Engineering Nature: Timber Structures 9783955535537, 9783955535520

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TIMBER STRUCTURES



TIMBER STRUCTURES

Engineering ngineering Nature Nature

Contents

004



RESEARCH AND TECHNOLOGY 010 Mannheim Multihalle – The Power of the Temporary 016 Hardwood Load-Bearing Structures 024 Experimental Doubly Curved Gridshell Structures

030 Practical Timber Structure Design – Working with Specialist Firms 036 The ­Integral Stuttgart ­Timber Bridge 042 6 0 Metres: The Tallest Timber-Hybrid High-Rise in Switzerland

ROOFS 052 Archery Hall in Tokyo 060 Chapel in Sayama 066 Stadium in Nice 076 Sports Hall in Rillieux-la-Pape 084 ­Garage and Vehicle Workshop in ­Andelfingen 090 Sports and ­Leisure Pool in Surrey

100 St. Josef P ­ arish Church in ­Holzkirchen 108 Delicatessen W ­ holesale Store in ­Stuttgart 116 Heuried Sports Centre in Zurich 124 The ­Macallan Distillery in ­Aberlour 134 Mactan Airport Terminal 2 142 Hall 10 at M ­ esse Stuttgart

MULTI-STOREY BUILDINGS 152 Residential Tower in Heilbronn 162 Conference Hall in Geneva 172 Theatre near Boulogne-sur-Mer 180 International House in Sydney

190 Timber Office High-Rise in Risch-Rotkreuz 198 Timber High-Rise in B ­ rumunddal 208 Schönbuch Tower near Stuttgart

APPENDIX 218 Authors 220 Image Credits

005



222 Project Participants 224 Imprint

Foreword Jakob Schoof

Forward into the Wood Age

006



Back to the Future – this film title from the 1980s could best describe the renaissance that timber construction is currently experiencing around the globe. Ecological advantages in particular make timber construction full of promise for the future: wood is carbon neutral over its lifecycle. A timber structure becomes temporary storage for a material that can, in the ideal case, be reused after deconstruction or, where this is not possible, thermally recycled. Steel and reinforced concrete, on the other hand, are energy intensive to manufacture; the production of cement alone is currently responsible for around eight per cent of global CO2 emissions. However, the timber renaissance also includes a good chunk of “Back”. Historian Joachim Radkau, who writes widely on the history of technology, describes the era shortly before industrialisation in Germany as the “Wood Age”. The renewable raw material was used, perhaps even overused, for almost everything: all kinds of commonplace objects, machines and in the construction of houses, ships and vehicles. This led to astounding craftsmanship in working with wood and a high level of knowledge about its properties. Similar developments took place in other forested regions of the world. And even in the 20th century, as concrete and steel increasingly displaced wood as a primary building material, engineers were still producing structural masterpieces of timber construction. In 1908, the nine-storey Butler Square warehouse in Minneapolis was completed with a load-bearing frame constructed using Douglas fir timbers up to 60 cm thick. In 1934, Deutsche Reichspost, Germany’s then provider of postal and broadcasting services, built the “Bavarian Eiffel Tower”, a radio transmission mast almost 160 m tall to the east of Munich. Just short of 40 years later, the tower had to be demolished using explosives because of severe deformations. In comparison, today’s tallest wooden towers still have some way to go: the world’s current tallest timber building, Mjøstårnet in north Oslo, measures 85.4 m from its base to the top of its pergola. We discuss this building extensively in this book. However, in deciding the content, we were not led by such a collection of superlatives, but rather by the observation that timber structures are establishing themselves in many more areas of construction, and by the question of which structural and regulatory limits confront timber construction today. In this book we also take a look at the design of timber structures and the technical developments that make contemporary timber construction possible. This includes the use of hardwoods, with their unsurpassed load-bearing capacity, and the increasing number of composite structures in which wood, steel and concrete interact optimally according to their material properties. Because that, too, is part of the truth in the new Wood Age: wood is not the only material making up a timber building. Connecting ­elements, tensioned cables, columns and girders made of steel and solid floor slabs made of concrete are almost always required to make today’s timber structures fit for purpose in terms of spans, sound insulation and fire protection.

