Bridge engineering [2 ed.] 9780070656956, 0070656959

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Bridge Engineering Second Edition

Bridge Engineering Second Edition

S Ponnuswamy

Copyright © 2007. Tata McGraw-Hill. All rights reserved.

Formerly Additional General Manager Southern Railway Chennai and Guest Faculty Indian Institute of Technology Madras

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To

My wife Leela

PREAMBLE There are very few books covering the entire gamut of bridge engineering, right from the investigation stage to design, construction and maintenance, specially with the background of practices prevalent in India. Mr Ponnuswamy’s contribution is a welcome one, for students as well as engineers directly engaged in planning, designing, construction and maintenance of bridges. Mr Ponnuswamy writes with knowledge backed by extensive experience in construction and maintenance of bridges on the North-Eastern, Northeast Frontier and South-Central railways. He has also carried out techno-economic feasibility studies and detailed planning for construction of a road bridge across the mighty Brahmputra river near Tezpur in Assam. I am sure this would serve as a valuable reference book and a useful addition to the library of every civil engineer. K BALACHANDRAN

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Member, Engineering, Railway Board and Ex. Officio Secretary Ministry of Railways Government of India

FOREWORD It is a great pleasure for me to write the foreword for Bridge Engineering. As I see it, this book would be of immense value to both students and practising engineers. Bridges are the most expensive structures of railways and highways and the author has rightly retraced the history of bridge building in this country and elsewhere to enable an engineer to make the correct choice of the type to be adopted. As for the other parts, he has brought together all information that an engineer may require for a particular item. As a railwayman and a professional with 34 years of experience in both construction and open line, I would like to congratulate Mr Ponnuswamy for this excellent work.

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B C GANGULY Formerly Chairman, Railway Board and Ex. Officio Principal Secretary Ministry of Railways Government of India

PREFACE TO THE SECOND EDITION In the past twenty years, since the book was first published, the author has received a number of suggestions from different professionals and his colleagues for some corrections and additions in the book. He also received requests from students for additions in the design aspect part. Since 2000, many of the design codes of BIS, IRS, and IRC have undergone many major changes calling for some update in the earlier editions. Some of these required changes have been kindly attended to by the publishers in the tenth reprint and carried forward. With the publishers now agreeing to bring out an enlarged second edition, the author has taken the opportunity to make some major additions in chapters relating to designs covering scour round piers and design of superstructures and foundations. A few examples of combined foundations have been added in Chapter 12. Two new chapters (Chapters 21 and 22)—one on Grade Separators and one on River Training Works, have been added to make the book more comprehensive. Chapter 21 of the previous edition has been renumbered as Chapter 23, and modified by adding a few more abbreviations and a list of books for reference. Chapter 21 deals comprehensively on grade separators. Grade separators many a times become a multiple bridge structure. Their planning requires some knowledge of traffic engineering and geometry. Aesthetics also play a very important role in their planning, as they are in urban areas. Chapter 22 covers an allied subject of river training works, basic knowledge of which is essential for engineers who plan and design crossings across major rivers.

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Author regrets that he has not been able to cover the design aspects of two currently popular topics viz., ‘cable stayed and suspension bridges’ and ‘continuous span girders’ as he did not get an opportunity to study these in depth. Some of the detailed designs requiring reference to standard tables and graphs have been included as appendices at the end of the book. The basic structure of the book has been kept the same as in the first edition. It is hoped that readers will find the book more useful. S. PONNUSWAMY

PREFACE TO THE FIRST EDITION Bridges are defined as structures which provide a passage over a gap without closing the way beneath. These may be needed for the passage of railways, roadways, footpaths and even for carriage of fluids. Bridge engineering is a fascinating subject for any civil engineer and it will not be an exaggeration if one says that any young civil engineer who starts a career either in railway or highway department or starts work with a consultant, looks forward to an opportunity to work on some bridge project. No other creation of a civil engineer has such appeal as a bridge. Bridge construction technology has been growing with the development of human civilisation. Once man found the need to move about, he had to cross obstacles and had to find ways for doing so. Man has developed the idea of bridge construction by observing many instances of natural behaviour. For example, the development of timber bridges can be traced back to the initial use of accidentally fallen trees across a stream. Suspension bridges are nothing but a development of monkey-trains or connecting together creepers hanging from trees for crossing. The arch bridge is a development of the idea obtained from naturally formed rock arches or caves.

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Initially, naturally available materials, such as stone and timber were extensively used for making bridges. At present, we may not be able to find traces of ancient bridges constructed out of timber as it is a perishable material. However, we can find some traces of old structures made up of stone, all over the world, mostly in the form of arches, since stone is fairly indestructible. It is surmised that the earliest construction of permanent bridges started around 4000 B.C. The lake dwellers of Switzerland are said to be the pioneers of timber trestle construction. Indians developed the prototype of the modern suspension bridge at about the same time even though, like in many other fields, other countries have overtaken us now in this field and India has no suspension bridge worth the name, except a few foot bridges such as the one across river Ganga near Rishikesh. The arch bridges were developed simultaneously by the Romans and Chinese. The Chao-Chow bridge built around 600 A.D. is perhaps the longest lasting vehicular bridge today. It is situated 350 km from Beijing and is of single span of 37.4 m, which must have been quite an achievement in those days. The oldest pedestrian bridge still standing, is a stone slab bridge across river Meles in Smyrna, Asia Minor, which according to a Greek legend is at least 2500 years old. Bridge construction received a spurt with the advent of cast iron, and since the early eighteenth century there has been development and innovation in design and adaptation of material. A spectacular development was seen in construction, particularly with the advent of reinforced concrete and pre-stressed concrete. Steel was first, extensively used in the Eads Bridge at St. Louis, Missouri, built in 1874. Use of steel led to the development of cantilever bridges, the world’s most famous one being the Firth of Forth bridge in Scotland with two main spans of 521 m built in 1899. The world’s longest span cantilever bridge was built in 1917 at Quebec over the St. Lawrence River with a main span of 549 m. India can

