of Permeable Voids The saturated water absorption (SWA) and volume of permeable voids (VPV) are conducted based on the procedure given in ASTM C642-13. A set of three (100 × 100 × 100)mm cubes is used. After 28 days of curing, the test is conducted. The results of SWA and VPV test are shown in Charts 6 and 7, respectively. The strength and durability properties of concrete are dependent on the water absorption and permeable voids properties. The water absorption by a cube depends on the pores present inside the concrete. The CG3 specimen shows the least water absorption % and VPV% when compared to other specimen. This is maybe due to the presence of nanoscale graphene oxide. So the voids may fill in nano- and microscales. Automatically, the water absorption and VPV will decrease and protection against the ingress of other chemical may increase. The CG4 shows lesser value than the CG3 specimen. This may be due to improper dispersion of graphene oxide, and cluster creates larger voids. Thus, larger voids will result in larger water absorption percentages and VPV%. The main advantage of the GONS is the presence of oxygen functionalities. Along with that, if the usage of any dispersion techniques is adopted, one can expect better results from the nanomaterial.

Chart 6 Saturated water absorption test results

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Chart 7 Volume of permeable voids% of different specimens

3.6 SEM Analysis of Selected Specimens The SEM image of fracture surface of CG0 concrete specimen (without GO) after 28 days curing is shown in Fig. 7. Basically, Fig. 7a shows the fundamental hydration products, such as needle-like ettringite (AFt phases), laminated calcium hydroxide (Ca(OH)2 ), and fibrous or hairy calcium silicate hydrates (C-S-H), inter-transition zone (ITZ) between cement hydrates and aggregates at the scale of 10 μm. Figure 7b clearly shows the CSH and AFt phases are seen at scale of 1 μm. The pores are more visible in the CG0 specimen. Figure 8 shows the SEM image of fracture portion of GG3 specimen (with 0.15%

Fig. 7 a SEM image of hydration products, inter-transition zone present in CG0 specimen. b Calcium silicate hydrates and AFt phases in CG0 specimen

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Fig. 8 a Hydration products appear like dense sponge-like structure in CG3 specimen. b Thin sheets resembling like GO sheets along with the calcium hydroxide

GO) after 28 days curing. Figure 8a shows aggregate covered with the dense hydration products, and the hydration products appear to be quietly undistinguished due to densely formed microstructure scanned at scale of 10 μm. Some of the cracks are also visible in image, showing lot of stress is taken by the specimen. The enlarged view is shown in Fig. 8b C-S-H; the most desirable product of cement hydration appears like dense sponge at the scale of 5 μm. The dense microstructure may be due to the well bonding between GO and cement products. The dense microstructure may be due to well bonding between GO and cement products. Compare to CG0 specimen, the CG3 specimen shows less visible pores due to the pore filling activity of GO nanosheets. For the current investigation, the usage of GO is very less, it is very difficult to find the GO sheets in the specimen (either, the hydration product may cover the GO or due to its planar geometry, difficult for identification). Comparing Figs. 7 and 8, the shape of hydration products has changed. The well-dispersed GO and dense microstructure may be the reason for high flexural strength shown by CG3 specimen. The stronger bonding between the GO sheets and cement hydration products and improvement in its mechanical properties may also due to the nucleation of C-S-H by GO sheets. The nucleation of C-S-H also accelerates the hydration process [39]. Thus, the addition of GO can enhance the early strength due to its larger surface area and nucleation of hydration products.

4 Conclusion 1. When graphene oxide is added to the mix, the workability of the mix gradually decreased. The loss of workability can be maintained with the use of superplasticizer. 2. With the addition of aqueous dispersion of GO, there was an increase in compressive strength. The specimen CG3 with GO content 0.15% by weight shows the highest compressive strength than all mixes tried. At CG4 specimen, the

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4. 5. 6. 7.

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compressive strength drops. The possible reason may be the improper dispersion of GO and inadequate adhesion with cement. The compressive strength of CG3 specimen shows an increase of 12.72% than CG0 specimen at 28 days. For the application of pavements, sufficient amount of flexural strength is developed with nanomodified concrete. The CG3specimen shows an increase of 14.5% than CG0 specimen at 28 days. GO incorporated concrete is good at resisting the flexural stresses than the compressive stress. The tensile properties are also greatly improved. With 0.15% of GO, the tensile strength increased by 13.68% at 28 days than the control mix. The early gain in strength shown by GO incorporated concrete is more than the later gain in strength. The nano-filling effect shown by graphene oxide (0.15% by weight) may be the reason for least saturated water absorption % and volume of permeable voids %. SEM images of hardened concrete indicates that, the use of GO can create dense microstructure and also reduces the pores in the inter-transition zone.

5 Recommendations In order to extract the full potential of any nanomaterial, the consideration should be given to dispersion property and bonding between the cement hydration products. Formation of agglomerates can create the voids. Hence, proper dispersion and mixing techniques must be adopted. The use of it may reduce the quantity of material required and thickness of slab. In spite of this, the use of nanomaterials as additive in pavement concrete can increase the material’s direct cost. Life cycle analysis method must be used to evaluate the economic benefit of this technology. But this is beyond our current investigation scope.

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Prediction of Effect of Geometrical Parameters in Trough Shape Folded Plate Roof Using ANN Modeling Bhagwan Girish Shanbhag and Y. R. Suresh

Abstract Finite element method is a numerical technique used to obtain approximate solutions to the problems with boundary values. It is simply a technique used in solving problems which have partial differential equations and boundary conditions. This method gives approximate results at each and every discrete number of points over the domain. A consistent model is to be developed for easier, faster and less expensive structural development. In this regard, artificial neural network can have high possibilities as these networks are universal approximators that can carry out any uninterrupted mapping and can provide general mechanisms for building models from data whose input–output relationship is highly nonlinear. In this paper, the behavior of trough shape folded plate roof is studied in terms of displacement and stresses for different boundary conditions using the software SAP-2000 (v-20) by varying geometrical parameters (thickness, bay width and height of FPR) and to extract the information on the importance of the input parameter on the prediction of output results using artificial neural network model. Keywords Artificial neural network · Finite element analysis · Folded plate roof · Garson algorithm

1 Introduction Artificial neural networks are computational systems inspired from the biological brain in their structure, data processing restoring method and learning ability. Specifically, a neural network is defined as a largely parallel disturbed processor with a natural propensity to store experimental knowledge and makes it available for future use in two ways—(a) The network acquires knowledge from a learning process and B. G. Shanbhag (B) · Y. R. Suresh Department of Civil Engineering, NMAM Institute of Technology, Nitte, Karkala, Udupi, Karnataka 574110, India e-mail: [email protected] Y. R. Suresh e-mail: [email protected] © Springer Nature Singapore Pte Ltd. 2021 M. C. Narasimhan et al. (eds.), Trends in Civil Engineering and Challenges for Sustainability, Lecture Notes in Civil Engineering 99, https://doi.org/10.1007/978-981-15-6828-2_17

221

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(b) the strengths of inter neuron connection called as synaptic weights are used to store the knowledge. Folded plate structures are best defined as flat plate or slab assemblies, inclined in various directions and attached along their longitudinal edges. The structural system is thus able to carry loads along mutual edges without the need for additional supporting beams. Such structures have been described by other names, including hipped plates, prismatic shells and prismatic pitched slabs. Typically, modern folded plates structures are made of reinforced concrete cast in situ or precast or steel plate. Various types of folded plate roofs include V type, trapezoidal type, trough type, north light type, etc. Folded plate roofs have been used for considerable advantage due to their rigidity and strength in situations where large areas need to be covered free from internal columns and other obstructions. For aircraft hangars, with spans of up to 160 ft. on both side of a centrally anchor wall, a folded plate cantilever system is used very successfully.

1.1 Related Works Chauhan [1] developed computer programs in MATLAB based on Simpson’s method to analyze different types of folded plate roofs like V, trough type and North light type of folded plate roofs in order to avoid conventional methods which are cumbersome and time consuming [1]. Desai et al. [2] used the concept of folding, as seen in nature and origami, to increase load bearing capacity; folded plates are used as roofing structure for long span. Glass, timber and R.C.C. are the material used for folded plate structure [2]. Chacko et al. [3] made parametric study on transverse and longitudinal moment of trough type of folded plate roofs using ANSYS. The results of the study gave insight to the range of magnitude of various parameters to be considered for the optimum performance of plate [3]. Elkady and Hasan [4] studied the impact of various factors like stiffness of end diaphragms, intermediate beam stiffness, folded plate rise and folded plate thickness on static and dynamic behavior of quadratic folded plate (QFP) slabs by performing linear static analysis based on finite element modeling [4]. Lakshmy and Bhavikatti [5] studied the optimization of simply supported symmetrical trough-type folded plate roofs using improved move-limit method of sequential linear programming and sequential unconstrained minimization technique [5].

1.2 Methodology In the present study, analysis is done for trough shape folded roof (Ref. Fig. 1) square in plan by changing geometry and boundary conditions. Roofs are supported on all four ends with fixed and hinge boundary conditions. The variation of displacement and percentage reduction in displacement is studied (Table 1).

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Fig. 1 Typical cross section of trough shape FPR; b = bay width; H = height of FPR; a = width of one fold;  = inclination to horizontal

Table 1 Parameters considered for the study Plan size

20 × 20

Span

20

m

Height

L/15, L/20 and L/25

m

Plate thickness

75–130

mm

Boundary conditions

Fixed and hinged

Live Load

0.8

kN/m2

Compressive strength of concrete [6]

25

N/mm2

Density

25

kN/m3

Young’s modulus

25

GPa

Poison’s ratio

0.2

Mesh size

0.2 × 0.2

m2

m2

1.3 Selection of Geometries According to IS: 2210-1988 [7], the height of folded plate roof should be L/15. Hence, heights of L/15, L/20 and L/25 are selected. By using the below formula, the possible number of bay can be calculated for any height and for any plan dimension.  = tan−1 (H/a) = 30◦ to 60◦

(1)

where  = inclination to horizontal; H = L/15 to L/25; a = b/5 (Fig. 1); L = span; b = bay width. By trial and error procedure, the number of bays is assumed for a fixed total width “B” and assumed height “H.” Corresponding value of “a” is calculated from the obtained bay width “b” and substituted in Eq. (1) for the constant span. Table 2 shows the possible number of bays for various heights. All the number of bay is selected so that the roof structure is symmetric (Fig. 2).

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Table 2 Geometrical parameter for different height n

H = 1.33 m b

2

b

H = 0.8 m 

b



33.62

–

–

–

–

3

6.67

45

6.67

36.94

6.67

31.03

4

5

53.06

5

45

5

38.66

4

5

10

H = 1.00 m 

58.98

4

51.34

4

45

6

–

–

3.33

56.17

3.33

50.05

7

–

–

–

–

2.86

54.53

8

–

–

–

–

2.5

57.99

H = Height of FPR; n = number of bay;  = inclination to horizontal (in degrees)

Fig. 2 Cross section of trough shape folded plate roof with various number of bay; n = number of bay

1.4 Finite Element Analysis Using the SAP 2000 (version 20) software, linear static analysis is carried out and 336 models are analyzed for dead load and live load combination [8]. The quadrilateral element with four node and six degrees of freedom for each node is considered that has both bending and membrane capabilities.

Prediction of Effect of Geometrical Parameters in Trough …

225

Fig. 3 Artificial neural network modeling procedure in WEKA 3.8

1.5 ANN Modeling Around 166 data sets from each parameter are considered to develop the respective ANN model. These data sets are divided for training and validation process. ANN models are developed using available software WEKA 3.8 by defining input and output parameters. Multilayer perceptron neural network is used for the optimal performance of network model (Fig. 3).

1.6 Statistical Measures [9] Coefficient of determination, COD = R2 , where R is the correlation coefficient given by

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    (OP O ) ∗ (OP P ) − (OP O ) ∗ (OP P ) R =         N (OP)2O − (OP)2O ∗ N (OP)2P − (OP)2P N

Coefficient of efficiency, 

 {(OP) O − (OP) P }2

2 ,  (OP) O − (OP O

COE = 1 − Root mean square error, RMSE =

 ((OP) O − (OP) P )2 n

where (OP)  O = observed output, (OP) P = predicted output, n = number of observed output, OP O = mean of the observed output.

1.7 Garson’s Algorithm Garson’s algorithm [10, 11] determines the relative significance of each input parameter used to model the system outcome. This method uses the weights of connection obtained from the artificial neural network. The calculation process required for the Garson’s algorithm with three input neurons can be summarized as follows. Referring to Fig. 4, 1, 2, 3 are the three input neurons; A, B are two hidden neurons, and

Fig. 4 Artificial neural network structure for the illustration of Garson algorithm

Prediction of Effect of Geometrical Parameters in Trough …

227

O is the output neuron. The hidden layer is selected such that the values of COD and COE are maximum and the value of RMSE is minimum. • Input-hidden-output neuron connection weights, i.e., referring to Fig. 4, W A1… , W B1… , W OA, W OB are tabulated • Contribution of input neuron to the output through each hidden neuron, i.e., C A1 = W A1 × W OA • Relative contribution of input neuron given by rA1 = I CA1 I /(I CA1 I + I CA2 I + I CA3 I ), rB1,rC1, . . . • Sum of input neuron contributions, S 1 = r A1 + r B1 + … • Relative importance of each input parameter is calculated by

R I1 = (S1 /(S1 + S2 + S3 )) × 100

2 Results and Discussion 2.1 Analysis of Folded Plate Roof Linear static analysis had been carried out for a trough-type folded plate roof of plan 20 m × 20 m. Around 336 models were analyzed under various height, thickness and bays for both the boundary conditions. The following figures show the displacement variation with thickness for different height for hinged and fixed boundary conditions. In the present study, it is observed that: • For height 1.33 m, for both the boundary conditions, the minimum and maximum displacements are observed in 5 bay and 2 bay (Ref. Figs. 5 and 6). • For height 1.00 m, for both the boundary conditions, the minimum and maximum displacements are observed in 6 bay and 3 bay (Ref. Figs. 7 and 8). • For height 0.8 m, for both the boundary conditions, the minimum and maximum displacements are observed in 8 bay and 3 bay (Ref. Figs. 9 and 10). Tables 3, 4 and 5 refers to the variation of displacement and reduction in percentage of displacement for different thickness and heights of 1.33, 1.00 and 0.8 m for both hinged and fixed boundary conditions. Displacement reduces, and hence, increase in stiffness is observed for all thickness. Reduction in percentage of displacement is very much helpful in forecasting the economic sections (Table 6).