007



Research and Technology

008



MANNHEIM MULTIHALLE – THE POWER OF THE TEMPORARY

010

HARDWOOD LOAD-BEARING STRUCTURES

016

EXPERIMENTAL DOUBLY CURVED GRIDSHELL STRUCTURES024

PRACTICAL TIMBER STRUCTURE DESIGN – WORKING WITH SPECIALIST FIRMS

030

THE ­INTEGRAL STUTTGART ­TIMBER BRIDGE

036

60 METRES: THE TALLEST TIMBER-HYBRID HIGH-RISE IN SWITZERLAND

042

009



M  annheim Multihalle The Power of the Temporary

Text Georg Vrachliotis

A

A  roof covered with a ­translucent, PVC-coated polyester fabric

B  National Garden Show in Mannheim 1975, access to the hall from the south

010

ESSAY

C  digitally calculated ­overhead view of the gridshell produced on an automated drawing

machine, only every 3rd lath is shown

“Dear Professor Otto, We read with interest in the press about your polar city under a plastic dome. Because we are currently concerned with similar questions, we would like to meet with you today and discuss our problem.” These were the opening lines in an official ­letter to Frei Otto written by Werner Haas, one of the two managing directors of the National Garden Show in Mannheim. The letter dated 21 June 1971 reached Frei Otto at a time when he was under great pressure working on the construction of the transparent roof landscape for the Munich Olympics site designed by architects Behnisch & Partners. To enter i­nto a discussion with Otto, it would therefore have been quite enough to refer to the prestige project currently under construction – or perhaps, in view of the enormous international publicity, look back to the tent roofs of the German pavilion, which Otto completed with Rolf Gutbrod for Expo 67 in Montreal. Werner Haas instead mentioned the City in the Arctic, a German-Japanese research project carried out by the University of Stuttgart Institute for Lightweight Structures (IL). Together with Kenzo- Tange and the engineers from Ove Arup, Otto investigated whether it was feasible to put a roof over a city of 40,000 people by erecting a gigantic pneumatic dome stabilised with negative pressure. At first sight, the parallel drawn in the letter – that the National Garden Show Mannheim could possibly be struggling with “similar questions” – might ­appear weird and completely megalomaniacal. 1975 PERSPECTIVES: HOMES FOR THE FUTURE Only later in the letter is it clear what was seen as the common thread of the two ­projects: “The National Garden Show Mannheim, which is scheduled for 1975, will focus up to 60 % on urban design. In particular, it looks ahead and seeks to demonstrate at a scale of 1:1 on the exhibition grounds how we might live in the future.” B

C

011

Mannheim Multihalle – the Power of the Temporary

Reflecting on the lightweight themes which the National Garden Show had featured in post-war Germany up until then, it is clear how visionary the organisers’ thinking was at that time. This time, instead of concerning itself with new trends in garden design, it would tackle the fundamental question of “living for the future”. The show was attempting to explore the future using experimental thinking. Carlfried Mutschler + Partner emerged with garden architects Heinz H. Eckebrecht as the winners of the national competition for the d ­ esign of Herzogenried Park, which included the construction of a residential development, an information boulevard and the over-roofing of an almost 160 × 115 m area of parkland: a challenging commission in any respect. SOCIAL MICRO-UTOPIA It was no coincidence that the closely related intellectual resources of Frei Otto were sought. The idea of enclosing exhibitions, residential areas and landscapes in long-span climate skins had featured many times in his work. Thinking in terms of large-scale structures had already appeared in his dissertation “The Suspended Roof”, which was published in 1954. In it Otto describes rope nets and pneumatic structures that he spanned as floating roofs over valleys and landscapes to create an artificially controlled climate with residential developments below. In the context of the National Garden Show Mannheim this meant treating technical and social structures as equivalent in the design. Thus, even today, the ­Multihalle is not only the world’s largest timber gridshell structure but is also a social micro-utopia. COMPLEX SUSPENDED MODEL The special role the empirical experiment played becomes clear when you realise the complexity of manufacturing the filigree 1:100 suspended structure models that Frei Otto developed for the conception, construction and structural design of the gridshell. To visualise the basic idea of a gridshell covered with a translucent fabric, a small concept model was made out of finely meshed fly-screen material and pinned down D