xiv

Preface to the First Edition

boast of one such long bridge, the Howrah Bridge, over River Hooghly, built during the Second World War with the main span of 457 m which is, the fourth longest span of its kind. There are many steel arch bridges, the longest one being over Kill Van Kull at New York, with a span of 504 m. The longest concrete arch bridge is the Gladesvelle Bridge in Sydney, Australia, with a span of 305 m. Longer and longer spans have been developed with suspension bridges. In 1816, one such suspension bridge was built in Philadelphia with a span of 124 m and today the longest one is Humber Bridge in UK with the main span of 1400 m completed in 1982. Theoretically, it is considered feasible to construct suspension bridges of spans as large as 3000 m.

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In India, the earliest major bridges were built as a part of the railway system. In ground communication, India has built many roads, the maintenance of which was commented upon by the Chinese travellers during the Mauryan period, but there are no available records of any major bridge on highways. The Moghuls were more interested in building famous monuments and architecture developed considerably during that period. In the British period, the need for communication, mainly on administrative and strategic grounds was felt, and the first major development was towards construction of railways which required a large number of bridges. By the time railway construction started in India, cast iron and wrought iron had already been invented and so British engineers made good use of them, particularly for long spans and for bridges in the Indo-Gangetic plain. They also relied on local materials, such as brick and stone, and constructed a large number of arch bridges which are still serving very well in spite of considerable increase in the wheel load passing over the bridges. Most of the iron bridges built by British engineers have been re-built, particularly the superstructure part. Since the early twentieth century, the need for development of roads and Grand Trunk routes was felt and the government turned its attention towards it. By this time, concrete had also come into being as a versatile construction material. Hence, road engineers went in for either arch or reinforced concrete bridges. In the eastern parts of the country, large scale use of timber and steel truss bridges with timber decks overlaid with bituminous concrete wearing coats, had been in vogue. With the advent of pre-stressed concrete, in the early forties the versatile use of this material was well understood by road and railway engineers and they enthusiastically started making use of it. The earliest pre-stressed concrete bridge to be built in India was by the railways near Siliguri on the Assam Rail Link Project. Similarly, the first pre-stressed road bridge to be built in India was the one across river Palar near Madras. In both these cases, one prototype girder each, was tested to destruction at the commencement of construction. Indian road engineers have kept themselves up-to-date in the development of this material. Highway engineers have been using it extensively and have built bridges with spans up to 140 m. Railway engineers in India have not shown the same enthusiasm and the longest prestressed bridge span constructed on railways is 24 m, while in Japan, they have gone in for spans of up to 105 m. The latest entrants in the field of bridge engineering are the steel box girders and cable stayed bridges. The earliest of this type to be built is, the Maraikabo Bridge in Venezuela with a main span of 235 m. The first major bridge of this type is yet to be built in India. But the day by which this method will be used is not far off as the second Hooghly Bridge under construction is adopting this system. Bridge building should involve considerable amount of forethought, conceptualisation, planning and in-depth study, as it is the costliest part of a road or rail project and calls for utmost economy. It takes the longest time for completion. Bridges across rivers and streams are the most vulnerable as any major damage to the structure can completely upset the total communication system. Hence, no undue risk can be taken in their design and construction.

Preface to the First Edition

xv

A study was made by David W. Smith on the failures of 143 bridges constructed between 1847 and 1975. According to him, the majority of bridges failed due to flood and foundation movement, and an analysis made by him is given in Table P.1. Table PP.1 .1 Analysis of Cause of Failure of Bridges in USA Cause of failure

Total number of failures

Flood and foundation movement Unsuitable or defective permanent material Overload or accident Inadequate or unsuitable temporary works or erection procedure Earthquake supplementary cause in one instance Inadequate design in permanent material Wind Fatigue Corrosion

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Total

70

Remarks

22

2 earth slip; 1 floating debris; 66 scour; 1 foundation movement 19 by brittle fracture of plates or anchor bars

14 12

10 ship or barge impact Inadequacy in permanent design

11

5 4 4 1

3 cast iron; 1 hastened by corrosion

143

He also found that there is a cyclic occurrence with regard to the failure of bridges due to defective design. Considering the five such major failures which he had studied, it is seen that the main cause for this has been that with increasing adaptation of a material or type, the engineer tries to economise more and more, and fails to take into account some aspects which are critical and at the same time not known to be so. For example, the failure of Tacoma Narrows Bridge, a suspension bridge of 850 m span, was mainly due to aerodynamic oscillations about which little was known at the time of development of design for the bridge, the deck of which was made too wide and at the same time slender. The study indicates the importance of foundation stability and the need for providing adequate water way to minimise the probability of failure due to floods. It is therefore necessary that an engineer entrusted with a bridge work should have a good knowledge of the various aspects of investigation. Economy in bridge construction as well as its long life can be ensured by the use of proper materials, effective supervision and also through the use of an economic method of construction. Even a study of the economy achieved over a period has shown that the economy due to design is hardly 3 to 4 percent, while the economy of using effective methods of construction and economic use of labour has resulted in greater cost reduction. This emphasises the need of the design engineer get acquainted with to the construction methods and problems involved.