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Fig. 5 Displacement variation with thickness for H = 1.33 m with hinged boundary condition

Fig. 6 Displacement variation with thickness for H = 1.33 m with fixed boundary condition

Fig. 7 Displacement variation with thickness for H = 1.00 m with hinged boundary condition

Prediction of Effect of Geometrical Parameters in Trough …

Fig. 8 Displacement variation with thickness for H = 1.00 m with fixed boundary condition

Fig. 9 Displacement variation with thickness for H = 0.8 m with hinged boundary condition

Fig. 10 Displacement variation with thickness for H = 0.8 m with fixed boundary condition

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Table 3 Variation of displacement with thickness (75–130 mm) for H = L/15 Number of Bays

Spacing between supports (m)

2

10

Variation of displacement (mm) for hinge condition

% Reduction in Variation of displacement for displacement hinge condition (mm) for fixed condition

% Reduction in displacement for fixed condition

366.17–129.76

64.56

267.61–99.35

62.88

3

6.67

164.39–60.22

63.37

116.38–45.69

60.74

4

5

87.17–36.15

58.53

67.88–29.85

56.03

5

4

58.53–24.87

57.51

46.67–20.92

55.17

Table 4 Variation of displacement with thickness (75–130 mm) for H = L/20 Number of Bays

Spacing between supports (m)

Variation of displacement (mm) for hinge condition

% Reduction in displacement for hinge condition

Variation of displacement (mm) for fixed condition

% Reduction in displacement for fixed condition

3

6.67

171.79–65.49

61.88

127.05–51.39

59.55

4

5

96.26–41.49

56.89

78.06–35.13

54.99

5

4

63.81–29.02

54.52

52.83–25.06

52.56

6

3.33

42.26–20.71

50.99

33.24–17.59

47.08

Table 5 Variation of displacement with thickness (75–130 mm) for H = L/25 Number of Bays

Spacing between supports (m)

Variation of displacement (mm) for hinge condition

% Reduction in displacement for hinge condition

Variation of displacement (mm) for fixed B.C.

% Reduction in displacement for fixed condition

3

6.67

183.39–72.71

60.35

139.65–58.25

58.29

4

5

107.07–48.28

54.91

88.87–41.44

53.37

5

4

70.83–34.97

50.63

59.97–30.63

48.92

6

3.33

46.78–26.13

44.14

38.27–22.79

40.45

7

2.86

37.78–23.36

38.17

31.61–20.69

34.55

8

2.5

36.34–23.48

35.47

32.38–21.48

33.66

2.2 ANN Modeling of Plate The output obtained from SAP 2000 analysis is divided into two sets of data for training and validation in the ratio of 70:30, respectively. Considering height, thickness and number of bays as inputs, the following points were observed in the ANN modeling for hinged and fixed boundary conditions:

Prediction of Effect of Geometrical Parameters in Trough …

231

Table 6 ANN architecture for fixed and hinged boundary conditions Parameters

Fixed BC

Hinged BC

σ x (Compressive)

3-2-1

3-8-1

σ x (Tensile)

3-3-1

3-3-1

σ y (Compressive)

3-3-1

3-8-1

σ y (Tensile)

3-6-1

3-7-1

τ xy

3-2-1

3-5-1



3-2-1

3-2-1

σ x = Normal stress along “X” direction (along span); σ y = Normal stress along “Y ” direction (along width); τ xy = shear stress;  = displacement

Fig. 11 ANN structure for the illustration of Garsons algorithm

• The scatter diagrams of the observed versus predicted output values of all the parameters show that the output can be reasonably well simulated by using the developed ANN model (Ref. Figs. 11, 12 and 13). • Based on the results obtained from network modeling, the ANN architecture of 3-3-1 has shown the optimal results for most of the parameters. • The values of COD and COE are very much closer to 1 for both the boundary conditions. • COD nearly equal to 1 in most of the ANN model implies that the dependent variable can be predicted without much error from the independent variable. • COE nearly equal to 1 in most of the ANN model shows the high prediction capability of ANN model. • The results obtained from Garson’s algorithm calculation indicate that the highest contribution belongs to the number of bays in both fixed and hinged boundary conditions, relative importance ranging from 45% to 91% and 47% to 94%, respectively, in fixed and hinged boundary conditions (Ref. Tables 7, 8, 9, 10, 11, 12 and 13).

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Fig. 12 Network performance of displacement for training data

Fig. 13 Network performance of displacement for validation data

ANN architecture of different models with minimum prediction errors parameters is written in the order of input–hidden nodes–output neurons, i.e., referring to Table 6, 3-number of neuron in the input layer, 3-number of neuron in hidden layers, 1-number of neuron in the output layer.

Prediction of Effect of Geometrical Parameters in Trough …

233

Table 7 COD and COE of training and validation models for different boundary conditions Outputs

Fixed boundary condition

Hinged boundary condition

Training

Validation

Training

Validation

COD = COE

COD

COE

COD = COE

COD

COE

σ x (Compressive)

0.992

0.997

0.992

0.959

0.999

0.998

σ x (Tensile)

0.994

0.996

0.992

0.983

0.995

0.991

σ y (Compressive)

0.999

0.994

0.992

0.989

0.953

0.946

σ y (Tensile)

0.989

0.998

0.993

0.986

0.976

0.965

τ xy

0.992

0.997

0.991

0.995

0.985

0.948



0.991

0.994

0.992

0.993

0.997

0.996

σ x = Normal stress along “X” direction (along span); σ y = Normal stress along “Y ” direction (along width); τ xy = Shear stress;  = displacement COD = Coefficient of determination; COE = Coefficient of efficiency Table 8 Neuron connection weights Hidden neuron

A

Height

B 0.245

0.069

Thickness

0.605

0.978

Number of bays

1.421

5.012

−0.742

−3.197

Displacement

Table 9 Contribution of input neuron to the output via hidden neuron Hidden neuron

A

B

Height

−0.182

−0.221

Thickness

−0.449

−3.127

Number of bays

−1.054

−16.023

Table 10 Relative contribution of input neuron and sum of input neuron contributions Hidden Neuron

A

B

Sum

Height

0.108

0.011

0.119

Thickness

0.266

0.161

0.428

Number of bays

0.626

0.827

1.453

Table 11 Relative importance of input variable Hidden neuron Height

Relative importance (%) 5.96

Thickness

21.39

Number of bays

72.65

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Table 12 Reative importance of input variables for training and validation data with fixed boundary condition Output σ x (c) σ x (t) σ y (c) σ y (t) τ xy Displacement

Relative importance (%) Height

Thickness

Number of bays

Training

23.53

24.30

52.17

Validation

1.40

22.32

76.27

Training

15.99

23.73

60.28

Validation

3.49

31.06

65.45

Training

0.86

18.77

80.37

Validation

1.14

15.19

83.66

Training

32.57

21.78

45.66

Validation

2.63

12.04

85.33

Training

0.86

7.48

91.65

Validation

1.35

13.34

85.31

Training

5.96

21.39

72.65

Validation

1.05

18.57

80.38

Table 13 Relative importance of input variables for training and validation data with hinged boundary condition Output

Relative importance (%) Height

Thickness

Number of Bays

Training

5.63

5.15

89.22

Validation

0.67

5.25

94.08

Training

3.87

5.91

90.22

Validation

1.12

13.91

84.97

σ y (c)

Training

6.96

40.34

52.71

Validation

0.73

26.23

73.04

σ y (t)

Training

4.63

30.89

64.47

Validation

1.12

29.14

69.73

Training

12.80

28.26

58.93

Validation

2.15

50.62

47.23

Training

5.21

22.71

72.09

Validation

1.09

18.86

80.06

σ x (c) σ x (t)

τ xy Displacement

Prediction of Effect of Geometrical Parameters in Trough …

235

3 Conclusions In the present study, the behavior of trough shape folded plate roof is studied in terms of displacement by changing various geometrical parameters. Analytical results are then used to develop artificial neural network model to predict the behavior of folded plate roof and the relative importance of input variable. From the analysis of folded plate roof using the software SAP 2000 (v-20), the following conclusions are drawn: • Displacement decreases as the thickness increases for all the heights and corresponding possible number of bays. • Displacement in the FPR with fixed boundary condition is less when compared to hinged boundary condition due to the restraint capacity at the boundary. • As the number of bay increases the percentage reduction in displacement decreases for both fixed and hinged boundary conditions due to increase in the resisting capacity at the supports. • Stiffness and rigidity of folded plate roof increases with increase in thickness and number of bays which leads to reduction in displacement. • Stiffness and rigidity of folded plate roof reduces with increase in height of folded plate roof. • Economic sections may be selected when reduction in percentage of displacement is found to be the least. The following points were observed in the ANN modeling for hinged and fixed boundary conditions: • By using the developed ANN model, the output can be reasonably well simulated. • A very minute difference is observed between the simulated FEM analysis values and the predicted values, which show good agreement. • Based on the results obtained from network modeling, the ANN architecture of 3-3-1 is suitable for most of the parameters. • Results obtained from Garson’s algorithm indicate that the highest contribution belongs to the number of bays in both fixed and hinged boundary conditions when compared to thickness and height of FPR. • Similar studies have been carried out for predicting the stresses whose sample results are provided in the appendix. Acknowledgements I would like to express my special thanks of gratitude to the second author and institute for supporting this work.

Appendix Sample Design Tables 14, 15 and 16.

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Table 14 Values of stress for height 1.33 m for hinged boundary condition n

t = 130 mm σx

σy

τ xy

C

T

C

T

–

2

202.61

163.62

69.34

54.62

41.21

3

50.92

48.13

54.69

44.63

33.47

4

105.03

74.04

39.65

29.03

27.01

5

88.50

59.38

34.13

23.77

24.25

Table 15 Values of stress for height 1.00 m for hinged boundary condition n

t = 130 mm σx C

σy

τ xy

T

C

T

–

3

49.39

43.88

52.10

41.40

36.03

4

101.75

64.19

37.44

26.47

27.72

5

84.04

49.6

33.44

21.30

24.46

6

26.8

25.27

21.84

30.46

22.17

Table 16 Values of stress for height 0.8 m for hinged boundary condition n

t = 130 mm σx C

σy

τ xy

T

C

C

T

3

48.95

40.87

50.55

39.01

39.29

4

101.96

57.65

40.69

24.68

29.1

5

83.06

43.11

37.18

19.62

25.39

6

24.93

22.69

29.52

19.88

22.9

7

20.87

20.00

27.64

16.81

19.69

8

58.98

23.88

33.41

11.92

21.12

n = number of bay; σ x = longitudinal stress in X direction along span (MPa); σ y = transverse stress in Y direction along width (MPa); τ xy = shear stress (MPa); C = compression; T = tension

References 1. Chauhan S (2016) Folded plate structures. M. Tech thesis, Indian Institute of Technology, Roorkee, India 2. Desai M, Kewate S, Hirkane S (2014) Study of fold and folded plates in structural engineering. Int J Sci Eng Res 5(12) 3. Chacko T, Ramdass S, Ramanujan J (2013) parametric study on transverse and longitudinal moments of trough type folded plate roofs using ANSYS. Am J Eng Res Recent Adv Struct Eng RASE 4:22–28

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4. Elkady H, Hasan A (2010) Effect of geometric configuration of quadratic folded plate roofing system on their static and dynamic behaviour. J Am Sci 6(7):318–326 5. Lakshmy TK, Bhavikatti SS (2005) Optimum design of trough type folded plate roofs. Comput Struct 57(I):U-130 6. IS: 456 (2000) Plain and reinforced concrete code of practice. Bureau of Indian standards, New Delhi 7. IS: 2210 (1988) Criteria for design of reinforced concrete shell structures and folded plates. Bureau of Indian standards, New Delhi 8. IS: 875 (1987) Code of practice for design loads for buildings and structures, part 2 imposed loads. Bureau of Indian standards, New Delhi 9. Kalteh AM (2008) Rainfall-runoff modelling using artificial neural networks (ANNs): modelling and understanding. Caspian J Environ Sci 6(1):53–58 10. Cardozo SD, Gomes HM, Awruch AM (2011) Optimization of laminated composite plates and shells using genetic algorithms, neural networks and finite elements. Latin Am J Solids Struct 8:413–427 11. Krenker A, Bešter J, Kos A (2011) Introduction to the artificial neural networks. Artif Neural Netw Methodol Adv Biomed Appl, 3–5

Analysis of RC Irregular Building According to Different Seismic Design Codes Baburao Anuse and Kiran Shinde

Abstract This paper addresses the analysis of irregular multi-storied RC frame building according to different seismic design codes. A RC multi-story building is subjected to most dangerous earthquake; the main reason for failure of RC buildings is irregularity in its plan dimensions. This paper presents analysis of irregular building using different seismic design codes. Building is compared in terms of structural displacement, drifts and story shear. And also focuses on three seismic design codes India (IS 1893), USA (ASCE 7) and Europe (EC8). Irregular L-shape ten-story buildings are analysed using the equivalent static load method (ESL). Keywords Seismic analysis · Building codes · Irregular plan · Equivalent static analysis · ETABS

1 Introduction A multi-story building having more than 12 floors is known as high-rise building used for residential and commercial building. Many high-rise buildings have been constructed using reinforced concrete structural frames. At the time of earthquake for well performance, the building should have simple configuration, lateral strength, ductility and stiffness; those are the four main attributes are required. Irregular building has a large portion of the modern urban infrastructure. Building structure has mass, stiffness and strength irregularity known as irregular building. Irregular buildings are situated in high seismicity zone; the role of structural engineer is more challengeable. Recently, an extensive change in earthquake design and detailing has been the major cause of many building damages and fails. In an event of earthquake the existing buildings without seismic consideration are the main risk source, and B. Anuse · K. Shinde (B) Department of Civil Engineering, Annasaheb Dange College of Engineering and Technology, Ashta 416301, India e-mail: [email protected] B. Anuse e-mail: [email protected] © Springer Nature Singapore Pte Ltd. 2021 M. C. Narasimhan et al. (eds.), Trends in Civil Engineering and Challenges for Sustainability, Lecture Notes in Civil Engineering 99, https://doi.org/10.1007/978-981-15-6828-2_18

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Fig. 1 Irregular shape building

cause of casualty. Seismic codes are revised on the basis of improvements in soils, ground motions and structures. Plan or elevation irregularity in the structure is the main cause of damage of structure during past earthquakes. This paper primarily refers the plan irregularity. There are different types of plan irregularities such as torsional irregularity, re-entrant corners, diaphragm discontinuity, floor slabs having excessive cutouts or openings, out-of-plane offsets in vertical elements and non-parallel lateral force system (Fig. 1).