012

ESSAY

E

F

G

D  Atelier Frei Otto in ­Warmbronn, around 1973: model constructed with support frames and net scale 1:100

013

E load tests on the complet­ed gridshell – using refuse bins filled with w ­ ater, January 1975

F Frei Otto on the Multihalle gridshell, 1975

G The Multihalle model hangs upside down on brass supports. The marble base protects the model from uncontrolled changes

in shape due to fluctuating relative ­humidity and temperatures, Atelier Frei Otto, Warmbronn, Dec. 1973

Mannheim Multihalle – the Power of the Temporary

H

I

H Multihalle today: the translucent polyester fabric was replaced in 1982 by a white roof membrane

I  view from the walkway into the exterior and interior spaces of the completed gridshell

014

ESSAY

to a mounting board of balsa wood by trial and error. Despite the unsophisticated nature of these models, the form of the final Multihalle is quite recognisable. Then work started on making the net for the suspension model out of several differently sized smaller nets, with each net being made from specially manufactured wires and rings. What is remarkable is that every element in the model either performs a structural function or is a specific component of the Multihalle. A thin brass wire in the model simulates the structural system lines of the real support beams, a fine chain represents the curves at the edges of the structure and an acrylic glass strip models the top edge of the concrete foundation. The completed suspension model then had to be photographed from above and from two perspectives so that it could be used as the basis for a 3D computer drawing, which was required in particular for logistics and planning the installation. “THE INSTALLATION WAS BREATHTAKING” The Ove Arup engineers had initially assumed the structure would be lifted into place using cranes, but they quickly realised that it would be safer to push the whole gridshell up to the required height using an improvised lifting system of scaffolding towers and forklift trucks. After all the laths had been laid out flat on the ground in a 50 × 50 cm mesh pattern, the arrangement was lifted using the mobile scaffold towers and fastened down at the edges. Once raised in this way to the required height, pre-installed bolts at the node points were tightened to lock the gridshell into its final shape. FLOWING, FASCINATING, UNFATHOMABLE With its flowing lines reaching skyward in all directions, the Multihalle cannot be assigned to any of the familiar architectural epochs, nor does it follow any of the trends in styles that experts refer to in categorising the built environment. It is neither a simple roof nor a solid object, neither an archetypal house nor a permanent building. Considering the process involved in its creation, the Multihalle is first of all not much more than a built snapshot of an equally unusual and innovative design process. It is not only an unfinished chapter in ­architecture’s long search for the power of the temporary. The Multihalle is also one of the most unfathomable and yet fascinating images in the architectural history of experimental thinking in the 20th century.

015

Mannheim Multihalle – the Power of the Temporary

Text Frank Lattke, Anne Niemann, Klaus Richter

Hardwood ­ Load-Bearing Structures B

A

A Knochenhauer Amtshaus, Hildesheim, 1529 longitudinal section, cross section not to scale

B structure in beech LVL, office building in Augsburg, 2015 Architects: Lattke ­Archi­tekten, Augsburg

016

ESSAY

Structural engineer: bauart konstruktions ­GmbH, Munich

C summary of use of wood types according to works Source: Weimar H, ­Jochem D (eds) “Holzverwendung im Bauwesen – Eine Markt­studie im Rahmen der Charta für