xvi

Preface to the Fist Edition

A bridge can deteriorate or get damaged during service, and as a major bridge is built with an anticipated life of 100 years, the need for proper surveillance, maintenance and use of proper materials cannot be over emphasised. When damages occur, quick methods of reconstruction, or even reconstruction of the existing bridge to meet modern requirements will call for a thorough knowledge of maintenance repairs and rebuilding practices. This book has been planned taking these important aspects into consideration. The design aspects of various components have also been covered as they have a bearing on both the choice of the structure and method of construction. It is difficult to cover such a vast subject in one book and the references given at the end of each chapter would provide more details. Since the book is mainly meant for students and engineers of this subcontinent, the problems peculiar to local conditions are dealt with, while at the same time reference to important structures built outside India have been made to encourage the reader to set his targets high. Both the Indian Railways and the Indian Road Congress (a technical statutory body under the Ministry of Transport) have evolved standards and codes of practice which are of particular relevance to bridge materials, design and construction for railways and roads, respectively. Indian standards issued by the Indian Standards Institution are followed for other details. Considerable material has been borrowed from these publications as also from published books, periodicals and departmental practice. Thus, there is nothing original in the content of this book. The book has been divided into three sections, i.e., Planning and Investigation; Design and Construction and; Maintenance and Rebuilding. There may be, to a certain extent, repetitions of material particularly with reference to geotechnical and hydrological investigations, and such repetitions have been purposely made so that each chapter can be taken as a self contained one and minimum cross referencing is required.

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Part I comprising Chapter 1 to 6 covers “Planning and Investigation.” Chapter 1 covers the historical development of bridges and different aspects of planning and conceptualisation of a bridge structure including aesthetics. Chapter 2, 5 and 6 will give an undergraduate student sufficient basic information, while the other chapters cover more details to meet the requirements of post-graduate students or practicing engineers. Part II, comprising of Chapter 7 to 15, covers “Design and Construction” aspects. Chapter 7 deals with types of bridges and bridge components as loading standards. A study of this chapter should meet the requirement of a fresh student of bridge engineering. Chapter 8, regarding setting out works, is meant for a practicing engineer. Chapter 9 through 12 deal with the various types of foundations which have been explained briefly in Chapter 6. Details of design aspects are covered in these, along with their construction methods so that they can be of use to senior students and practicing engineers. Chapter 13 covers substructures and Chapter 14 and 15 deal with superstructures. In both the cases, design aspects (along with construction problems) are included to the extent to which they are of particular relevance to bridges. They will be of interest to both students as well as practicing engineers. For detailed design methods, further reference to design text books will be necessary. The last part, “Maintenance and Rebuilding” is divided into five chapters. This will be of interest to all students desirous of studying the problems of maintenance, and will be of particular use to practicing engineers. Chapter 16 deals with the need for regular inspection of bridges and the various aspects that have to be looked into, during such inspections. Chapter 17 and 18 cover the problems in the maintenance of the various components of bridges in which the practices prevalent in other countries are also

Preface to the First Edition

xvii

touched upon. Chapter 19 comprises of case studies on rebuilding/reconstruction of bridges and will be of particular use to practicing engineers and will also be of reading interest to students. Chapter 20 briefly covers construction management as applicable to the building of new bridges as well as rebuilding of old ones and include one example of network analysis for each. REFERENCES 1. Shirley, Smith H., World’s Great Bridges, English Language Book Society, London. 2. Victor, D.J., Essentials of Bridge Engineering, Oxford & I.B.H. Publishing Co., New Delhi, Revised Edition. 3. Ozako, Yoshio and Fujio Machida, “Recent Developments in Concrete Bridges in Japan.” The Structural Engineer, Institution of Structural Engineers, London, October, 1978. 4. Smith, David W., “Why do Bridges fail?”, Civil Engineering, American Society of Civil Engineers, November 1977.

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S PONNUSWAMY

ACKNOWLEDGEMENTS The idea of writing this book was first suggested by Shri D. Ajitha Simha. Shri Simha took the trouble of going through the draft of the book and gave many useful suggestions. Shri C. Balasubramanian not only went through the chapters on design but also redrafted some parts. Shri M.N. Prasad went through the entire draft of the first edition, gave useful critical comments and also supplied some additional material for inclusion. (Late) B.C. Ganguli, who was approached by the author for a foreword then, took the trouble of going through the entire draft and gave many useful suggestions, including a modified format for the book. These along with the reviewer's suggestions proved invaluable in giving the final shape to the first edition of the book. . The author has been receiving many suggestions subsequently in these 20 years since the first publication for improving its contents. Prof. N. Rajagopalan and Prof. D.J. Victor pointed out a few errors in the first edition and gave suggestions on additions required. Shri S. Subramanian went through the design examples and corrected them. He also helped the author in drafting the revised introductory chapter. Prof. N. Rajagopalan went through the additions made on box girder design and corrected the same meticulously. Shri R. Balasubramanian went through and corrected the additional chapters as well as the additions made in Chapter 5. Alok Garg, M.I. Ahmed, N.P Sharma and Smt. Shobana helped the author in collecting some technical data for inclusion in this second edition of the book.