2 Literature Reviews Mohammad et al. [1], in this work, they have done the seismic analysis and design of a RC building using US code, Indian code and Bangladesh code. Geometrically, they selected three similar RC buildings from that three different countries. Finally,

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those buildings are compared on the basis of inter-story drifts, roof displacements, beams and columns capacity of load carrying and energy dissipation characteristics. Ahmed et al. [2], in this paper, they have done the Egyptian code, IBC, UBC and European code comparison for the purpose of seismic performance of RC building situated in Egypt. For the analysis, they have choose ten- and twenty-storied RC buildings using response spectrum method (RSM) and equivalent static load method (ESL). Factors like base shear, story drift, shear wall moment and shear wall steel reinforcement are carried out using ETABS software. From the comparison of all codes, they conclude that the IBC is the most reliable code compared to other codes to respective project. Prasanti and Lavanya [3], in this work, they have done the study of seismic analysis and design for different plan configurations in structural behavior of multi-story RC-framed building. The projects aim is seismic analysis and design of G + 20storied building with different plan configurations like rectangular and C-shape using ETABS. Structural displacements, drifts, story shear, overturning moment and stiffness are found out from the linear static and response spectrum analysis method. They conclude that the behavior of a building rectangular shape is always better than the C-shape. Albert and Elavenil [4] studied the seismic analysis of high-rise building with plan irregularity. On ETABS software, they generated analytical model for regular and irregular G + 12-storied RC buildings. After comparison, the irregular building has more displacements, story drifts and story shear than regular building. And also, both the structures are having overturning moment which is approximately equal to zero. Panduranga Rao and Mahesh [5], in this paper, they compare design and analysis of regular and irregular buildings with respect to different soils and different seismic zones using StaadPro and ETABS. They have done study of G + 11-storied building under the earthquake load and wind load. For both rectangular and T-shaped buildings, result performance level has been overreached, and in some cases, the building reaches the collapse prevention level. These happen mainly because of neglect foundation flexibility. On the basis of that, they suggested that the code provisions still need improvement, especially on the flexibility of number of elements and their locations. Jaime et al. [6] analyzed the RC irregular building according to different seismic codes. This paper compares three seismic design codes, Philippine code (NSCP2010), European code (EC8) and International Building Code (IBC). Equivalent lateral force analysis and response spectrum method, both methods, are used to analyze the structure by using SAP2000 software. They concluded that in the load combination cases, EC8 considered the effects of earthquake actions in both directions which are not considered in the NSCP2010 and IBC standards. Also, the larger reinforcement is required for EC8 compared to other two codes. Bahador et al. [7], they have done the static analysis and dynamic analysis of irregular multi-story building. In this project, 20-storied building was modeled and analyzed using SAP and ETABS in seismic zone (v). Also, consider the height variation effect on the structural response of shear wall building. They conclude

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that the approximately uneconomical results of equivalent static analysis compared to dynamic analysis the displacement values are higher. Also, they suggested that for high-rise buildings static analysis is insufficient, and it is replaced to dynamic analysis. Athanassiadou [8], this paper addresses the two ten-story two-dimensional with two and four large setbacks; those are designed in Eurocode 8 (EC8) for medium and high ductility classes. These two frames are analyzed by using time history analysis and static pushover analysis. Finally, they conclude that the building cost is negligible with respect to ductility class effect, while equally satisfaction of irregular frames for seismic performance. Also, the medium ductility class frames are stronger and less ductile than respective high ductility classes frames.

3 Analysis of Data In proposed project work, there is analysis of G + 9-storied L-shape (irregular) building using various seismic design codes. Modeling of the irregular shaped building is done using ETABS Software. The chosen standards are Indian, American and European codes for the purpose of seismic analysis. A comparative analysis is performed in terms of displacement, base shear and drifts for different codes. Also, in analysis part, there is consideration of different loading combinations, such as combination of dead load, live load, earthquake load.

4 Objectives 1. The chosen standards are Indian Standard Code IS: 1893, Eurocode EC8 and American Code ASCE 7. 2. A comparative analysis is performed in terms of story displacement, base shear and story drifts for different codes. 3. Also, analysis of building is carried out under different loading combinations, such as combination of dead load, live load, earthquake load. 4. Study the behavior of multi-story L-shape irregular building on ETABS Software.

5 Methodology (a) Modeling of the irregular L-shape building in ETABS software. (b) Three models are made as per the codes, i.e., Indian code, Eurocode, American code specification. (c) Applied calculated lateral seismic forces and load combinations as per IS 1893, Eurocode 8 and ASCE 7 [9–14].

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6 Building Configurations 1. Building geometry Plan dimensions Floor to floor height Ground floor height Number of stories Total height of building Support condition

17.5 m × 18.5 m 3.0 m 3.0 m G+9 30 m Fixed

2. Material property Grade of concrete Grade of steel Density of reinforced concrete Density of brick masonry

M20 Fe500 25 kN/m3 20 kN/m3

3. Member property Beam size Column size Thickness of brick wall Thickness of RCC slab

400 × 650 mm 400 × 900 mm 230 mm 125 mm

4. Seismic parameters details Seismic zone Zone factor Soil type Importance factor Response reduction factor

Zone II 0.16 Medium 1.2 5

Also, the same parameters are converted according to American code and European coden (Figs. 2 and 3).

7 Analysis Result The analysis results are in terms of story displacement, story shear and story drift (Figs. 4, 5, 6 and 7). 1. According to IS-1893 (a) Story displacement (b) Story drift (c) Story shear

244 Fig. 2 Typical plan of building model

Fig. 3 The 3D Elevation of building

B. Anuse and K. Shinde

Analysis of RC Irregular Building According to Different … Fig. 4 Maximum story displacement

Fig. 5 Maximum story drift

Fig. 6 Maximum story displacement

Fig. 7 Maximum story drift

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Fig. 8 Maximum story displacement

Fig. 9 Maximum story drift

Maximum story shear for IS-1893 is 335,221 KN. 2. According to ASCE7-10 (a) Story displacement (b) Story drift (c) Story shear Maximum story shear for ASCE-7 is 541.70 kip (2409.64 KN) (Figs. 8, 9, 10, 11 and 12). 3. According to EC8 (a) Story displacement (b) Story drift (c) Story shear Maximum story shear for Eurocode (EC 8) is1560.35 KN. 4. Comparison of three codes with respect to story displacement, story drift and story shear. (a) Story displacement (b) Story drift (c) Story shear

Analysis of RC Irregular Building According to Different … Fig. 10 Comparison of story displacement

Fig. 11 Comparison of story drift

Fig. 12 Comparison of story shear

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8 Conclusion From the above analysis results, the followings are concluded. Maximum story displacement according to Euro code is much smaller than Indian code and American code. Also, the maximum story drift according to Eurocode is less than other two codes. Story displacements of all codes are in permissible limit according to their codes considerations. Story shear is maximum in Indian compared to other two codes.

References 1. Mohammad MR, Sagar MJ, Bahram MS (2018) Seismic performance of reinforce concrete buildings designed according to codes in Bangladesh, Indian and U.S. Eng Struct 160:111–120 (Elsevior, USA) 2. Ahmed M, Hoda S, Ayman AS (2018) Comparison of Egyption code 2012 with Eurocode 8-2013, IBC 2015 and UBC 1997 for seismic analysis of residential shear-walls RC buildings in Egypt. Ain Shams Eng J 9:3425–3436 (ScienceDirect, Egypt) 3. Prashanti T, Lavanya PM (2017) To study of seismic analysis and design for different plan configuration in structural behaviour of multi-story RC framed building. IJIRT 3:49–53 (India) 4. Albert P, Elavenil S (2017) Seismic analysis of high rise buildings with plan irregularity. Int J Civ Eng Technol (IJCIET) 8:1365–1375 (India) 5. Mahesh T, Pandurangarao SB (2014) Comparison of analysis and design of regular and irregular configuration of multi-story building in various seismic zones and various types of soils using ETABS and STAAD. IOSR J Mech Civ Eng (IOSR-JMCE) 11:45–52 (India) 6. Jaime L, Hugo R, Humberto V, Antonio A, Anibal C (2013) Comparative analysis of RC irregular buildings designed according to different seismic codes. Open Construct Build Technol J, 221–229 (Portugal) 7. Bahador B, Ehsan SF, Mohammadreza Y (2012) Comparative study of the static and dynamic analysis of of multi-story irregular building. Int J Civ Environ Eng 6(11):1045–1049 (India) 8. Athanassiadou CJ (2008) Seismic performance of RC plane frames irregular in elevation. Eng Struct 30:1250–1261 (ScienceDirect, Greece) 9. IS 456:2000 Plain and reinforced concrete—code of practice (Fourth Revision). Bureau of Indian Standard, New Delhi 10. IS 1893 (Part 1) (2002) Criteria for earthquake resistant design of structures Part 1 general provisions and buildings (Fifth Revision). Bureau of Indian Standard, New Delhi 11. ASCE 7 Minimum Design Loads for Building and other Structures (ASCE 7-02) American Society of Civil Engineers, New York 12. Building Code Requirements for Structural Concrete (ACI 318-14) 13. EN 1992 (2004): Eurocode 2: Design of concrete structures - Part 1-1: General rules and rules for buildings 14. EN 1998-1 (2004): Eurocode 8: Design of structures for earthquake resistance—Part 1: General rules, seismic actions and rules for buildings

Study of Behaviour of High Rise Buildings with Diagrid Systems Mangesh Vhanmane and Maheshkumar Bhanuse

Abstract High-rise structures are growing speedily around the world. The unique geometric arrangement of the system provides the efficiency of structure and beauty capabilities; the new structural system with diagrid has been used extensively for the recent high buildings. The diagrid is an arrangement of triangulated beams; it has a straight or curved and horizontal ring system which makes the combined structural system for skyscrapers. Diagrid structure uses fewer materials than traditional structural systems with orthogonal members. The efficiency of diagrid system reduces number of inner columns so that the design of the plan gets more flexibility. This research study aims to explore the applicability of diagrid systems in high-rise buildings, over conventional construction systems. A square plan 32 m × 32 m dimensions is taken to study of behaviour of high rise building with a diagrid system. All structural members like beams, columns, etc., are analysed considering all load combinations as per IS 800:2007. Similarly, analysis of G + 40-, G + 60- and G + 80-storied structures with diagrid system is taken for comparison of the results for parameters like storey shear, storey drift and storey displacement which are also represented in paper. For modelling and analysis purpose, ETABs software is used. Keywords High-rise buildings · Diagrid systems · Gravity and lateral load resistance · ETABs 2017

M. Vhanmane (B) · M. Bhanuse Department of Civil Engineering, Annasaheb Dange College of Engineering and Technology, Ashta 416301, India e-mail: [email protected] M. Bhanuse e-mail: [email protected] © Springer Nature Singapore Pte Ltd. 2021 M. C. Narasimhan et al. (eds.), Trends in Civil Engineering and Challenges for Sustainability, Lecture Notes in Civil Engineering 99, https://doi.org/10.1007/978-981-15-6828-2_19

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1 Introduction The population, scarcity and high cost of land had huge impact on the rapidly growing industry. This has led to the construction of buildings in upward direction. Due to modern technology in construction, development, structural systems, materials, analysis and design software, high-rise buildings have been developed. Due to increase in height of building, lateral resistance systems are much important than structural resistance due to vertical loads. The rigid frame system, shear wall system, wallframe system, braced frame system, outrigger system and tubular systems are most commonly used systems for lateral load resistance. Diagrid structural system can be combined to create a triangle shape that is made of very nice artwork or can be seen as a grid shape. The “diagrid” is made from combination of two words, i.e. “diagonal” and “grid”. Less structural steel is required for diagrids as compared to traditional steel frames. The diagrid looks good also easy to know. Shape of structure and the efficiency of the diagrid reduce the number of necessary structural elements on periphery building, avoiding obstructions in exterior view. Diagrid structural system tends to exclude internal and corner columns, resulting in great flexibility in floor plan. Generally, the work of high-rise buildings has been done as a commercial office building. Another application like as residential and hotel tower development have increased speedily. Development of high-rise buildings includes various complex elements like economic, aesthetic, technology, municipal rules and politics. In this, economic is main administrative component. Lateral stiffness is normally controlled using structural design for very high building structure.

2 Literature Review Boake [1] described the expansions in the current history of diagrid structures, which contains the detailing, erection, design and fabrication issues. The decision to fast or cover the structure impacts the design of the building is identical exclusive ways given the angular nature of that new geometry. It was the resolution of work to provide a relative understanding of the design requirements and describing of such structures via inspection of significant present examples. Mele et al. [2] focused on the structural performance of some current diagrid tall structures which were classified by a different number of stories and different geometries. Application of the diagrid structural arrangement is adopted in tall building due to its structural efficiency. Milana et al. [3] studied the structural performance by the use of nonlinear analysis in finite element method (FEM). Differentiation in between a traditional framework system and various diagrid arrangements with three different inclination angles of diagrid is done, and the building was of 40 storeys with a total height of 160 m. Korsavi et al. [4] included the different 30 case studies that are carried out for finding the evolutionary process of diagrid structures. The heights, areas or locations,

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number of stories, diagrid angles and modules in diagrids are studied. Rathod et al. [5] described the significance of different forms of diagrid structures like freeform, tilted, twisted, tapered, etc. Diagrid steel assemblies were related to the conventional assemblies. The optimal diagrid angle, diagrid plans and various forms of diagrid structures were investigated. Thomas et al. [6] described the performance evolution of 36-storey building with storey height 3.6 m. Different diagrid modules were used such as 2, 4, 6, 8, 12 storey modules. Representative plan of square, rectangular and circular buildings are considered. Yadav et al. [7] studied regular steel building G + 15 storey with a plan of size 18 m × 18 m and storey height 3.0 m. Storey module 4 and 63.43° diagrid angle were used. Conventional and diagrid systems were compared. STAAD Pro software was used. Shah et al. [8] studied 7 steel building structures of the defined plan area, and different loads on various heights are analysed and designed for optimum members for the conventional and diagrid construction in ETABS. The building plan of size 18 m × 18 m and storey height 3.0 m was located at Bhuj. Bhuiyan et al. [9] studied three buildings with 38, 64, 82 storeys with height 133 m, 224 m and 287 m and with plan size 33 m × 33 m, 52 m × 35.5 m and 48 m × 48 m, respectively. Determine the optimal member sizes and configuration for diagrid structures. Nimisha et al. [10] studied the structural efficiency of tubular, and diagrid building structures of 24, 30, 36, 42, 48, 54, 60, 66 storeys are considered plan area 32 m X 32 m with storey height 3.8 m, 6 storey modules and 70.6° angle. ETABs software was used. Mascarenhas et al. [11] work carried out for behaviour of diagrid structures with various aspect ratios, such as 1:1, 1:2, 1:3 and 1:4. G + 60-storey diagrid building with diagrid angles of 33.69°, 53.13°, 63.43° and 69.44° was considered. ETABs software was used. Kinjawadekar et al. [12] prepared the two sets of 18 and 36-storey structure with storey height 3 m. 2, 3 and 4 storey module with the diagonal angle of 45°, 64° and 72° was considered. SAP 2016 software is used for design. Akshat et al. [13] worked on the comparison of regular building structures with the new alternative of different geometrical configurations obtained by a change in the angle of diagrid and also change in a number of diagonal members along with the height of the building structure.