Holz” Thünen Report 9, Johann Heinrich von Thünen-­Institut, Hamburg, 2013

Indigenous hardwood is used mainly for interior fittings in today’s construction industry. Historic structures show that this was not a ­ lways the case. For example, some types of hardwood, in particular oak, were used in roof trusses as well as post-and-beam structures because of their durability and high strength (Fig. A). Hardwoods currently play a somewhat marginal role in timber construction. At the moment, engineers working to Eurocode 5 may design with five hardwood types (ash, beech, maple, oak and poplar) and use them as solid wood. AVAILABILITY AND POTENTIAL FOR STRUCTURAL USE IN GERMANY Motivated by environmental protection objectives and climate change, the forestry conversion from uniform coniferous to mixed deciduous stands under way for many years in Germany’s forestry industry has not only led to a continuous increase in hardwood production, but also to a long-term reduction in the proportion of softwood produced. The hardwoods include a wide range of species, types and hybrids, each with their own very specific characteristics relating to engineering and chemical properties, structure, colouration and durability. Comparing the volume of t­imber in German forests (1.4 billion m3 hardwood) and the annual growth (12.36 billion m3 hardwood) with the actual consumption (Fig. C), it is clear on the basis of the quantities of undressed timber that there is nothing to stop a manifold increase in the use of hardwood in construction. Only six tree species presently have any realistic potential for increasing the use of hardwood in load-bearing construction: ash, beech, maple, oak, poplar and birch. Hardwood-specific sorting processes have been developed over recent years for these species, which, together with investigations i­nto strength and sectional dimensions, allow grading into the European strength classes in accordance with EN 338 (Fig. G). These show that beech and ash have the potential to achieve particularly high strengths if visual sorting into strength classes is augmented by mechanical determination of the modulus of elasticity. The high strengths exhibited by hardwood species in the higher density range have yet to be fully exploited. Trials on beech and ash have shown average values of approximately 60 N/mm2, which is more than twice the strength of spruce.

C

in 1000 m3 *

SOFTWOOD Volume %

WOOD TYPES HARDWOOD TROPICAL WOOD Volume % Volume %

External wall (construction) 1253 10.9 40 2.4 Sloping roof 2475 21.6 44 2.6 Flat roof 505 4.4 49 2.9 Facade (cladding) 397 3.5 4 0.2 Thermal insulation 2648 23.1 294 17,4  Internal wall 660 5.8 46 2.7 Ceiling 594 5.2 12 0.7 Floor 866 7.5 707 41.7 Windows 101 0.9 17 1.0 Solar shading 14 0.1 1 0.1 Internal door 299 2.6 133 7.8 External door 60 0.5 29 1.7 Stairs 32 0.3 108 6.4 Formwork 267 2.3 13 0.8 External works 1308 11.4 200 11.8 Total 11 476 100 1696 100 *  Built cubic metre equivalent, i.e. the volume a product occupies in a building in m3

017

0 0 0 3 0 0 0 18 30 0 4 23 1 3 155 237

Hardwood load-bearing structures

0.1 0.0 0.1 1.1 0.0 0.0 0.0 7.8 12.5 0.0 1.8 9.9 0.4 1.1 65.3 100

TOTAL Volume % 1293 2519 553 403 2942 706 605 1591 147 15 436 112 140 283 1662 13 409

9.6 18.8 4.1 3.0 21.9 5.3 4.5 11.9 1.1 0.1 3.3 0.8 1.0 2.1 12.4 100

SPECIAL FEATURES OF TIMBER CONSTRUCTION Hardwoods have a complex microstructure and share the functions “conduction” and “mechanical support” between two cell types, which, together with the storage cells, are arranged longitudinally and transversely in the trunk. The properties of the individual cells (density, grain angle of the microfibres, chemical composition) and their arrangement in the wood tissue determine the most important physical parameters in the longitudinal and transverse directions of the wood (anisotropy). Despite common systemic features (e.g. annual growth rings, wood rays), these property values show great scatter, not only between but also within species. In addition, the chemical properties are more heterogeneous in hardwoods than they are in softwoods. Spiral growth is also encountered in certain species. Carpenters who work with hardwoods have developed various strategies for preventing air from entering the conduction paths in the heartwood. The intensity of the take up of liquids into the heartwood depends on the prevalence of this mechanism. A significant disadvantage in using hardwood is the high and ­uneven swelling and shrinkage of different hardwood species, e.g. beech, in which moisture changes in the wood and its relatively long drying time can lead to high differential strains in the wood microstructure, resulting in reversible dimensional changes and cracking. Because of their high densities, hardwoods such as beech, oak and ash ­generate high swelling strains when they absorb moisture, which must be taken into account when used.