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The typescript of the first draft was typed by K.R. Gopalakrishnan and Veeraraghavan. The final draft of that edition was typed by R. Lakshmi Narayanan, K.V. Srinivasan and Sivanandan in a very short period. Smt. V. Srividhya provided secretarial assistance in preparing the additions in this edition to a large extent. The sketches and drawings were prepared by hand during 1980s by A. Sampath, M. Nageshwara Rao, P. Yarakachari, S. Parthasarathy, S. Tharanipathi, John Swamiraj and N. Dhandapan. Some of them were arranged by Shri P.K. Verma. Shri G. Thyagarajan helped the author in liaising with the publishers during the printing of the first edition and also prepared the index for the same. P.D. Hari Krishnan and V. Ramesh gave logistic support during the revision of the book. The author is very grateful to all of them and many others who have helped in many ways in the publication of this book in 1985 and its revision now. The Railway Board readily granted permission to the author to write the book and lend data from their technical publications and reports as well as granted permission to use data collected by the author during his service. K. Balachandran, the then Member, Engineering, Railway board was kind enough to write the preamble for this book. Without their support and encouragement, this effort would not have been possible. The author has added a number of case studies on foundations and river protection works from technical documentations on two bridges on River Brahmaputra prepared by the author for the

xx Acknowledgements

Northeast Frontier Railway. The author is grateful to the General Manager (Construction) for giving the opportunity to be involved in the documentation and also supply some of the drawings. Considerable material has been taken and some tables and figures have been reproduced from the publications of Indian Roads Congress, International Association Bridge and Structural Engineers, Central water Commission, RITES and Indian Concrete Journal with their kind permission and the same is gratefully acknowledged. The author is also thankful to M/s Hindusthan Construction Company Ltd., M/s Gammon India Ltd., M/s AFCONS Ltd., and STUP Consultants for their permission to use some material or their design reports, sketches and photographs for inclusion in the book. Sincere thanks are due to author's two sons Sadayappan and Senthil Nathan, for their help and encouragement. Finally, the author is grateful to the entire team of McGraw-Hill Education (India) Pvt. Ltd. for their help and support.

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S PONNUSWAMY

COPYRIGHT PERMISSIONS

Standard load diagrams, figures and tables for road bridges appearing in Chapter 7 and 14, Figures 2.5, 2.6, and 16.3, and the formats at Annexure 4.2 and 16.2 have been reproduced from relevant IRC Publications with the kind permission of the Indian Roads Congress, New Delhi. Various railway loading diagrams, tables for EUDL appearing in the text of Chapter 7, permissible stress tables appearing in Chapter 14, Annexure 14.2 (a) to (d), 14.3, 15.1 and Appendix C are extracted from the relevant Indian Railways Standards published by the Manager of Publications for Indian Railways with the Railway Board's general approval. Figures 8.1, 8.2 and 8.3, Sections 8.5 and Annexure 10.1 are extracted from the Madras Highways Manual, Vol. II, Part II—Bridges, published by the Department of Highways and Rural Works, Tamil Nadu, with their kind permission. The figures indicating defects in arches appearing in Chapter 17 have been extracted from Railway Bridge Maintenance by Robert Turton with kind permission of M/s. Hutchinson Publishing Group Limited, London. The following figures and tables are reproduced from the Indian Standards noted against each, and to which references are cited for further details. Fig. 2.7 from IS 1893: 2002 Table 7.4 from IS 1893: 2002

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This reproduction has been done with the kind permission of Bureau of Indian Standards, New Delhi. Reference is invited to the respective IS for further details. It is desirable that for more complete details, reference be made only to the latest version of this standard which is available from Bureau of Indian Standards, Manak Bhawan, New Delhi. Figures 5. 1 (b) to (f) have been taken from FHWA Publication No. HEC- 18 on “Evaluating Scour at Piers.” Though there is no copyright mentioned in the document formal permission has been sought from FHWA. Figure 5. 1 (g) forms part of a paper published by the American Society of Civil Engineers and has been included with their permission. Set of Morice and Little graphs included in Appendix C were originally published by the Cement and Concrete Association, London. The said organisation has been succeeded by a new organisation and author’s efforts to get in touch with them have not been fruitful. However, the graphs have been included in a number of other text and reference books and are being widely used by consulting engineers, presumably there being no restriction in copying them for reference purposes.

xxii Copyright Permissions

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A number of photographs of well known bridges have been taken from different web sites and permissions have been sought wherever copyright tag is attached. Source has been indicated against each photograph, with names of individual contributing the photograph wherever available.

CONTENTS

Preamble Foreword Preface to the Second Edition Preface to the First Edition Acknowledgements Copyright Permissions

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1.

Introduction 1.1 Definition 1 1.2 History of Development of Bridges 1 1.3 Classification of Bridges 4 1.4 Planning for a Bridge 5 1.5 Different Stages of Planning 9 1.6 Preliminary/Conceptual Design 11 1.7 Detailed Design 19 1.8 Summary 22 Annexure 1.1 Some Notable Bridge Links in the World 24 Annexure 1.2 Illustrations of Some Notable Bridges 25

vii ix xi xiii xix xxi

1

2. Investigation for Bridges and Culverts 2.1 Investigation for Culverts and Minor Bridges 35 2.2 Topographic Details 40 2.3 Catchment Area Map 46 2.4 Hydrologic Particulars 47 2.5 Geo-Technical Details 47 2.6 Seismology of the Area 54 2.7 Navigational Requirements 54 2.8 Construction Resources 55 2.9 Particulars of Nearest Bridges 56 2.10 Traffic Forecast 56 2.11 Report and Drawings 57 2.12 Summary 59