3 Objectives 1. Modelling of high-rise buildings structures with diagrid arrangements of different angles. 2. To study the behaviour of high-rise buildings structures with diagrid arrangements under gravitational and lateral forces. 3. To study the behaviour of high-rise buildings structures with diagrid arrangements for different parameters such as storey displacement, storey drift, base shear.

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4 Problem Formulation The present study involves the study of high-rise buildings with diagrid systems of different angles to find the optimum diagrid angle for a particular height.

5 Methodology In this work, analysis of G + 40-, G + 60- and G + 80-storied diagrid structure is presented. Lateral forces due to earthquake and wind effect are considered as per Bureau Indian Standard. IS 1893:2016 and IS 800:2015 were used for the analysis of the structure. Modelling and analysis of diagrid buildings are carried out using Etabs software. Response spectrum analysis is done for earthquake loads. For linear static analysis and dynamic analysis, the beams and columns are modelled as flexural elements and diagonals as truss elements. Support conditions of diagonals are assumed as hinged support. Temperature variation is not considered. To achieve the optimum angle for diagrid structural system, G + 40-, G + 60- and G + 80storied steel structures are considered. To find out optimum angle, four different cases having an angle of diagonal 56.18°, 66.2°, 71.33° and 75.4° with 4, 6, 8 and 10 storey modules, respectively, are considered for each diagrid structure. The analysis is done by considering the optimum angle of diagrid system on the periphery. A. Building configuration See Table 1 and Figs. 1, 2 and 3. B. Diagrid angles See Table 2. C. Section properties details Table 1 Details of building configuration

Structure type

Steel structure

Number of stories

G + 40, G + 60, G + 80

Size of plan

32 m x 32 m

Number of bays along X and Y

8

Spacing between bays

4m

Spacing between diagrid along perimeter

8m

Height of each storey

3m

Number storeys per module

4, 6, 8, 10

Grade of structural steel (Fy)

Fe 345

Grade of concrete (Fck)

M30

Study of Behaviour of High Rise Buildings with Diagrid Systems

Fig. 1 Typical building plan of model

(a) Without diagrid module See Table 3. (b) 4-Storey Module See Table 4. (c) 6-Storey Module See Table 5. (d) 8-Storey Module See Table 6. (e) 10-Storey Module See Table 7. (f) Slab details Type

RCC Slab

Thickness

150 mm

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Fig. 2 Elevations of four- and six-storey module

(g) Loads Dead Load

6.5 KN/m2

Live Load

25 KN/m2

(h) Seismic parameters details: (As per IS 1893-2016)

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Fig. 3 Elevations of eight- and ten-storey module Table 2 Diagrid angles for each storey module

Number storeys per module

Angle

0

0°

4

56.18°

6

66.2°

8

71.33°

10

75.4°

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Table 3 Section properties details for without diagrid module Building model Storeys Beam (Indian Column (Steel tubes) Diagrid (Steel pipes) standard wide flange beam) G + 40 storey

G + 60 storey

G + 80 storey

1–20

ISWB 400

21–32

ISWB 450

33–40

ISWB 500

1–24

ISWB 400

25–44

ISWB 450

45–60

ISWB 500

1–40

ISWB 400

41–66

ISWB 450

67–80

ISWB 500

450 × 450 × 15 mm

–

700 × 700 × 15 mm

–

950 × 950 × 15 mm

–

Table 4 Section properties details for 4-storey module Building model Storeys Beam (Indian Column (Steel tubes) Diagrid (Steel pipes) standard wide flange beam) G + 40 storey

G + 60 storey

G + 80 storey

1–20

ISWB 400

21–32

ISWB 450

33–40

ISWB 500

1–24

ISWB 400

25–44

ISWB 450

45–60

ISWB 500

1–40

ISWB 400

41–66

ISWB 450

67–80

ISWB 500

450 × 450 × 15 mm

450 × 25 mm

700 × 700 × 15 mm

675 × 25 mm

950 × 950 × 15 mm

875 × 50 mm

Table 5 Section properties details for 6-storey module Building model Storeys Beam (Indian Column (Steel tubes) Diagrid (Steel pipes) standard wide flange beam) G + 40 Storey

G + 60 storey

G + 80 storey

1–20

ISWB 400

21–32

ISWB 450

33–40

ISWB 500

1–24

ISWB 400

25–44

ISWB 450

45–60

ISWB 500

1–40

ISWB 400

41–66

ISWB 450

67–80

ISWB 500

450 × 450 × 15 mm

450 × 25 mm

700 × 700 × 15 mm

675 × 25 mm

950 × 950 × 15 mm

875 × 50 mm

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Table 6 Section properties details for 8-storey module Building model Storeys Beam (Indian Column (Steel tubes) Diagrid (Steel pipes) standard wide flange beam) G + 40 storey

G + 60 storey

G + 80 storey

1–20

ISWB 400

21–32

ISWB 450

33–40

ISWB 500

1–24

ISWB 400

25–44

ISWB 450

45–60

ISWB 500

1–40

ISWB 400

41–66

ISWB 450

67–80

ISWB 500

450 × 450 × 15 mm

450 × 25 mm

700 × 700 × 15 mm

675 × 25 mm

950 × 950 × 15 mm

875 × 50 mm

Table 7 Section properties details for 10-storey module Building model Storeys Beam (Indian Column (Steel tubes) Diagrid (Steel pipes) standard wide flange beam) G + 40 storey

G + 60 storey

G + 80 storey

1–20

ISWB 400

21–32

ISWB 450

33–40

ISWB 500

1–24

ISWB 400

25–44

ISWB 450

45–60

ISWB 500

1–40

ISWB 400

41–66

ISWB 450

67–80

ISWB 500

450 × 450 × 15 mm

450 × 25 mm

700 × 700 × 15 mm

675 × 25 mm

950 × 950 × 15 mm

875 × 50 mm

Seismic zone

Zone III

Zone factor

0.16

Soil type

Medium

Importance factor

1.2

Response reduction factor

5

(i) Wind parameters details: (As per IS 875-2015) Place

Pune (continued)

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(continued) Wind speed

39 m/s

Terrain category

2

Structure class

B

Risk coefficient

1

Topography factor

1

6 Analysis Result The results of the analysis in terms of storey shear, storey displacement and storey drift are presented below. Following graphs shows the maximum values of storey shear, storey displacement and storey drift for G + 40-, G + 60-, G + 80-storey high-rise buildings (Figs. 4, 5, 6, 7, 8, 9, 10, 11 and 12).

7 Conclusion • The analysis result shows that for G + 40- and G + 60-storey building with the storey module 6 gives the least values of storey displacement and storey drifts. • Also, for G + 80-storey building with the storey module 8 gives the least values of storey displacement and storey drifts.

Fig. 4 Maximum storey shear for G + 40-storey building

Study of Behaviour of High Rise Buildings with Diagrid Systems

Fig. 5 Maximum storey shear for G + 60-storey building

Fig. 6 Maximum storey shear for G + 80-storey building

Fig. 7 Maximum storey displacement for G + 40-storey building

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Fig. 8 Maximum storey displacement for G + 60-storey building

Fig. 9 Maximum storey displacement for G + 80-storey building

Fig. 10 Maximum storey drift for G + 40-storey building

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Fig. 11 Maximum storey drift for G + 60-storey building

Fig. 12 Maximum storey drift for G + 80-storey building

• This means the module 6 with diagrid angle 66.2° is suitable for G + 40- and G + 60-storey building, and module 8 with diagrid angle 71.33° is suitable for G + 80-storey building. • From this work, it is concluded that the diagrid angle ranging between 65° and 72° is best suitable for height ranges between 120 and 240 m.

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References 1. Boake TM (2013) Diagrids, the new stability system: combining architecture with engineering. School of Architecture, University of Waterloo, Canada 2. Mele E, Toreno M, Brandonisio G, De Luca A (2014) Diagrid structures for tall Buildings: case studies and design considerations. The Structural Design of Tall and Special Buildings, Wiley Online Library, pp 124–145 3. Milana G, Olmati P, Gkoumas K, Bontempi F (2014) Sustainability concepts in the design of high-rise buildings: the case of diagrid systems. In: 3rd international workshop on design in civil and environmental engineering, pp 21–23 4. Korsavi S, Maqhareh MR (2014) The evolutionary process of diagrid structure towards architectural, Struct sustainability. J Archi Eng Technol 3(2) 5. Rathod NG, Saha P (2015) Diagrid- An innovative technique for high rise structures. J Civ Eng Environ Technol 2(5):394–399 6. Thomas FM, Issac BM, George J (2015) Performance evaluation of tall buildings with steel diagrid system. In: 2nd international conference on science, technology and management 7. Yadav S, Garg V (2015) Advantages of steel diagrid building over Conventional building. Int J Civ Struct Eng Res 3(1):394–406 8. Shah M, Mevada SV, Patel VB (2016) Comparative study of diagrid structures with conventional frame structures. Int J Eng Res Appl 6(5)(part-2):22–29 9. Bhuiyan MT, Leon R (2016) Preliminary design of diagrid tall building. In: IAJC-ISAM international conference 10. Nimisha P, Krishnan N (2016) Structural comparison of diagrid building with tubular building. Int J Eng Res Technol (IJERT) 5(4) 11. Mascarenhas DP, Aithal DS (2017) Study on diagrid structures with various aspect ratio under the action of wind. Int J Adv Res Ideas Innov Technol 3(4) 12. Kinjawadekar TA, Kinjawadekar AC (2018) Comparative study of seismic characteristics of diagrid structural systems in high rise construction. Int J Civ Eng Technol 9(6) 13. Akshat, Singh G (2018) A review on the structural performance of diagrid structural systems for high rise buildings. Int J Innov Res Sci Eng Technol 7(2) 14. IS 1893 (Part 1) (2002) Criteria for earthquake resistant design of structures Part 1 general provisions and buildings (fifth revision). Bureau of Indian Standard, New Delhi 15. IS 456 (2000) Plain and reinforced concrete—code of practice (fourth revision). Bureau of Indian Standard, New Delhi 16. IS 800 (2007) General construction in steel—code of practice (third revision). Bureau of Indian Standard, New Delhi 17. IS 875 (Part 1) (1987) Code of practice for design loads (other than earthquake) for buildings and structures part 1 dead loads – unit weights of building materials and stored materials (second revision). Bureau of Indian Standard, New Delhi 18. IS 875 (Part 2) (1987) Code of practice for design loads (other than earthquake) for buildings and structures part 2 imposed loads (second revision). Bureau of Indian Standard, New Delhi 19. IS 875 (Part 3) (1987) Code of practice for design loads (other than earthquake) for buildings and structures part 3 wind loads (second revision). Bureau of Indian Standard, New Delhi

Constructive Scope on Implementation of Copper Slag as Replacement for Natural Fine Aggregate—An Overview Y. T. Thilak Kumar, D. Arpitha, V. J. Sudarshan, C. Rajasekaran, and Nagesh Puttaswamy Abstract This paper communicates organized work on copper slag drawn from scientific literature which comprises evaluation of physical and chemical characteristics, mechanical and durability properties in the marine environment. Analysis of test data derived from previously available sources reveals that copper slag having similar basic characteristics is an acceptable alternative material to river sand to produce concrete of all grades. The lesser water absorption property of copper slag is very significant peculiarity which attributes to develop high strength in concrete. The behaviour of concrete produced using copper slag to the concrete made corresponding to sand component shows identical behaviour in the fresh and hardened states. As an aggregate, copper slag has an ability to be replaced with fine aggregate, thereby the advance progress in the concrete technology will revolutionize the mixture of different conventional ingredients to uplift the expected properties of concrete to renew its definition. Hence, alternative materials to be used as fine aggregate will reduce the burden on the environment which is being extensively investigated all over the world looking to the significant requirements, quality and properties which have been a global consensus on the materials.

Y. T. Thilak Kumar (B) · D. Arpitha · V. J. Sudarshan · C. Rajasekaran Department of Civil Engineering, National Institute of Technology Karnataka, Surathkal, Karnataka, India e-mail: [email protected] D. Arpitha e-mail: [email protected] V. J. Sudarshan e-mail: [email protected] C. Rajasekaran e-mail: [email protected] N. Puttaswamy Ultratech Cement Ltd., Bengaluru, Karnataka, India e-mail: [email protected] © Springer Nature Singapore Pte Ltd. 2021 M. C. Narasimhan et al. (eds.), Trends in Civil Engineering and Challenges for Sustainability, Lecture Notes in Civil Engineering 99, https://doi.org/10.1007/978-981-15-6828-2_20

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Keywords Concrete · Copper slag · Replacement with sand · Review · Waste · Mechanical properties

1 Introduction Due to the rapid development in construction industries, there is a huge demand for concrete and the world has recorded a rapid increase in the utilization of concrete consistently. Due to the increase in the requirement of concrete, there is a huge depletion of natural resources. This forced civil engineers to think about choosing an alternative material to replace natural resources as an effective, economical and environmentally friendly to produce concrete for sustainable development. However, selecting appropriate materials, contemporary techniques/methods for eco-efficient activities, recycling/reuse of waste materials and so on are the main various innovative strategies which led the stepping stone for the development of the sustainable development in the construction sector. Also, according to studies, reuse of waste materials can significantly improve the green construction. Copper slag is easily available industrial bi-product obtained during matte smelting process in the production of copper. Approximately 3 tons of copper slag is generated for every ton of copper production [1] annually around 24.5 million tons of copper slag bi-product generated worldwide [2], among which 6–6.5 million ton is generated in India [3] and 2 million tons generated in Japan (According to Ayano and Sakata [4]). In India, we can get copper slag in huge amount at Tuticorin in Tamil Nadu. Concrete consumes around 70% of aggregates, which consist of 40% of sand. The scarcity of sand has increased the cost of construction which is uneconomical. This review works effectively that focuses on the importance of copper slag as an eco-friendly material for sand that takes a leaping step in creating a new trend in concrete technology.