D

F

E

D –F Ash strengthening of spruce GLT in a compos­ ite timber/concrete slab. Regional sports centre Sargans, 2012 Architects: Blue Architects, Zurich; Ruprecht

018

Architekten, Zurich Structural engineer: WaltGalmarini, Zurich

ESSAY

G Classification of structural timber into grading classes and assignment into EN 338 strength classes. The number after C and D is the bending strength in N/mm2.

Source: Schmidt M. et al. “Bauen mit Laubholz”, LFW aktuell 98, pp. 37– 39, 2014 (with ­additions by the authors)

TIMBER ENGINEERING SOLUTIONS The characteristics associated with the microstructure of wood mean that the potential for hardwood in timber construction can be ­exploited only by either sawing the full cross section into parts and using glued products instead of solid wood, or thermally or chemically treating the wood to reduce the amount of moisture taken up. Both courses of action aim to minimise the effects of the often pronounced swelling and shrinking behaviour. Treating the wood is intended to create a chemical change of the cell wall polymers to regulate their interaction with water vapour. Thermal, chemical and physical processes have been developed and implemented in i­ndustry that increase biological resistance, particularly in the case of timber types with low durability (e.g. beech and ash). However, thermally or chemically treated timber has not been used for load-­ bearing members to date because the process also reduces its elastomechanical ­properties. Reducing the thickness of the lamellae, on the other hand, is technically simple to do and one of the benefits of this is quicker and more homogeneous drying. The thinner wood lamellae can be used to manufacture dimensionally stable products in sizes suitable for buildings and can be easily worked to suit construction requirements. Branches, which have a greater influence on the strength of hardwood than on softwood, can be eliminated in the same way. Research has shown that glued laminated timber (GLT) made from hardwood should have lamellae less than 25-mm thick to minimise the later formation of cracks and moisture-related strains. Adhesive technology is key in joining the lamellae together well enough for suitable hardwoods to be used in construction and in hybrid beams with other kinds of wood. In recent years, the lamellae thickness for beech has been r­ educed to that of veneer on cost grounds to produce the industrially manufactured beech laminated veneered lumber (LVL), which is a ­ pproved for use in construction.