35

3. Investigations for Important Bridges 3.1 Factors for Choice of Ideal Site 61

61

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Contents

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3.2 3.3 3.4 3.5 3.6

Techno-economic Feasibility (or Preliminary) Study 63 Project Report Stage 67 Drawings to Accompany the Project Report 72 Project Report 73 Summary 73 Annexure 3.1 Details for Model Studies Required for Siting a Bridge Across a Major and Important River 75 4. Design Flood Discharge for Bridges 4.1 Introduction 76 4.2 Contribution Factors 76 4.3 Methods of Determination of Design Flood 77 4.4 Unit Hydrograph Method 88 4.5 Choice of Method 90 4.6 Foundation Design Discharge 90 4.7 Summary 91 Annexure 4.1 Selected Flood Formulae Evolved Around the World 93 Annexure 4.2 Heaviest Rainfall in One Hour at Various Important Rain Gauge Stations in India 100 Annexure 4.3 Values of Rugosity Coefficient n for Open Channels with Other than Coarse Bed Material 102 Annexure 4.4 Case Study—Design Flood by Unit Hydrograph Method 103 5. Linear Waterway of Bridges ` 5.1 General 108 5.2 Scour and Depth of Flow 108 5.3 Afflux 125 5.4 Calculation of Waterway 127 5.5 Summary 131 6. Choice of Foundation for Piers and Abutments 6.1 Types of Bridge Foundations 132 6.2 Cost Ratio 132 6.3 Clearance 133 6.4 Choice of Foundation 134 6.5 Open Foundation 135 6.6 Pile Foundation 137 6.7 Well Foundation 142 6.8 Block Foundations 144 6.9 Summary 144

7. Types of Bridges and Loading Standards 7.1 Classification of Culverts and Bridges 146

76

108

132

146

Contents

7.2 7.3 7.4 7.5 7.6 7.7 7.8

Components of Bridge Structures 154 Need for Loading Standards 156 Loading Requirements 157 Railway Loading Standards 158 Road Bridge Loadings 170 Some Comments 186 Summary 188 Annexure 7.1(A) Equivalent Uniformly Distributed Load (EUDL) for Railway Loadings for BG and MG Main Lines 190 Annexure 7.1(B) EUDL for Broad Gauge (RBG) Standard Loading on Minor Bridges and Culverts with Ballasted Deck 191 Annexure 7.2 Longitudinal Loads (Without Deduction for Dispersion) 192 Annexure 7.3(A) Typical Load Diagram for Heavy Mineral Loading of Indian Railway Standards as per Annexure 11 of Bridge Rules 195 Annexure 7.3(B) Equivalent Uniformly Distributed Loads (EUDL) in kN and t on Each track 197 Annexure 7.3(C) Longitudinal Loads for Heavy Mineral Loading of Indian Railways—Based on Appendix XIII of IRS Bridge Rules 200

8. Setting Out for Piers and Abutments 8.1 8.2 8.3 8.4 8.5 8.6 8.7

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202

General 202 Aim 202 Setting Out for Minor Bridges and Culverts 203 Setting Out Single Span Bridge 203 Setting Out Multispan Bridge 205 Setting Out for Major/Important Bridges 206 Summary 211 Annexure 8.1 Fixing Towers and Base Line Measurement for Brahmaputra Bridge by Survey of India 213

9. Open Foundation 9.1 9.2 9.3 9.4 9.5 9.6 9.7 9.8 9.9 9.10 9.11

xxv

Open or Shallow Foundations 215 Open Excavation in Dry Condition 215 Foundation Below Subsoil Water 217 Baling Out Water 217 Cofferdams for Deeper Foundations 218 Floating Caisson Process 220 Structural Forms 221 Design Consideration—Individual Footing 222 Design Procedure and Example 224 Raft Foundation 234 Summary 234

215

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Contents

10.

Pile Foundations 10.1 10.2 10.3 10.4 10.5 10.6 10.7 10.8 10.9 10.10 10.11 10.12 10.13 10.14 10.15 10.16

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11.

General 236 Spacing of Piles 236 Material for Construction 237 Soil Friction Factors 240 Precast Driven Piles 241 Design of Pile Foundation 243 Load Tests 253 Strength of Group Piles 253 Lateral Resistance of Piles 256 Factor of Safety 257 Construction 258 Driven Piles Versus Cast-in-situ Piles 262 Large Diameter Bored Cast-in-situ Piles 263 Construction of Bored Piles 266 Structural Design of Pile Foundation 270 Summary 278 Annexure 10.1 Timber Commonly Used for Pile Work and their Properties 280 Annexure 10.2 Design of Precast Driven Piles and Cluster for Pier 282 Annexure 10.3 Dynamic Pile Formulae 287 Annexure 10.4 Determination of Lateral Strength of Pile 288 Annexure 10.5 Load Test on Piles 291 Annexure 10.6 Construction of Substructure for Krishna Bridge Design Calculations of Piers P.6 295

Well Foundation 11.1 11.2 11.3 11.4 11.5 11.6 11.7 11.8 11.9 11.10 11.11 11.12 11.13

236

Types of Wells 302 Caissons 305 Design of Wells 305 Sinking Effort 317 Material for Steining 318 Design of Curb and Cutting Edge 318 Construction 323 Sinking of Wells 331 Some Problems of Open Sinking 338 Use of Divers for Sinking 341 Pneumatic Sinking 342 Working of Pneumatic Equipment 345 Rate of Sinking 349

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11.14 11.15 11.16 11.17

12.

Well Foundation—Case Studies 12.1 12.2 12.3 12.4 12.5 12.6 12.7 12.8

13.