2 Material Properties 2.1 Physical Properties Physical properties of copper slag reviewed from past researches by different authors from different locations are mentioned in Table 1. According to Geetha et al. [3], copper slag exhibits almost similar properties of that river sand; hence, copper slag can be used as replacement aggregate in concrete. Copper slag observes lesser moisture due to which water–cement ratio can be reduced depending upon the slump required, but increase in copper slag workability increases [5] reduction in w/c ratio effects in the development of higher strength. The specific gravity varies from 3.36 to 3.91 according to the iron content present; hence, copper slag is denser compared to sand. The hardness of copper slag is 6–7 mohs, and hence, it can be used for floors

Constructive Scope on Implementation of Copper Slag …

265

Table 1 Basic properties of sand and copper slag Properties

Sand

CS

Particle shape

Irregular

Irregular

Appearance

Brownish yellow

Black and glassy

Specific gravity

2.57–2.77

3.36–3.91

Bulk density (g/cc)

1.71

2.08

Fineness modulus

2.58–4.7

2.61–4.33

Water absorption (%)

1.12–1.5

0.15–0.64

Moisture content (%)

0.50

0.10

Al-Jabri et al. [7], Brindha and Nagan [9], Mithun et al. [10], Ambily et al. [11], Geetha and Madhavan [3]

and pavements [6]. Using copper slag in place of fine aggregate results in lesser shrinkage of concrete which improves both mechanical and long-term properties of mortar and concrete. Particle size distribution of different samples of CS is produced by different location and studied by a different author [1, 7, 8]. According to the graph, maximum samples fall under zone 2 (Fig. 1).

Fig. 1 Grain size distribution of copper slag

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Table 2 Chemical compositions of copper slag Constituents

% Range

CaO

0.15–6.06

Al2 O3

0.22–6.06

Fe2 O3

49.3–68.3

SiO2

25.84–35

MgO

0.2–1.56

Na2 O

0.14–0.95

K2 O

0.03–1.02

SO3

0.11–1.89

TiO2

0–0.41

LoI

6.59

Mn2 O3

0.01–0.22

CuO

0.42–1.2

Al Jabri et al. [7], Brindha and Nagan [9], Mithun et al. [10], Ambily et al. [11], Abhishek et al. [12], Qun lye et al., Sharma and Khan [8], Geetha and Madhavan [3]

2.2 Chemical Properties From Table 2, it can be inferred that iron and silica contents in the copper slag are more. It is evident that it can be used as a binder in concrete, and finer copper slag can be used to replace with cement or else can be used to prepare cement.

2.3 Mechanical Properties 2.3.1

Compressive and Tensile Strength

The compressive and tensile strengths presented from the published papers [1, 5, 7, 8–9, 15] explain the strengths of different grade of concrete with different mixes, different binder replacement and with different percentage of copper slag replacement. Different authors observed different behaviours in strength parameter depending upon the type and location of the copper slag generated. But according to Al Jabri et al. [7], Brindha and Nagan [9], Rahul et al. and [10], the strength of concrete gradually increases with respect to the percentage of replacement of copper slag up to 30–40% (25–32% of strength increased compared to control concrete cubes), and after that, there is a decrease in strength development. The split tensile strengths were conducted, and their behaviour with CS replacement is very similar to compressive strength and within the permissible limits.

Constructive Scope on Implementation of Copper Slag …

2.3.2

267

Flexural Strength

To find out flexural strength, authors cast prisms of size 100 × 100 × 500 mm [3, 7, 13, 10, 14] and 70 × 70 × 350 mm [11] and tested under third-point loading condition. According to Wei Wu and KS Al Jabri for the high-strength concrete, the flexural strength decreases with increase in the percentage of CS beyond 30% replacement due to the porosity induced by the trapped excess water inside the concrete specimen. Geetha and Madhavan [3] explained that the incorporation of CS will increase the flexural strength (author studied only up to 20% replacement) for the marine environment. Author Chang Woo Hong states that up to 60% replacement of CS flexural strength increases. Mithun et al. [10] state that CS used with alkali-activated slag concrete did not show any differential behaviour with respect to flexural strength when compared to conventional concrete. But by reducing water-to-binder ratio, flexural strength can be expected more up to certain CS replacement (Table 3).

2.4 Durability 2.4.1

Chloride Attack

Rapid chloride penetration test has resulted that incorporation of CS as a partial replacement of fine aggregate in concrete is suitable for the marine environment and the ingress of chloride ions falls within the acceptable limits when compared to conventional concrete (Geetha et al.). The 28 day cured 100 mm dia, and 50mm-thick concrete specimens showed that chloride penetration decreases with the increase in CS percentage replacement. Mithun et al. confirm that chloride diffusion is much lesser in the case of alkali-activated concrete.

2.4.2

Sulphate and Magnesium Attack

Concrete samples were immersed under 10% of sodium and 10% of magnesium sulphate for the 1-year duration. The substantial increase in the compression strength of alkali-activated concrete cubes submerged under sodium sulphate GGBS and CSbased concrete cubes was recorded when compared to OPC-based control concrete cubes. On the other hand, GGBS and CS-based concrete cubes showed higher strength loss when compared to OPC-based concrete cubes which were immersed in magnesium sulphate (Mithun et al.).

3

26

25.5

24.5

23

60

80

100

29

100

40

27.8

80

23

37.7

60

23.5

38.1

50

20

38.7

0

40.2

40

55

20

42.5

100

53.5

38.8

39.5

75

51

52.5

10

41

50

36.2

39.5

25

42

50.5

0

40.5

0

2

24

0

1

90 Day

59

34

36

37

38.5

34

32

35.1

34.8

46

47

47.1

47

46

45

64

62.5

62

65

62.5

35.5

36.5

39

41

43

38.5

3.45

3.5

3.9

3.7

3.45

3.3

3.4

3.6

3.6

4.1

3.8

3.7

3.5

3

4.83

4.85

4.63

4.81

4.78

4.22

28 Day

56 Day

ft (MPa)

28 Day

3 Day

7 Day

Compressive strength (MPa)

% CS replacement

S. No.

Table 3 Statistical compressive strength and tensile strength data

Sharma and Khan [8]

Al-Jabri et al. [7]

Mithun and Narasimhan 1

Author

(continued)

SCC OPC 1:1.85:1.27 W/C 0.45 SP 3.85–6.6

OPC concrete M45 w/c 0.5 1:1.73:2.47

First sample is 100% OPC all other samples are 100% GGBS

Remarks

268 Y. T. Thilak Kumar et al.

7

6

5

25.6

39.7

0

60

82

46.67

63

100

84

83

40

64

80 35.11

69

60

97

43.4

78

50

96

96

100

94

65

69.5

87.7

95.1

20

76

40

98.5 96.5

0

75

20

47.9

100

80

51.7

80

10

74.3

60

77

75.7

40

0

82

79.1

20

4

90 Day

65.5

71.2

98.4

99.7

102.6

104.1

3.924

4.576

3.961

3.354

4.4

4.7

4.8

61

6.1

6.2

5.2

5.4

4.2

4.1

5.3

5.4

5.4

5.6

28 Day

56 Day

ft (MPa)

28 Day

3 Day

7 Day

Compressive strength (MPa)

0

% CS replacement

S. No.

Table 3 (continued)

Madhavi et al. [15]

Brindha and Nagan [9]

Al-Jabri et al. [5]

Wu et al. [13]

Author

(continued)

1:1.61:2.74 M30 w/c 0.45

1:1.66:3.76 w/c 0.45 M20

High Strength 1:1.6:2.68 M85 w/c 0.35 SP 0.79

High strength 1:1.3:1.3 w/c 0.3 SP 0.27

Remarks

Constructive Scope on Implementation of Copper Slag … 269

27.6

33.3

25.8

40

60

90 Day

28 Day

56 Day

ft (MPa)

28 Day

3 Day

7 Day

Compressive strength (MPa)

20

% CS replacement

ft tensile strength

S. No.

Table 3 (continued) Author

Remarks

270 Y. T. Thilak Kumar et al.

Constructive Scope on Implementation of Copper Slag …

271

3 Conclusions 1. Basic properties like particle size, grading, lower water absorption and low water demand make the material most viable alternative to fine aggregates. 2. Due to the decrease in the water absorption, the concrete mix does not demand high water–binder ratio. This results in better performance of concrete in both fresh and hardened states. 3. A clear indication has been drawn from previous research works that incorporation of copper slag as a partial replacement for fine aggregates has improved the durability properties of concrete in concerned to ingression of chloride and sulphate ions. 4. Also, the problem of dumping these waste materials has been overcome, thereby reducing the scarcity of river sand which in turn has made the concrete ecofriendly. 5. The physical and chemical compositions of copper slag have shown remarkable results in achieving higher-strength and higher-performance concrete. 6. Compressive strength increases up to 30–40% of partial replacement; thereafter, its strength decreases. Hence, by studying the strength behaviour, IS383-2016 recommends the replacement up to 50% Acknowledgements The author would like to thank all the research articles and the respective authors for providing valuable information and acknowledge the support of National Institute of Technology Surathkal, Karnataka, India. Also, the author would like to extend sincere thanks to Sterlite Copper Plant, Tamil Nadu, India, for supplying the copper slag.

References 1. Mithun BM, Narasimhan MC (2016) Performance of alkali activated slag concrete mixes incorporating copper slag as fine aggregate. J Cleaner Prod 112:837–844 2. Hong CW, Lee Jung-Il, Ryu JH (2017) Effect of copper slag as a fine aggregate on the properties of concrete. J Ceram Process Res 18(4):324–328 3. Geetha S, Madhavan S (2017) High performance concrete with copper slag for marine environment. Mater Today: Proc 4(2):3525–3533 4. Ayano T, Sakata K (2000) Durability of concrete with copper slag fine aggregate. Spec Pub 192:141–158 5. Al-Jabri KS, Hisada M, Al-Oraimi SK, Al-Saidy AH (2009) Copper slag as sand replacement for high performance concrete. Cement Concr Compos 31(7):483–488 6. Shi C, Meyer C, Behnood A (2008) Utilization of copper slag in cement and concrete. Resour Conserv Recycl 52(10):1115–1120 7. Al-Jabri KS, Al-Saidy AH, Taha R (2011) Effect of copper slag as a fine aggregate on the properties of cement mortars and concrete. Constr Build Mater 25(2):933–938 8. Sharma R, Khan RA (2017) Sustainable use of copper slag in self compacting concrete containing supplementary cementitious materials. J Clean Prod 151:179–192 9. Brindha D, Nagan S (2011) Durability studies on copper slag admixed concrete

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10. Mithun B, Palankar N (2016) Strength performance of Alkali activated slag concrete with copper slag as fine aggregate exposed to elevated temperatures 11. Ambily PS, Umarani C, Ravisankar K, Prem PR, Bharatkumar BH, Iyer NR (2015) Studies on ultra high performance concrete incorporating copper slag as fine aggregate. Constr Build Mater 77:233–240 12. Abhishek R, Murari K, Singh A, Gangwa S, Copper slag, a solution and an alternative to river sand and in concrete manufacturing. J C 4:562–568 13. Wu W, Zhang W, Ma G (2010) Optimum content of copper slag as a fine aggregate in high strength concrete. Mater Des 31(6):2878–2883 14. Divya Krishnan K, Ravichandran PT, Gandhimathi VK (2017) Experimental study on properties of concrete using ground granulated blast furnace slag and copper slag as a partial replacement for cement and fine aggregate 15. Madhavi TC, Aravind Kumar S (2016) Experimental investigations on compressive strength of copper slag in concrete

Assessment on Performance of Steel Slag and Processed Granulated Blast Furnace Slag as an Alternative for Fine Aggregate—An Assertive Review V. J. Sudarshan, D. Arpitha, Y. T. Thilak Kumar, C. Rajasekaran, and Nagesh Puttaswamy Abstract Sand has always been an integral part of construction in our civilization. It has been the most easily available and acceptable source for the same. However, the depletion of river sand availability has started looking at the alternatives including some industrial by-products. One of them is slag obtained from manufacture/refining of metals which would help in the utilization of industrial waste and conservation of natural resources to have a sustainable construction. This paper provides the gist of organized overview involving the evaluation of physical and chemical characteristics, assessment of mechanical and durability properties for the effective utilization of steel slag and processed granulated blast furnace slag (PGBS) that could be modelled from previous researches related to the study. The basic properties of steel slag and PGBS exhibit requisite properties like river sand which is an indication for a possible alternative material to the conventional aggregate. The multiple processing of slag has its influence on strength, durability, and workability of concrete. These recent innovations have made the slag economically viable and environmentally friendly, and also profitable salvaging of processed by-product. Keywords Sustainable construction · Steel slag · PGBS

V. J. Sudarshan (B) · D. Arpitha · Y. T. Thilak Kumar · C. Rajasekaran Department of Civil Engineering, National Institute of Technology Karnataka, Surathkal, Karnataka, India e-mail: [email protected] D. Arpitha e-mail: [email protected] Y. T. Thilak Kumar e-mail: [email protected] C. Rajasekaran e-mail: [email protected] N. Puttaswamy Ultratech Cement Ltd., Bengaluru, Karnataka, India e-mail: [email protected] © Springer Nature Singapore Pte Ltd. 2021 M. C. Narasimhan et al. (eds.), Trends in Civil Engineering and Challenges for Sustainability, Lecture Notes in Civil Engineering 99, https://doi.org/10.1007/978-981-15-6828-2_21

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1 Introduction Concrete is the primary requirement in the construction industry. Currently, due to fast economic growth, rapid urbanization and the demand for construction increased. Therefore, the need for construction materials like cement, sand, aggregate also increased as well. Fine aggregate is taken from the river bed which is getting depleted and exhausted, and its excessive mining has led to the ecological imbalance. As the raw materials are available from natural resources only, it is a serious threat to the environment and can cause sustainable issues. On the other hand, the cost of the construction materials is growing incrementally. This ecological unevenness has made a circumstance for the general population to concentrate on appropriation of imaginative advancements and environmentally preferable materials, which would not just protect the natural resources yet in addition make a beneficial domain in which human and nature can exist in congruity. To achieve this undertaking, one path is to go for eco-friendly concrete produced using the items that are generated by mining exercises, as waste is unquestionably a decent potential resource. In concern to this background, this study aims at presenting the use of waste material by partial replacing of natural river sand into concrete and checks the feasibility of making concrete and solves environmental problems.