G

STRENGTH CLASSES Softwood Hardwood

C18

C22

C24

C27

C30 D30

C35 D35

C40 D40

C45 D45

D50

Bending strength %  

60

80

90

100

116

133

166

E-modulus %   Softwood  Hardwood

75

92

96

100 92

108 100

117 108

117

LS10+

LS13

GRADING CLASS (VISUAL GRADING) Spruce and pine Poplar Maple Beech Oak Ash * 

S7

S10 LS10+

S13 LS13 LS10+ LS10+ LS10+

anticipated possible grading

019

Hardwood load-bearing structures

LS13 *

SPECIFIC USE OF HARDWOOD FOR HIGH LOADS High tensile and compressive strengths make hardwood especially suitable for slender ­linear structural members (e.g. columns and beams), ideally in the form of GLT or LVL, to span large distances or transfer high loads. The high strength and stiffness of this wood-based material allows considerable material savings with no loss of load-bearing capacity. The quadruple sports hall at the Sargans regional sports centre (Figs. D – F) is constructed completely out of timber and has a slender and aesthetically pleasing load-bearing structure. While the rigid frame corners of the hall are constructed in spruce GLT (GL 36h) and prestressed with grouted steel threaded rods, the ceiling structure of the auxiliary rooms at the side was constructed partially in hardwood. In the bathrooms, for example, ash was used to strengthen the spruce glued laminated timber beams of the composite timber /concrete ceiling construction. This arrangement achieved strength class GL 40. CONNECTIONS AND JOINTS The advantage of hardwood over softwood timber products is much better load capacity in friction and positive fit joints, which in turn increases the quality requirements for structural details and fasteners. Heavy-duty fasteners are therefore used, depending on the strength and loadings on the timber construction: glued connections, grouted deformed steel components, dowelled connections and screws.1 Positive fit connections, such as dowels, pins or dovetails, can be manufactured very precisely in hardwood to form these mechanical connections. Hardwood components are also suitable for local strengthening of structural connections of other types of timber – e.g. beam-column joints in GLT, in which the c ­ olumn is made continuous at the joint with hardwood to improve the mechanical properties (transverse compressive strength). The load-bearing structure of the upper two storeys of the House of Natural Resources at ETH Zurich (Figs. H – I) was designed as a prestressed timber frame with ash used to strengthen the joints.2 Moreover, the higher bulk density of hardwood compared to softwood provides high resistance to penetration and twisting.3 In contrast to the traditional use of self-tapping screws with softwood timber species (such as spruce GLT), with hardwood there is no need to predrill nail or screw holes. Long screws should be used with a lubricant. The selection of suitable cutting tools and drills is important because of their short operational life when machining hardwood. MOISTURE PROTECTION In contrast to softwoods, some hardwoods are very sensitive to moisture. Suitable details to ensure wood preservation as described in DIN 68800-2 are essential in design and construction. Load-bearing components must be designed and installed such that they are protected against the effects of the weather and moisture. Beech, which is particularly prone to swelling as it absorbs moisture, is suitable only for weather-protected situations. The use of beech LVL for structural purposes is therefore approved only for use classes 1 and 2. As part of a research project at the Technical University of Munich, a hybrid structure with columns and beams made from beech LVL and prestressed reinforced concrete units was used for a parking garage (Figs. J – L). Unlike conventional construction systems in steel, the superior surface quality of beech enhances the architecture of the building and its ecological and sustainability credentials. To protect the beech construction, it must have a facade that provides adequate protection against rain and free ventilation. The prototype is therefore designed to have a facade of larch lamellae in combination with continuous, projecting timber boards. Experience with timber ­materials based on beech shows that only a small amount of moisture is necessary to produce material changes. It leads to discolouration, swelling and open joints at glued connections, which result in aesthetic defects and structural damage.

020

ESSAY

H

I

J

K

L

I  prestressed beam / column connection in GLT with locally reinforced with ash, ETH House of Natural Resources, 2015

J –L  prototype design for a building system for parking garages in beech LVL, TUM.wood – Wood in Research and Teaching, TU Munich, 2015

H beech panels as formwork and reinforcement for a composite timber / concrete slab, ETH House of Natural Resources, 2015

Architects: mml Archi­ tekten, Zurich Structural engineer: ­Institut für Baustatik und Konstruktion, ETH Zurich

021

Hardwood load-bearing structures

AN OFFICE BUILDING CONSTRUCTED COMPLETELY IN HARDWOOD Beech LVL was used universally for the structure, facade and interior fitting out of the new euregon AG office building, a three-storey timber frame structure (Fig. M – P). Timber protection and preservation were part of the construction concept from the beginning to ensure the quality of the exposed surface of the load-bearing structure and the post-and-beam facade, including throughout the construction phase. 40-mm thick beech LVL boards are fixed and sealed in place immediately after ­installation over the exposed timber beam ceiling (support spacing 5.10 m) with main and secondary beams at 85 cm. The columns and beams were coated by the manufacturer during fabrication with a water-soluble intermediate glaze based on pure acrylate. In spite of this, it was not ­possible to completely prevent the ingress of water, which led to discolouration in the ceiling in some places. The dark stains on the surface of the beech boards were sub­ sequently bleached with oxalic acid to achieve the desired appearance of the delicately proportioned structure. CONCLUSION The technical properties and the high aesthetic potential of hardwood are responsible for the material’s increasing use in architecture. Hardwood is a readily available material offering many and diverse options for the future – in the form of slender components or structural elements for highly loaded structures – and will surely continue to surprise us with further innovations.

M

M–P  Use of beech LVL in the load-bearing ­structure, facade and fitting out. Office building in Augsburg, 2015 Architects: Lattke ­Architekten, Augsburg

022

Structural engineer: bauart Konstruktions GmbH, Munich

ESSAY

N

O

P

Literature: 1 E. Gehri, “Verbindungs­ techniken für auf ­Laub­hölzer basierte ­Holzwerkstoffe – mit besonderer Berücksichtigung von BSB

und LVL aus Buche”, in: ­Internationales ­Holzbau-Forum 2015 – Volume 2, GarmischPartenkirchen, 2015.