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366

Design for a Railway Bridge 366 Construction Problems 369 Formation of Island in Very Deep Channel: Road-Cum-River Bridge Across River Godavari at Rajahmundry 376 Sinking through Rock Using Divers 380 Pneumatic Sinking 380 Case Studies on ‘Tilting’ Corrections 385 Combined Foundations 386 Summary 395

Piers and Abutments 13.1 13.2 13.3 13.4 13.5 13.6 13.7

14.

Bottom Plug 350 Sand Filling 352 Top Plug and Well Cap 352 Summary 353 Annexure 11.1 Design of Well for Road Bridge Over River Brahmaputra Near Tezpur 355 Annexure 11.2 Second Bridge Across Godavari at Rajahmundry Rail-Cum-Road Calculations for Pressure Under Well Foundation 359 Annexure 11.3 Pneumatic Sinking—Requirement for Decompression of Men 365

398

Function 398 Aesthetics 398 Materials of Construction 401 Piers and Abutments 403 Wing Walls 405 Construction Problems 405 Summary 406 Annexure 13.1 Design of a Pier 407

Superstructure—Design Aspects 14.1 14.2 14.3 14.4 14.5 14.6 14.7 14.8

Historical Development 412 Types of Bridges 413 Choice of Materials 414 Design Principles 414 Design Procedure for Bridge Superstructure 434 Composite Construction 446 Box Girders 448 Continuous Girders 455 Annexure 14.1 Efficiencies of Long-span Bridge Structures

412

459

xxviii

Contents

Annexure 14.2(A) Annexure 14.2(B) Annexure 14.2(C) Annexure 14.2(D) Annexure 14.3 Annexure 14.4 Annexure 14.5 Annexure 14.6 Annexure 14.7 Annexure 14.8

15.

Superstructure—Construction 15.1 15.2 15.3 15.4 15.5 15.6 15.7 15.8 15.9

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16.

Basic Permissible Stresses in Structural Steel 460 Basic Permissible Stresses in Structural Steel 461 Basic Permissible Stresses in Structural Steel 462 Allowable Working Stresses Pac in N/mm2 463 Effective Length of Unbraced Compression Chords 464 Values of k in Pigeaud’s Equation 466 Second Godavari Bridge—Stress Sheet for 45 m Span Girder 467 Design of a Plate Girder 25 m Span 471 Design of a Composite Girder for 25 m Span Railway Loading 484 Design of Bridge Bearings 491

500

Dependent Factors 500 Arch and Slab Bridges 500 Steel Girder Bridges 503 Site Erection Methods 508 Suspension Bridges 518 Cable Stayed Bridges 521 Bearings 524 Case Studies 529 Summary 536 Annexure 15.1 Rules for Prestressing Open Web Girder Spans 537 Annexure 15.2 Longest Suspension Bridges 539 Annexure 15.3 Long Cable Stayed Bridges 541

Inspection of Bridges 543 16.1 General 543 16.2 Necessity for Inspection of Bridges 543 16.3 Inspection Procedures in Various Countries 544 16.4 Procedure for Inspection 546 16.5 Aspects of Inspection 547 16.6 Testing of Bridges 554 16.7 Criteria for Assessment of Safe Load Capacity 555 16.8 Aids for Bridge Inspection and Maintenance 556 16.9 Summary 559 Annexure 16.1(A) Format for Inspection Register for Railway Bridges (Major) 560 Annexure 16.1(B) Format for Inspection Register for Railway Bridges (Minor) 563 Annexure 16.2 Road Bridges—Proforma for Inspection Report 564 Annexure 16.3 Assessment of Bridge Condition and Rating of Bridge 568

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Contents

xxix

17.

Maintenance of Bridges— Substructure 17.1 Foundation 570 17.2 Substructure 574 17.3 Repairs to Leaning Masonry 577 17.4 Maintenance of Arch Superstructure 578 17.5 Repairs to the Concrete Structure 580 17.6 Summary 580

570

18.

Maintenance of Superstructure—Girders 18.1 General 582 18.2 Steel 582 18.3 Oiling and Greasing of Bearings 585 18.4 Cracks in Steel Work 585 18.5 Buckling and Bending in Members 585 18.6 Loss of Camber 585 18.7 Repairs to Steel Structures 586 18.8 Concrete Girders 590 18.9 Summary 590 Annexure 18.1 Metallising Specification and Equipment Needed 591

582

19.

Rebuilding of Bridges 19.1 Why Rebuild Bridges 594 19.2 Replacement 595 19.3 Rebuilding of Pier Tops 596 19.4 Replacement of Girders (Regirdering) 599 19.5 Preliminary Work 600 19.6 Modus Operandi of Various Methods 600 19.7 Girder Renewal with Cranes 606 19.8 Renewal of Girders with Gantries 608 19.9 Enveloping Method 609 19.10 Floatation Method 610 19.11 Rebuilding Over Diversion 613 19.12 Construction without Temporary Arrangements 614 19.13 Summary 615

594

20.

Construction Management 20.1 General 617 20.2 Planning Requirements 617 20.3 Stages of Execution 620 20.4 Planning and Control Techniques 625 20.5 Repairs and Rebuilding Bridges 630

617

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Contents

20.6 20.7

632

21.

Grade Separators 21.1 Planning 635 21.2 Layouts for Interchanges 637 21.3 Detailed Scheme Preparation 643 21.4 Design of the Structure 645 21.5 Summary 652 Annexure 21.1 Some Examples of Special Design Grade Separators 653

635

22.