2 Material Properties 2.1 Physical Properties Physical properties obtained conducting experiments and from different authors for steel slag in this study are mentioned in Table 1. According to Devi et al. [1] and Anastasiou et al. [2] steel slag exhibit almost similar physical properties as that of river sand, and according to Satish Kumar et al. (2016) PGBS is used as an ecofriendly alternative to 100% replacement of river sand in construction. Tests were conducted to identify the basic properties of iron slag and PGBS. It is observed that the results fall under the same range as specified in Table 1. Table 1 Physical properties of river sand, steel slag and PGBS Properties

Particle shape

Appearance

Specific gravity

Bulk density g/cc

Fineness modulus

Water absorption

River sand

Irregular

Brownish yellow

2.50–2.81

1.3–1.6

2.58–4.7

1.0–3.0

Steel slag

Irregular

Brownish yellow

2.23–3.00

1.0–1.1

3.21

1.2–2.5

PGBS

Irregular

Brownish yellow

2.55

1.44–1.63

2.34

0.025 mm, Rebound Deflection, D = [2(D0 − Df ) + 5.82(Di − Df )] D0 —Initial dial gauge reading Di —Intermediate dial gauge reading Df —Final dial gauge reading. 2. Correction for temperature: The stiffness of bituminous layers changes with the temperature of the binder and in turn causes the variation in the surface deflection of the pavement. Hence, it is required to correct the measured deflection to a standard temperature. The standard temperature is recommended to be 35 °C or areas having tropical climate. The correction for temperature for the deflection values measured at pavement temperature other than 35 °C should be 0.01 mm for each degree centigrade change from the standard temperature of 35 °C. The correction will be positive for pavement temperature lower than 35 °C and negative for pavement temperature higher than 35 °C. The formula for temperature correction is given by: Standard reference temperature = 35 °C Correction = 0.01 mm/°C Corrected deflection = Measured deflection ± (35 − T )0.01 3. Correction for seasonal variation: Based on the moisture content, rainfall intensity, and plasticity index of soil, appropriate values of seasonal correction factors are obtained from the chart given in IRC:81-1997. The corrected deflection for seasonal variation is calculated by multiplying the correction factor to the measured deflection.

Overlay Design of Flexible Pavements Using …

485

5.2 Traffic Survey The design traffic was estimated in terms of the cumulative number of standard axles (8160 kg) to be carried out by the pavement during design period as per the IRC:81-1997.   365 × A (1 + r )x − 1 × F Design traffic (Ns ) = r Traffic survey was conducted on both the sites, and considering a design life of 10 years, the respective design traffic was obtained: Site 01: The design traffic obtained was 5.81 msa. Site 02: The design traffic obtained was 67.85 msa (Tables 4 and 5). Characteristic Deflection: DC = DM + 2σ for NH and SH DC = DM + σ for other roads Rebound deflections were obtained from Benkelman beam deflection data for site 01 and site 02. Characteristic deflection of about 1.21 and 1.87 mm was obtained after applying the corrections.

6 Overlay Design for Flexible Pavement The overlay for the flexible pavement was determined using the design traffic and the characteristic deflection obtained as per the chart given in IRC:81-1997. The overlay obtained for the pavements was: Site 01: Since the condition of the road is fair, an overlay thickness of 30 mm BC was selected. Site 02: An overlay of 110 mm DBM and 50 mm BC was selected.

7 Results and Analysis As per the IRC: 37-2001, the new pavement composition for the selected sites is (Tables 6 and 7): Tables 8 and 9 show the existing crust and the proposed overlay for sites 01 and 02, respectively. We observed that providing overlay for the two roads was economical compared to the construction of new roads as it involved the provision of just an additional thickness to the existing crust of the roads. The cross section of the roads with the existing crust and the overlay for site 01 and site 02 has been shown in Figs. 6 and 7, respectively (Tables 10 and 11).

0

20

40

60

80

100

120

140

160

180

1

2

3

4

5

6

7

8

9

10

32

34

34

34

34

34

34

32

32

32

3.06

4–91

7–17

4–30

2–9

6–63

1–68

1–35

8–83

2–33

8–88

D0

4–42

6–90

3–81

1–60

6–19

1–44

1–10

8–49

1–56

8–16

Di

4–41

6–86

3–78

1–58

6–16

1–43

1–7

8–45

1–54

8–13

Df

1

0.85

1.21

1.02

0.97

0.5

0.73

0.99

1.58

1.67

1.018

0.868

1.228

1.038

0.988

0.518

0.785

1.045

1.635

1.725

Corrected deflection (mm)

Rebound deflection (mm)

Dial gauge reading (mm)

No of lanes: 1

Moisture content (%)

S. No.

Location of test Pavement points (m) temperature (°C)

Name of the road: Village Road, Nitte

Table 4 Summary of field deflections of site 01

1.085

Mean deflection DM (mm)

0.122

Standard deviation 

1.207

Characteristic deflection DC (mm)

486 A. Prabhu et al.

Dial gauge reading (mm)

80

120

160

2

3

4

5

0

40

80

120

140

6

7

8

9

10

Right lane

0

40

1

Left lane

28

30

30

30

30

30

28

28

28

28

17

2–24

5–57

9–28

9–46

8–92

2–71

3–64

6–48

1–73

9–95

D0

1–73

4–74

8–47

8–75

8–62

2–14

2–97

5–84

1–32

9–78

Di

1–70

4–72

8–40

8–74

8–55

2–08

2–91

5–79

1–21

9–76

Df

1.25

1.7

2.17

1.44

1.15

1.61

1.81

1.67

1.68

0.38

1.31

1.76

2.23

1.50

1.21

1.69

1.89

1.75

1.76

0.46

Corrected deflection (mm)

Rebound deflection (mm)

Moisture content (%)

S. No.

Location of test Pavement points (m) temperature (°C)

No of lanes: 2

Name of the road: Hosmar SH 37

Table 5 Summary of field deflections of site 02

1.55

Mean deflection DM (mm)

0.16

Standard deviation σ

1.87

Characteristic deflection DC (mm)

Overlay Design of Flexible Pavements Using … 487

488 Table 6 Pavement composition of site 01 (As per IRC:37-2001)

A. Prabhu et al. Pavement composition

Allowable thickness

Granular sub-base (GSB)

150 mm

Granular base (WBM)

250 mm

Bituminous surfacing

Table 7 Pavement composition of site 02 (As per IRC:37-2001)

Wearing course (SDBC)

25 mm

Binding course (DBM)

50 mm

Pavement composition

Allowable thickness

Granular sub-base

335 mm

Granular base

255 mm

Bituminous surfacing

Table 8 Existing crust and proposed overlay for site 01

Table 9 Existing crust and proposed overlay for site 02

Wearing course (BC)

40 mm

Binding course (DBM)

160 mm

Existing crust

Proposed overlay for the existing crust

GSB-100 mm WBM-150 mm Total-250 mm

BC-30 mm

Existing crust

Proposed overlay for the existing crust

GSB-100 mm WMM-150 mm BM-50 mm SDBC-25 mm Total-325 mm

DBM-110 mm BC-50 mm Total-160 mm

Fig. 6 Pavement composition with the proposed overlay for site 01

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Fig. 7 Pavement composition with the proposed overlay for site 02

Table 10 New proposed road as per PWD

New proposed road GSB-150 mm WBM-200 mm BM-50 mm SDBC-25 mm Total-425 mm

Since the reconstruction of the pavement includes excavation and addition of extra layers of GSB and WBM, the introduction of overlay would be more economical when compared to a new pavement.

8 Conclusions • Compaction values obtained for site 01 and site 02 were 21.78 kN/m3 (OMC11.45%) and 19.62 kN/m3 (OMC-12.68%), respectively. • Soaked CBR values obtained for site 01 and site 02 were 8.79% and 4.18%, respectively. • 5.81 msa and 67.85 msa were the respective design traffic data obtained for site 01 and site 02. • Based on the Benkelman beam deflection data and the design traffic obtained, the overlay proposed for site 01 was 30 mm BC and for site 02 was 110 mm DBM and 50 mm BC. • Based on the cost estimation of the roads, we observe that cost of building a new road is more than the cost of overlay for both the roads. There was a cost reduction of Rs. 5,911,224 for the village road in Nitte and Rs. 7,651,260 for SH 37 Hosmar road. So it is economical to provide overlay.

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Table 11 Cost estimation for site 01 and site 02 Particulars

Quantity

Rate

Total cost of construction of road

New road as per IRC:37-2001 for village road in Nitte GSB

825

1672

1,379,400

WBM

1375

1868

2,568,500

DBM

275

9000

2,475,000

SDBC

137.5

7678.72

1,055,824

Total

Rs. 7,478,724

Proposed overlay for village road in Nitte BC

165

9500

Rs. 1,567,500

New road as per IRC:37-2001 for SH 37 Hosmar GSB

1842

1672

3,079,824

WBM

1402

1868

2,618,936

DBM

880

9000

7,920,000

SDBC

220

9500

2,090,000

Total

Rs. 15,708,760

Proposed overlay for SH 37 Hosmar DBM

605

9000

5,445,000

BC

275

9500

2,612,500

Total

Rs. 8,057,500

Proposed road as per PWD for SH 37 Hosmar GSB

825

1672

1,379,532

WBM

1100

1868

2,054,800

BM

275

5990

1,647,250

SDBC

137.5

7678.72

1,055,824

Total

Rs. 6,137,406

• Periodic maintenance of the roads at an early onset of distresses can reduce maintenance expenditure. • BBD method is one of the most simple, inexpensive and reliable methods for deflection measurement of pavements.

References 1. Mayank GB, Vankar A, Zala LB (2013) Structural evaluation using Benkelman beam deflection technique and rehabilitation of flexible pavement for state highway 188 (Sarsa junction to Vasad junction). J Int Acad Res Multidisciplinary 1(4) 2. Sharma U (2014) Non-destructive of an internal road of Chandigarh—a critical case study. In: International conference on biological, civil and environmental engineering (BCEE-2014), Mar

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17–18, 2014, Dubai (UAE) 3. Yousuf N, Khan MH (2015) Strengthening of flexible pavement through Benkelman Beam Deflection (BBD) technique. Int J Res Eng Technol 3(10) 4. Kumar MK, Gouse Peera D, Praveen Kumar K (2015) A study on overlay design of repeatedly deteriorating flexible pavement. Am J Eng Res (AJER) 4(6):46–51 5. Umersalam, Bhasir A, Mir MS, Rashid T (2015) Evaluation and strengthening of reconstructed roads excavated for utilities using Benkelman Beam Deflection (BBD) technique (a case study). Int J Civ Eng Technol 6(1):27–38 6. Bhimani S, Shinkar PA, Mathakiya AM (2017) Performance evaluation of pavements: a case study on Kankot-Mavdi road. IJSRD Int J Sci Res Dev 5(02) 7. Subramanyam B, Aravind S, Prasanna Kumar R (2017) Functional and structural evaluation pf a road pavement. Int J Civ Eng Technol (IJCIET) 8(8):1299–1305 8. Mehta H (2018) Functional evaluation and overlay design of existing flexible pavement: a case study of Karni &Khara industrial area road in Bikaner. SSRG Int J Civ Eng (SSRG-IJCE) 5(3)

Environmental Engineering and Water Resource Engineering

Anaerobic Co-digestion of 2,4-Dichlorophenoxyacetic Acid with Starch Followed by Aerobic Post-treatment and Identification of Dominant Bacteria G. B. Mahesh and Basavaraju Manu Abstract This study was conducted to investigate the new method comprising of sequential anaerobic followed by aerobic batch reactor treatment for 2,4dichlorophenoxyacetic acid (2,4-D). The various parameters influencing on the anaerobic digestion like pH, temperature, oxidation reduction potential (ORP) have been monitored during the 60 days study period. pH range of 6.5–7.2, temperature greater than 31.4 °C and ORP values between −250 and −300 mV have reported better reactor performance with high 2,4-D removal and biogas production. The complete biotransformation of 2,4-D in the anaerobic reactor is indicated by disappearance of intensity peak in the high-performance liquid chromatograph (HPLC) report, high biogas production of 12–18% than control and COD removal efficiency of 99%. Dominant bacterial community in the sludge was identified using SEM images. The results of this study indicate that anaerobic reactor and aerobic post-treatment method can make the treatment highly efficient. Keywords 2,4-d · Anaerobic co-digestion · Aerobic mineralisation · Biotransformation

1 Introduction 2,4-dichlorophenoxyacetic acid (2,4-D) is considered to be most commonly used herbicide worldwide, and its presence is detected in the agricultural run-off water up to 25 mg/L [1] and up to 500 mg/L in industrial effluent [2]. The run-off water joining the downstream water bodies makes pollution of both surface and groundwater. The toxicity risk to non-target plants and also to other living organisms is potentially high. Sequencing batch reactors (SBRs) are considered to be simple, flexible and G. B. Mahesh (B) · B. Manu Civil Engineering Department, NITK, Surathkal, Mangaluru, India e-mail: [email protected] B. Manu e-mail: [email protected] © Springer Nature Singapore Pte Ltd. 2021 M. C. Narasimhan et al. (eds.), Trends in Civil Engineering and Challenges for Sustainability, Lecture Notes in Civil Engineering 99, https://doi.org/10.1007/978-981-15-6828-2_37

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cost-effective biological wastewater treatment techniques. The SBRs are widely used in the treatment of small-scale wastewater generated from industrial and domestic activities and can be operated in anaerobic, anoxic and aerobic condition. Anaerobic SBRs (ASBR) have also proven to be efficient in the treatment of various industrial effluents having high concentrations of organic matter [3, 4]. The ASBR help in the breakdown of 2,4-D through dehalogenation and demethylation reactions [5]. The aerobic reactor functions as polishing step to anaerobic effluents [6] and supports the mineralisation of anaerobic transformation products. The anaerobic treatment has been regarded as one of the most promising options for increasing biogas production because of its better nutrient balance and improved efficiency [7]. Anaerobic treatment processes are environmental sensitive and can be influenced by operational parameters easily. Operational parameters which improve the anaerobic digestion efficiency are the temperature, pH, carbon to nitrogen (C/N) ratios, mixing ratios, additives and other parameters. Alkalinity is a better indicator of process performance and directly shows the system’s buffering capacity. Alkalinity is being maintained in the reactor by providing sodium bicarbonate (NaHCO3 ) as buffer with pH of 8 to maintain the reactor pH in the neutral range 6.5–7.3 as required for the methanogenic bacteria [8] and pH maintenance will also influence on the stability of the process. It has been reported that operational conditions could influence process parameters like alkalinity, pH, organic degradability, volatile fatty acids (VFA) and further impact on methane production rate. Anaerobic sequential batch reactors (ASBR) have been used in the treatment of wastewaters polluted with various types of organic pollutants. Use of ASBR in the treatment of herbicide containing water is rarely reported in the literature. The influencing parameters on the performance of the anaerobic and aerobic reactors during co-digestion of organic pollutants have been understudied. Thus, sequential anaerobic–aerobic treatment technique is considered as an efficient alternative method to mineralise the metabolites of herbicides and our previous study reported such observations [9]. Therefore, the objectives of this study were mainly to evaluate the influence of various operating parameters on the performance of ASBR and to treat simulated agriculture run-off water containing 2,4-D with starch in anaerobic followed by aerobic reactor and to identify the dominant bacteria in the sludge.

2 Materials and Methods 2.1 Reactor Seeding The seed sludge was collected from the discharge point of an up flow anaerobic sludge blanket unit and characterised for mixed liquor suspended solids (MLSS) and mixed liquor volatile suspended solids (MLVSS). Aerobic seed sludge was collected from the recycle unit of an activated sludge process (ASP) reactor. The anaerobic

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reactors were inoculated with 9000 mg/L of MLVSS of anaerobic sludge, and aerobic reactors were inoculated with aerobic seed sludge having 3000 mg/L of MLVSS.

2.2 Reactor Set-up and Operation This preliminary study consisted of two sets of anaerobic and aerobic SBR (one of each anaerobic and aerobic reactor as control) as shown in Fig. 1. Anaerobic digestion was carried out in a reactor having a capacity of 2.5 L (operating capacity is 2 L) glass bottle connected to a liquid displacement system to collect the gas production. Aerobic reactor has a capacity of 2.5 L (operating capacity is 2 L) fitted with an air diffuser to maintain required dissolved oxygen level of 3–4 mg/L. Anaerobic control reactor is named as (AnR1), anaerobic reactor treating 2,4-D as (AnR2), aerobic control as (AR1) and aerobic reactor treating 2,4-d as (AR2). Anaerobic reactors were inoculated with 9000 mg/L of anaerobic seed sludge, and aerobic reactor was seeded with 3000 mg/L of aerobic seed sludge. The anaerobic

Fig. 1 Schematic diagram of anaerobic and aerobic reactor

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reactors were operated in batch mode by feeding and decanting 1 L of water, feed water contained 1 g/L of starch, 2 g/L of sodium bicarbonate (NaHCO3 ) for 14 days. After observing the stable bacterial activity, the dosage of starch and NaHCO3 was increased twofold to enhance the biomass activity. Bacterial activity was measured in terms of CH4 production, COD removal and rise in the biomass concentration in the reactor. The methane gas production was recorded as the amount of potassium hydroxide (KOH) displaced in the gas–liquid displacement system. The aerobic reactors were operated with anaerobic effluent as feed by decanting 0.5 L supernatant water. The reactors were allowed to react for 24 h after each fresh feed, and during the treatment process gas production is recorded in each anaerobic reactor by allowing the gas–liquid displacement system. The anaerobic reactors have attained steady-state condition after 16 days by yielding a constant COD removal efficiency of 82% for three consecutive days, similarly aerobic reactors attained steady-state condition after 12 days of operation. Then, the experimental anaerobic reactor (AnR2) was fed with simulated water containing 25 mg/L of 2,4-D along with starch for 30 days.

2.3 Analytical Methods The anaerobic intermediate compounds of 2,4-D are traced in liquid chromatograph mass spectroscopy (LC-MS) (Shimadzu—2020). 2,4-D in the effluent was measured using high-performance liquid chromatography (HPLC) (Agilent, 1260) as per the HPLC method developed [1]. Volatile fatty acids (VFAs) were determined using GC–FID (Thermo Scientific, Trace1110). Microbial morphology was studied using scanning electron microscopy (SEM, Jeol make) and dissolved oxygen using DO meter (HI 9147, Henna Instruments), pH and temperature using portable meters (edge, Henna Instruments). The mixed liquor suspended solids (MLSS), mixed liquor volatile suspended solids (MLVSS), alkalinity and chemical oxygen demand (COD) are determined using standard methods [10]. Reactor sludge was also characterised to find out herbicide adsorption following the procedure mentioned [11]. VFA determination: All the samples were diluted ten times using deionized water. Ten mL sample was vortexed along with 10 mL of methyl-tert-butyl ether (MTBE) for approximately 10 min. The supernatant organic phase was transferred quantitatively to a dry beaker and dried using anhydrous magnesium sulphate. The extract was filtered, and 1 µL was injected into the GC. GC method includes carrier gas: helium; flow rate: 1 mL/min; initial oven temperature: 35 °C and raised to 240 °C at 10 °C/min, auxiliary temperature: 230 °C, run time: 28 min.

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3 Results and Discussion 3.1 Anaerobic Treatment of 2,4-D The influent to anaerobic reactor was prepared by dissolving 2 g/L of starch to yield chemical to yield COD of around 2200 mg/L. Performance of anaerobic reactors during the 16 days of acclimatisation period with starch as primary carbon source was found to be stable. It can be observed that more than 82% COD removal and CH4 gas yield of 300 mL/day indicate complete anaerobic digestion of starch by the inoculated biomass in both the reactors. It indicates that the reactors have attained quasi-steady-state condition. The process parameters are observed to be stable and within the required range for an anaerobic digestion process. Both the control (AnR1) and experimental (AnR2) reactors performed similar to each other during start-up period, and influence of temperature is observed to be greatly affecting the reactor performance. MLVSS was found to be 9500 mg/L on the 16th day of initial operation before herbicide introduction. The anaerobic reactor stabilization was achieved in 28 days with consistent COD removal efficiency of 82%, and observing all the other parameters at stable condition, similar results were reported in our previous study [9]. From day 30 onwards, 25 mg/L of 2,4-D was introduced to the experimental reactor (AnR2). The comparative analysis of COD removal efficiency in control and experimental along with 2,4-D degradation efficiency is depicted in Fig. 2. Methane gas production in the AnR2 was observed to be greater than 14–18% of the AnR1. It can be observed that there was a drop in COD removal efficiency and total gas yield corresponding to reduced MLVSS (1000 mg/L in the effluent [12].

Fig. 2 Herbicide removal efficiency and comparison of COD removal efficiency of AnR1 and AnR2

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Fig. 3 Comparison of total biogas produced in both anaerobic reactors

After 8 days of lag phase, MLVSS concentration recovered due to increased biological activity. Increased CH4 gas yield and COD reduction may be due to increased biomass concentration in the reactor over the time (Fig. 3). It was observed that 100% herbicide biotransformation was achieved on 18th day of treatment with COD removal of 75%. [13] have reported 65% COD removal for complete removal of 130 mg/L of 2,4-D at 48 h HRT using glucose as carbon source. VFA in the AnR1 was observed to be 1000 mg/L), high COD levels in the AnR2 may be due to VFA accumulation, and similar observations were reported in the literature [14]. HPLC obtained for the influent and effluent samples indicates the formation of intermediates of 2,4-D in the effluent sample with the appearance of different peaks. Then, the samples were analysed in the LC–MS to track the metabolites, and some of the major transformation products are identified as esters and different fatty acid groups. HPLC results obtained for sludge extracted liquid samples did not show intensity peak and indicate 2,4-D was not adsorbed onto the reactor sludge.

3.2 Stability Analysis of the System 1. pH, alkalinity, temperature and ORP pH and alkalinity varied fairly stable during the initial period of operation (before introducing 2,4-D) and are at required level for an anaerobic digestion process. After introducing 2,4-D to AnR2, the pH was reduced to 6.2 and the alkalinity reported >2900 mg-CaCO3 /L. pH was then increased and was in between 6.5 and 7.3, which was considered suitable for anaerobic methanogenic digestion process [8]. Low pH < 6.5–6.2 observed during the initial days of operation may be due to the acidogenic condition of the reactor. The anaerobic reactors mainly buffered to maintain the required pH level. Ambient temperature was recorded

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Fig. 4 ORP recorded during the treatment process in both the anaerobic reactors

regularly and was reported between 28 ± 0.5 and 31 ± 0.5 °C, and ORP was observed in the range of −250 to −300 mV. The digestion process is considered to be highly efficient at high temperature and low ORP ranges. As the negative ORP indicates reductive biochemical activity in anaerobic reactor supported by the added substrates, ORP of AnR2 was observed to be much lower than the AnR1 (Fig. 4). Lower ORP than the control may suggest greater potential of 2,4D being acted as electron acceptor, starch as electron donor and thus transformed to fatty acids under reducing reactions [15].

3.3 Aerobic Post-Treatment of 2,4-D Metabolites Post-treatment of anaerobic effluents in the subsequent aerobic reactor was conducted to enhance the system efficiency, and the performance of AR1 and AR2 is shown in Fig. 5. Complete degradation 2,4-D metabolites within the 12 days of operation was observed, which is supported by the maximum COD removal efficiency (>99%). The

Fig. 5 Performance of AR2 compared with AR1

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degradation pattern followed a similar trend as observed during treatment before 2,4D introduction. [16] have reported that aerobic reactor removed 500 mg/L of 2,4-D at 48 h HRT during 185 days of operation. In this study, the aerobic reactor acted as a polishing step, which completely mineralised the 2,4-D transformation products within 10 days at 24 h HRT. No VFA compounds have been detected in the aerobic effluent was observed in GC analysis. HPLC report obtained for the aerobic effluent shows no formation of intensity peaks at retention time of 9.57 min, which supports the disappearance of compound. The DO in the reactor was observed to be 2–3.5 mg/L and at this level the maximum COD removal was observed. Maximum COD removal may indicate the degradation of organic compounds in the reactor [12]. Alkalinity was found to be SO4 > HCO3 > NO3 with chloride dominance among anions indicating the saline water ingression in the study area with salinity hazard in soils. Irrigation quality is based on sodium absorption ratio (SAR), percentage sodium (%Na) and permeability index (PI) (Table 3) values which were calculated by formulae. Sodium adsorption ratio (SAR) is one of the tools for checking water suitability for irrigation purposes. The excess sodium in water will reduce the soil permeability and infiltration rate by blocking the pores in soil [7]. SAR is calculated by formula: SAR =   1 2

Na+ Ca2+ + Mg2+



The SAR values of water samples from Lake 4 and the open well are 27.6 meq/l and 27.3 meq/l respectively. SAR value greater than 26 meq/l can indicate high sodium hazards and is unsuitable for irrigation purposes [8]. Percentage Sodium (%Na) is a parameter for irrigation purpose since it causes clogging of particles and reduces the permeability of water and gases [9]. Maximum of 60% sodium is recommended for irrigation as per Bureau of Indian Standards [5]. Percentage Sodium ranges from 94.7 to 98.1% which can be attributed to the saline water ingression in this area. Permeability Index (PI) developed by Doneen [10] indicates the suitability of groundwater for irrigation. Soil permeability is affected by continuous irrigation and is influenced by calcium, sodium, magnesium and bicarbonate contents of the soil. The PI value of samples from the study area falls in Class III type with maximum permeability of 25% (Fig. 3). The US Salinity Laboratory (USSL) classification diagram is plotted (Fig. 4) in which SAR is taken as alkalinity hazard and EC is taken as salinity hazard. Lakes 1, 2 and 3 fall under C2S1 suggesting medium salinity hazard and low sodium hazard; whereas Lake 4 falls under C4S4 suggesting very high hazards of both salinity and

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Fig. 3 Doneen’s (1964) diagram indicating study area’s water suitability for irrigation

Fig. 4 USSL classifications of water samples

sodium. Water sample of open well falls under C3S4 suggesting high salinity hazard and very high sodium hazard. In Wilcox [12] diagram (Fig. 5), EC to % Na shows Lakes 1, 2 and 3 fall under doubtful to unsuitable category, whereas Lake 4 and open well fall under unsuitable. Piper (1953) Tri-linear classification [11] is used for hydrogeochemical facies of cation and anion. The Piper (1953) Tri-linear classification diagram has been drawn (Fig. 6) using AquaChem 2011.1 software. From the Piper diagram, it is observed

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Fig. 5 Wilcox diagram of water samples

Fig. 6 Piper diagram for water samples

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that L2, L3, L4 and OW fall in the Na–Cl field indicating strong sea water influence in these samples.

4 Conclusions • The analysis shows that the water bodies are progressively more contaminated downstream, and in the lower reaches (open well and L4), it is severely contaminated with saline water indicating that the frequency of ingression is more in these areas close to the Nethravathi River. • Hydrogeochemical analysis shows the precedence of Na+ > Mg2+ > K+ > Ca2+ : Cl− > SO4 2− > HCO3 > NO3 indicating the influence of saline water ingression in the study area. • USSL, Wilcox and Piper diagrams also clearly indicate saline water ingression and the contamination of water sources. • The values of EC, TDS, SAR and %Na indicate the contamination of water sources and their unsuitability for irrigation. • Prevention and control of saline water ingression can be achieved in this area by harvesting the rain water in the upstream catchment area with proper planning and management of water resources. • Construction of check dams with appropriate height on the downstream side of the area can prevent the tidal bore of saline water in the summer seasons and contamination of surface water bodies there. • By adopting proper foundation techniques and construction techniques, development activities can be carried out in the proposed area. Acknowledgements The authors are thankful to the Management of Nitte Education Trust (Regd.), Nitte University and NMAM Institute of Technology for the support and encouragement extended.