River Training and Protection Works 22.1 Introduction 658 22.2 Protection Works for Bridges with Reduced Waterway 661 22.3 Design of Guide Bund—A Review 662 22.4 Armouring of Side Slopes of Guide Bunds 669 22.5 Apron Production 673 22.6 Summary 678

658

23.

Abbreviations, Notations and Bibliography 23.1 Abbreviations 680 23.2 Notations 681 23.3 Additional References 683

680

Appendix A

Design Flood Estimation by Frequency Method

687

Appendix B

Design Flood by Unit Hydrograph Method—Field Application

691

Appendix C

Calculations for Load Distribution for Concrete Girders

702

Appendix D

Illustration of a Box Girder Design

716

Appendix E

Miscellaneous Data and Tables for Design

730

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Monitoring and Updating 630 Summary 630 Annexure 20.1 Typical Problems Arising during Project Control

737

Chapter 1

INTRODUCTION

1.1 DEFINITION Bridges are defined as structures, which provide a connection or passage over a gap without blocking the opening or passageway beneath. They can be over streams, canals and rivers; creeks and valleys or roads and railways passing beneath. Bridges are now being provided across ocean bodies and for linking a number of islands as in Japan. Some typical such links1 are listed in Annexure 1.1. The bridge crossing carrying a road or railway over another road or railway is called a grade separator or fly over. The bridge structure can be for passage/carriage of persons, cattle, vehicles, water or other material carried across in pipes or conveyors. When they are used for carriage of water, they are called aqueducts. Even a jetty in the ports and harbours can be classified as a bridge. No other creation of a civil engineer has such a general appeal and fascination to the people as a bridge.

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1.2

HISTORY OF DEVELOPMENT OF BRIDGES 2,3

Bridge building is not a new science. With the growth of civilizations, the need for travel has impelled mankind to find ways and means of bridging gaps over deep gorges and perennial streams, for walking across. The simple form could have been by felling trees across gaps and using them for walking across. Thus timber can be considered as the earliest material to be used for bridging. This has been followed by bridges built with stone and then of brick, used by themselves or in combination with timber. Such bridges have been possible only for short spans. These materials appear to have been in vogue for many centuries till iron was developed around the middle of the last millennium. The earliest reference available is of a bridge across Nile built in about 2650 BC though according to Swedish Institute of Construction the oldest bridge built was an 1100-m-long wooden bridge built in England in 3306 BC. The oldest pedestrian bridge still standing is a stone slab bridge across River Meles in Smyrna, Asia Minor (Turkey) said to be 2500 years old. Swiss were the pioneers of timber bridges, specially using trestle form. In known history, the Chinese appear to be the earliest to build stone bridges. Their earliest stone bridges still in existence to be seen are Zhaozhou bridge and Anji Bridge, an open spandrel arch bridge built between 595 and 605 AD (vide Plate 1.1 and Plate 1.2). They are also believed to have built the earliest C.I. chain bridge in approximately 960 AD. Romans are believed to have built bridges and aqueducts for carriage of water

2

Bridge Engineering

before even the start of the first millennium. Queen Nitocrin built a bridge in stone in about 780 BC with piers built with stone and wooden plank decking. Stones were bound together with iron and lead. Romans are also credited to have used timber pile bents for foundation and piers, the first such known being the one across Rhine built in 95 BC. Plate 1.3 shows a typical bridge of the type ‘Pont du Gard’ built by Romans in the First century AD. Similarly, Gordon River Bridge built in 13 B.C. in France was a masonry aqueduct 49 m high, with three rows of superposed arches. Roman dominance over other countries declined in the twelfth century BC. Etruscans are believed to have used vaults for bridge construction as early as 600 BC Europe is considered one of the birthplaces of bridge design and technology. Thus, they must be the earliest to develop bridge building as a technique. The earliest timber bridge built was, probably, Trojan’s Bridge built in AD 104 (destroyed 6 years later). It was made up of 20 numbers 30 m timber arches over stone piers4. The Roman bridge building art spread to Middle East and as far as India. Marco Polo is said to have remarked, ‘Indian cultures adopted their own tools under this influence for bridge building and further developed suspension bridges’. Indians have built suspension bridges with use of ropes for suspension and bamboo and timber planks for decks in the hilly regions from early days. They are also credited to have built cantilever type of bridges laying stone slabs one over the other in a progressive manner to bridge gaps, but have kept no records.

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In medieval times, the church as part of their activities of building cathedrals influenced bridge building also and there was a Jesuit brotherhood devoted to bridge building. All these bridges and buildings had been built with stone, brick masonry and timber using emphirical methods for design. A typical example is the first London Bridge built by Peter of Colechurch in 1176–1209 AD. This was a masonry bridge with 19 pointed masonry arches on piers, none of them with same dimensions. This bridge lasted for about 600 years. Wittengen Bridge built in 1758 in Germany was the longest timber bridge in Europe with a 119 m span. It was during the Renaissance period that a start was made to do bridge construction on a scientific basis. The truss system based on the principle of triangles, which cannot be deformed, was developed. Andrea Pallaido (1508–1580 AD), evolved several truss forms, including the king post type. Verrazino (1615) had written about roads, machines, waterwheels, bridges including masonry arches with use of prestressing rods, as well as suspension bridges and use of iron eye bars for suspension bridges. First metal bridge to be built was Coalbrookdale bridge (designed by Abraham Darby III). (vide Plate 1.4). It was built in cast iron in 1776. James Finlay patented suspension bridge form and built some with steel chains. But they were found to be subject to severe corrosion problems and needed frequent attention. French Engineer Vicat invented the aerial spun cables for suspension. This type has become the major form for building longer and longer span bridges of today. The earlier popular arch form adapted to cast iron and the truss form adapted for different shapes in W.I. and steel, revolutionized bridge building using iron and steel as basic spanning materials instead of masonry and timber respectively. This dominated the scene for many centuries till the arrival of