References 1. CGWB (2017) Groundwater information booklet-Dakshina Kannada. Government of IndiaMinistry of Water Resources, Nov 2009. Retrieved 6 Oct 2017 2. APHA (1995 & 1998) Standard methods for the analysis of water and waste water, 20th edn. American Public Health Association, Washington DC 3. Radhakrishnan K, Narayana SK, Lokesh KN (2011) Hydrogeochemical studies of groundwater along the coastal region of Mulki-Udupi, Karnataka State, India. Int J Earth Sci Eng 4(7-Spl Issue):333–339. Cafet-Innova Technical Society, Hyderabad 4. WHO (1993) Guidelines for drinking water quality, 2nd edn., vol 1. World Health Organization, Geneva, 188 p 5. BIS (2012) Indian Standard specification for drinking water. Bureau of Indian Standards–IS: 10500: 2012, Government of India, Calcutta

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6. Mondal P, Majumder CB, Mohanty B (2008) Effect of adsorbant dose, its particle size and initial arsenic concentration on the removal of arsenic, iron and manganese from simulated groundwater by Fe3+ impregnated activated carbon. J Hazard Mater 150:695–702 7. Subba RN, Surya RP, Venktram RG, Nagamani M, Vidhyasagar G, Satynarayana NLV (2012) Chemical characteristics of groundwater and assessment of groundwater quality in Varaha River Basin, Visakhapatanam District, Andhrapradesh, India. Environ Monit Assess 184:5189–5214 8. Richards LA (1954) Diagnosis and improvement of saline and alkali soils. In: Agricultural handbook: 60. U.S. Department of Agriculture, Washington D.C., 160 p 9. Todd DK. Ground water hydrology. Wiley, New York, 190 p 10. Doneen LD (1964) Notes on water quality in agriculture 11. Piper AM (1953) A graphical procedure in the chemical interpretation of groundwater analysis. USGS groundwater note, no 12, 63 p 12. Wilcox LV (1955) Classification and use of irrigation water. U.S. Department of Agriculture circular 969, Washington D.C., USA

Assessment of Solar Power Potential Mapping in Telangana State Using GIS Manish S. Dharek, Prashant C. Sunagar, Manjunath V. Kadalli, K. S. Sreekeshava, and Anant G. Pujar

Abstract Solar energy replacing conservative non-renewable energy is being witnessed in often around the world. Solar energy has a massive prospective in a humid country like India. Most parts of the country get around 300 sunshiny days in a year with 8 h of daily sunlight. Presently, one of the most interesting problems is how to mend the effectiveness of generating solar energy. Before installing solar panels, evaluating where solar panels should be positioned can considerably benefit panel performance. The present study is aimed at carrying out site selection analysis for setting up of solar panel using geographic information system (GIS). Telangana is a state which ranks fourth in terms of capacity to harness and utilize solar energy. The project is aimed at mapping the areas with high solar energy potential at both macroand micro-levels. The solar irradiation data (GHI and DNI), land use data and digital elevation model (DEM) have been used in GIS environment while retaining land use criteria and topography to omit unsuitable sites for harnessing solar energy. The study carried out concludes total suitable area of 11,520.60 km2 at macro-analysis for economical and effective harnessing of solar power. Keyword Geographic information systems · Solar energy potential · Site selection analysis M. S. Dharek (B) · M. V. Kadalli Department of Civil Engineering, BMSIT&M, Bengaluru, India e-mail: [email protected] M. V. Kadalli e-mail: [email protected] P. C. Sunagar Department of Civil Engineering, Ramaiah Institute of Technology, Bengaluru, Karnataka, India e-mail: [email protected] K. S. Sreekeshava · A. G. Pujar Department of Civil Engineering, Jyothy Institute of Technology, Bengaluru, India e-mail: [email protected] A. G. Pujar e-mail: [email protected] © Springer Nature Singapore Pte Ltd. 2021 M. C. Narasimhan et al. (eds.), Trends in Civil Engineering and Challenges for Sustainability, Lecture Notes in Civil Engineering 99, https://doi.org/10.1007/978-981-15-6828-2_63

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1 Introduction The daily energy requirement is increasing at faster rate by all the populace across world. The necessity for energy has seen a sharp increase and its linked facilities to gratify human social and economic development, as well as welfare. Above events have led to over-exploitation and extreme use of non-renewable resources, as seen through fossil fuel-based power generation, for example, the ever-growing demand for petrol production. In addition, depletion of non-renewable sources has elevated the energy crisis. Serious impacts can still be evaded if efforts are made to transform current energy systems. Solar energy is genesis for all forms of energy. This energy is used in two ways, first, in thermal route where heat medium is used to generate power in different forms, and, second, photovoltaic route which converts solar energy into electricity. Switching to solar energy helps to cut down the major ill effects on earth, for instance, the pollution caused from CO2 [1]. Majority of energy consumption is associated with solar sources, and hence, the focus is increasing on extracting this efficient source of energy through improved technology. In our project, we have found easier ways to transform energy content on a large scale to meet consumer demands. Incorporating geographic information systems with data collected, we have depicted results by working through objectives of plan for Telangana state. This paper includes the methodology of analyzing potential energy using GIS and illustrates this for Telangana state of India.

2 Literature Review Joshi et al. [2] demonstrated monthly solar mapping developed in GIS environment by input of the location and solar irradiation value in polygon format for Uttarakhand state. Solar mapping was developed using MapInfo and linking information about RE with the databases for individual district. SQL queries were used to retrieve the data from database. They also concluded that entire state receives solar radiation of about 3–6.5 kWh/m2 /day and this map can be helpful in formulating new facilities to utilize the solar energy. Moreover, they suggests that GIS can be used to exploit the advantages of terrain and topographic features of Uttarakhand with the help of government leaders by initiating new facilities to be instated. Wang et al. [3] explained spatial planning for renewable energy using pre-planned procedure at the regional level utilizing concept of GIS. Potential sites are selected according to geographic characteristics. Energy density mapping was executed to find out the potential areas having self-sufficiency in terms of renewable energy. The criteria to select sites are non-urbanized areas in urbanized areas and having minimum land area of 1.5 Ha and excluding built-up areas, agricultural lands, commercial and public spaces. The terrain slope considered is up to 2.5% and aspect of 2.5–15% to face south. They concluded that among available renewable energy potential sources, solar power

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has the maximum theoretic potential among all the five RES. Ramachandra et al. [4, 5] discussed the application of geographic information system (GIS) to map the renewable energy potential in Karnataka. Global solar radiation was calculated by compiled data from stations which were used unswervingly and for locations where the data was not obtainable, indirect methods were used. Their study concluded that global solar radiation during monsoon is less compared to summer and winter because of the dense cloud cover. The study identifies that coastal parts of Karnataka with the higher global solar radiation are ideally suited for harvesting solar energy.

3 Objectives • To prepare the solar radiation map with interpretation of solar irradiance data • To prepare the mapping for optimum site selection using geographic information system (GIS). Furthermore, there are few specific reasons why Telangana is our study area, as it is fourth highest producer of solar energy in India with a figure of reaching 1287 kw of capacity. Second, Telangana has a vast solar potential with average solar insolation of nearly 5.5 kWh/m2 for more than 300 sunny days. Government of Telangana state intends to substantially use this potential energy for major power generation.

4 Data Collected Datasets collected include solar radiation data, Land Use and Land Cover information and digital elevation model (DEM) for macro-analysis. Aerial imagery of good resolution from Google Earth Pro software has been derived. Other datasets include Telangana State Boundary, etc. Data used in study is summarized in Table 1. Table 1 Datasets collected to model the solar maps Sl. No.

Data

Source

Format

1.

Global Horizontal Irradiation (GHI)

Global Weather Data

Excel Sheet File (.xls)

2.

Terrain Slope And Aspect

Bhuvan, India (Geo-Platform of ISRO)

GeoTIFF

3.

Land Use and Land Cover

Bhuvan, India (Geo-Platform of ISRO)

GeoTIFF

4.

Telangana State Boundary

DataMeet Web site

Shapefile

5.

Malepally Ward Boundary

DataMeet Web site

Shapefile

6.

Aerial Satellite Image

Google Earth Pro

–

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Solar irradiance data was derived from National Centers for Environmental Prediction (NCEP) online data repository for the period of July 2013 to June 2014. Land Use and Land Cover data is collected from Oak Ridge National Laboratory (ORNL) Distributed Active Archive Centre (DAAC) managed by NASA. The data is at 100-m resolution for India at decadal period from 1985-01-01 to 2005-12-31. Land Use and Land Cover map describes the vegetation, water, natural surface and cultural features on land surface.

5 Features Considered for Analysis of Solar Panels 5.1 Amount of Incoming Solar Radiation The average level of sun exposure determines solar radiation striking a specific location on Earth’s surface. Solar radiation greater than 5kWh/m2 is considered to be economical for the project.

5.2 Shadow Impacts Ideal performance of PV panels is easily affected by physical factors, such as surface orientation, land surface gradient, adjacent obstacles which can have significant impact by causing shadow effects. The relative angular position of sun throughout the day and year should be considered to decide the appropriate orientation. Summer in northern hemisphere coincides with the northern hemisphere being more oriented toward the sun, which causes solar rays to strike the ground more directly. Therefore, a southern exposure is generally optimal for obtaining the strongest intensity of sunlight in northern hemisphere.

5.3 Land Restricting Factor Identification of land cover establishes the baseline information for activities like thematic mapping of solar power potential analysis. Installations of solar panel should be situated away from aquatic sources and coastline zones to reduce risk of water pollution from PV construction contamination. Similarly, classification of land use helps us to determine different available and optimum sites. Barren land, waste land, fallow land and shrub land are incorporated as suitable land.

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5.4 Other Factors Losses due to transmission and distance of solar installation to substations have to consider to improve PV system performance. Factors affecting site selection are given in Table 2.

6 Methodology To develop a process for solar panel placement site selection, diverse methods were used for macro-scale levels of study. First, monthly and yearly accumulated solar radiation maps, slope map and Land Use and Land Cover (LULC) map [6] were generated to assist site selection for macro-scales. A multi-criteria analysis (MCA) approach has been adopted at macro-scale level. The general methodology for analysis of solar energy framework using GIS approach is summarized in flowchart in Fig. 1. Table 2 Factors affecting optimum site selection Sl. No.

Criteria

1.

Slope

Slope limit is less than 4%

2.

Aspect

Southeast to southwest facing orientation only

3.

GHI

Equal to or greater than 5 KWh/m2 /year

4.

Land suitability

Shrub land, barren land, waste land, fallow land and grassland

Fig. 1 Flowchart explaining the methodology adopted

Standard and restriction

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6.1 Analysis As discussed above about macro-analysis, the following are brief steps for solar power potential mapping. • STEP 1: Creating a solar irradiation map, slope map, Land Use and Land Cover map • STEP 2: Extracting unsuitability factor for each map according to criteria selected • STEP 3: Modeling and overlaying all extracted maps to obtain optimum site for solar PV system.

6.2 Solar Irradiation Map Using Inverse Weighted Distance Tool in ArcMap 10.3, we form solar heat maps of both monthly and yearly mean. Figures 2, 3 and 4 show the monthly solar heat maps, and Fig. 5 displays the mean annual solar heat map.

6.3 Slope Map Digital elevation model (DEM) [7] is used to create slope map. Mosaic tool, fill tool and slope tools are used to get the figurative slope map of Telangana as seen in Fig. 6.

6.4 LULC Map LULC map is needed to identify the sites to install the solar panels, so it is necessary to classify the land and identify built-up land, cropland, forest land, water bodies, etc., to exclude them. Extraction by mask is used to remove the Telangana state characteristics from India’s LULC map. Figure 7 shows LULC map of Telangana as per year 2005.

6.5 Extraction of Solar Irradiation Map Using Less Than tool and Set Null tool, we erase sites having solar radiation less than 5 kWh/m2 . Figure 8 displays areas having radiation more than 5 kWh/m2 .

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Fig. 2 Monthly radiation maps, July 2003

6.6 Extraction of Slope Map Flat terrain is vital for solar exposure and constructability, while a high daily annual solar irradiance is needed for plant efficiency and stability. For economical site selection, slope should be less than 4% (2.29°). By using Greater Than tool and Set Null tool, we erase unsuitable areas from map. Figure 9 shows us that most of land is available for panel installation.

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Fig. 3 Monthly radiation maps, August 2003, September, October, November 2013 (left, middle, right)

Fig. 4 Mean annual solar heat map

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Fig. 5 Slope map of Telangana state

6.7 Extraction of LULC Map Equal To tool and Set Null tool help to remove areas where there are built-up structures, water bodies, croplands, forest land, etc. Figure 10 displays feasible distributed areas around the state.

6.8 Extraction of LULC Map Combining all three extracted maps helps to find the most feasible and optimum site for ground mount panels or retrofitted panels, based on financial viability. Fuzzy overlay tool is used to overlay all three maps to obtain an optimum site map as seen in Fig. 11.

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Fig. 6 Land use and land cover map of Telangana

7 Results and Discussion The PV site suitability model and map product define the areas that satisfy the technical, economical and environmental goals of this study. The study shows Telangana received Global Horizontal Irradiance (GHI) in the range as displayed in Table 3. The dark red-colored areas represent high intensity of solar radiation in Fig. 11, whereas green-colored areas indicate least intensity of solar radiation. Total area of Telangana state is 112,077 km2 , out of which suitable area to be found out was 11,520.6 km2 . Nalgonda District has more annual solar power potential.

8 Conclusion Based on the following results, conclusions are as follows. • Feasible area available for solar energy is harvested on waste, barren and unutilized lands of Telangana state.

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Fig. 7 Map of solar radiation more than 5 kWh/m2 in Telangana

• The total feasible area found at macro-level is 11,520 km2 , where we can install solar panels to generate electricity profitably. This area is distributed all around in Telangana state, while the installation of a solar park has to be done in concentrated area. Nalgonda region has met the requirements, and the area can be used for maximum advantage to build solar parks. • This project can be undertaken by Government of Telangana to further advance the decision making and provide the area with maximum solar exposure.

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Fig. 8 Map of Telangana having slope less than 4% (2.29°)

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Fig. 9 Map indicating areas where solar panels can be installed in Telangana for maximum output

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Fig. 10 Overlay map of the annual solar heat map, extracted slope map and extracted LULC map

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Fig. 11 Map showing areas where solar parks can be set up

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880 Table 3 Monthly irradiance values (kWH/m2 )

M. S. Dharek et al. Month

Irradiation values

January

5.1

February

5.68

March

5.9

April

6.57

May

6.18

June

5.56

July

3.21

August

4.47

September

5.53

October

4.84

November

4.92

December

5.08

References 1. Singh A, Madhava C, Kapoor K, Kadali M (2018) Assessment of solar power potential mapping of Telangana state using GIS. UG Thesis, Department of Civil Engineering, BMSIT&M, Bengaluru 2. Joshi J (2013) A research study on developing solar potential map using GIS 2(3). www.ijettcs 3. Wang Q, M’Ikiugu MM, Kinoshita I (2014) A GIS-based approach in support of spatial planning for renewable energy: a case study of Fukushima, Japan. Sustainability 6:2087–2117 4. Ramachandra TV (2007) Solar energy potential assessment using GIS. Energy Educ Sci Technol 18(2):101–114 5. Ramachandra TV, Jha RK, Krishna SV, Shruthi BV (2005) Solar energy decision support system. Int J Sust Energy 24:207–224 6. Reddy Anji (2014) Text book on remote sensing and GIS, III edn. B S Publications, Hyderabad 7. Manugula SS (2017) Photogrammetry, GIS & remote sensing, I edn. ebooks2go publications, Hyderabad