Introduction

3

prestressed concrete. Eads bridge at St. Louis was the first bridge to be built with extensive use of steel, as early as 1874. (vide Plate 1.5) Firth of Forth Railway Bridge in Scotland followed suit, with use of tubular steel sections for main girders and columns. Though, today, there are critical comments on the over design of the bridge, disaster and doubts about its cost economics in the wake of the Tay Bridge disasters, this appears justified. Forth bridge design had been appreciated for the bold attempt made to span such lengths and shaping the structure so as to follow clearly the force lines and giving an elegant look for a viewer from distance, as can be seen in Plate 1.6. Trend in 18th and nineteenth centuries for longer span bridges especially in USA tended towards cable suspension bridges. One of the most elegant of such structures, the Golden Gate Bridge in the San Francisco bay in USA, built in 1937 is shown in Plate 1.7. It was the longest of the kind at that time. The first Portland cement concrete bridge to be built was the Grand Maitre Aqueduct across River Vane in France built in 1867–74. France is also the birthplace of prestressed concrete, which is the major form of bridge superstructures all over the world today either by itself or in combination with steel.

Present Trend

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Japanese also built iron bridges in the same period as others. They have the longest cable suspension bridge, Akashi Kaikyo Bridge, with a record span of 1991 m as on date. (vide Plate 1.8). Germany was the first to introduce the concept of cantilever construction and incremental launching of concrete decks, as well as the modern form of cable stayed bridges. Russians used timber as main bridge building material up to the end of 15th century, though some of the former republics in USSR had built masonry bridges. One of the old bridges, built in 1234 A.D. still in existence is the Sanainsky Bridge over River Debda-chai in Armenia. China has built some notable bridges using tied arch form and cable stayed bridges. Two elegant examples are, the Dagu bridge at Tianjin (vide Plate 1.10) and a railway bridge at high altitude on their recently opened rail link to Tibet. They have built the longest steel tied arch bridge (as of 2006) Lupu bridge (vide Plate 1.9). Franklin D. Roosevelt once said ‘there can be little doubt that in many ways the story of bridge building is the story of civilization. By it, we can readily measure a progress in each particular country.’ Based on this saying, the Indian civilization being one of the oldest, must have built bridges well before Christian era. Unfortunately, to the best of the author’s knowledge, there is very little readily reachable record on the subject in India, from which one can discern when the earliest bridge was built in India, except for the mythology mentioned in previous section. According to records of Chinese travellers on Indian history, India appears to have had a good highway system in the days of Harshavardhana or even earlier. Such highways must have had a number of bridges. Firoze Shah who ruled in Delhi in midfourteenth century is said to have built canals and bridges along with schools and hospitals. One can still see some old masonry arch bridges built by the Portuguese in 16th or 17th century in Goa. One old bridge still in use is the stone slab bridge across River Cauvery at Srirangapatnam built by Tipu Sultan who ruled in the eighteenth century. We have a number of old masonry and stone arch bridges built in the middle of the nineteenth century on the Railways, which bear testimony to the skill of the local people in bridge construction. The British who built the railways had brought the steel bridge girders and their designs from UK, but they depended on the local skills and expertise to build the others. Sructural forms and designs for longer spans also appear to have come from the British. The technical knowledge within the country has since kept pace with the developments abroad and their application

4

Bridge Engineering

has, however, been governed by the opportunities available within the country. A number of cable stayed bridges has been built in India in the past two decades, the major ones being the Vidhyasagar Sethu across Hooghly at Kolkata and the Naini Bridge on River Jamuna at Allahabad. The railways are building a number of major bridges including a large steel arch bridge in Jammu and Kashmir. The Border Roads Organisation has erected a cable stayed bridge using Bailey Bridge girders in early part of this millennium, which bridge is claimed to be only bridge of the type at highest altitude in the world at the time of construction.

1.3

CLASSIFICATION OF BRIDGES

Bridges are classified severally. The broad classification and sub grouping are indicated below: Table 1.1 Classification of Bridges

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Sl. No.

Main classification

Sub classification

1.

Function

Foot; Road; Railway; Road-cum-rail; Pipe line; Water conveying (aqueduct); Jetty (Port)

2.

Material

Stone; Brick; Stone; Timber; Steel; Concrete; Composite; Aluminium; Fibre

3.

Form

Slab; Beam; Arch; Truss; Suspension; Cable supported)

4.

Type of support

Simply supported; Continuous; Cantilever

5.

Position of floor/ deck

Deck; Through: Semi through

6.

Usage

Temporary; Permanent; Service (Army)

7.

With respect to water level

Causeway; Submersible; High level (normal case)

8.

Grade separators

Road-over; Road under (sub way); Fly over (Road over road)

9.

With respect to connections (Type of jointing)

Pin jointed; riveted/ bolted; Welded

10.

Movable bridges (over navigation channels)

Bascule, (Plate1.14) Lifting, Swing (Plate 1.15)

11.

Temporary bridges

Pontoon, Bailey, Callender-Hamilton, Light alloy portable bridges developed by the Army

Based on the waterway, bridges are classified differently by railway and highway engineers in India. Indian Railways group the bridges with 18 m or over linear