023

Hardwood load-bearing structures

2 Prof. Dr. A. Frangi, ­“Decken- und Rahmensysteme aus Laubholz – ETH House of Natural ­Resources”, in: ­Interna­tionales ­

Holzbau-Forum (IHF 2014) – Volume 2, Garmisch-­ Partenkirchen, 2014.

3 M. Enders-Comberg und M. Frese, “Buchenfurnierschichtholz – Leistungsmerkmale, Anwendung und ­Entwicklungs-­

 öglichkeiten”, m in: Karlsruher Tage 2014 – Holzbau, ­Karlsruhe 2014.

Text Eike Schling, Rainer Barthel

Experimental ­ Doubly

A

Curved G ­ ridshell Structures A  lattice structure based on asymptotic curves and built out of flat beech veneer strips exclusively orthogonal to one another

B  Mannheim Multihalle Architect: Frei Otto

024

ESSAY

It is easy to design free-form building envelopes on the computer. Curved structures ­also offer the advantage of an efficient, spatial load transfer, like a shell. However, in building such structures, a higher degree of complexity must be taken into consideration during planning, design, fabrication, construction and in their logistics. The authors have been studying the geometry and construction of curved ­surfaces as part of the research project “Repetitive Grid Structures” at the Technical University of Munich (TUM). This project does not aim to cover all digitally designed surfaces and their seemingly unlimited diversity. The focus rather lies on certain ­geometric structures that can be built from simple elements with a reduced number of parameters. The study shows that these repetitive structures follow fundamental principles of form that offer new possibilities for design and construction. B

CONTINUOUSLY CURVED LOAD-BEARING STRUCTURES The starting point for the research described here was the timber gridshells of Frei Otto (Fig. B). These gridshells use the elasticity of their components to create a ­continuously curved lattice structure from straight wooden laths. The question arises: what is the relationship between curvature and construction of the strained structure? The following article analyses the geometric ­properties of curves on doubly curved surfaces to derive new potentials for the ­fabrication and design of strained, load-bearing structures with continuous elements. CURVATURE The simplest way to explain the term “curvature” is by considering a single curve in space: the curvature at any point is determined from the tangential circle of curvature at that point (Fig. C). The curvature equals the inverse of the radius (k = 1/r). The curvature of a surface is determined at each point individually. This is done by creating the intersection curves through this point based on perpendicular planes. The two intersection curves with the maximum and minimum curvature are orthogonal to one another and determine the two principal curvatures k1 and k2. The Gaussian curvature (K = k1 × k2) and the mean curvature H = (k1 + k2) / 2 can be calculated from these principal curvatures. If the radii of curvature of the two principal curvatures lie on opposite sides of the surface, it gives rise to a negative Gaussian curvature. Such a surface is called anticlastic, e.g. like a horse’s saddle. If the two radii lie on the same side, then the surface has a positive or ­synclastic curvature, e.g. like a football. If one of the principal curvatures is zero, the surface is said to be singly curved. Surfaces with constant single curvature are developable.1 This means they can be unrolled in one plane without distortion or change of length, like a piece of paper. Looking at a curve on a surface, every point can be referenced by a coordinate system consisting of a normal vector (z), tangent v­ ector (x) and tangent normal vector (y). If this coordinate system (also known as the “Darboux Frame”) is moved along the curve, the rotations of the curve can be measured about all three coordinate axes. The three a ­ ssociated forms of curvature are called: geodesic curvature (about z), geodesic torsion (about x) and normal curvature (about y). 025

Experimental doubly curved Gridshell structures

C

E

curvature of a curve

curvature of a surface

curvature of a curve on a surface e

z

y

z

r

r1 x

x r2

curvature k = 1/r

Darboux Frame

rotation around ... x = geodesic torsion y = normal curvature z = geodesic curvature

Gaussian curvature K = k1 × k2 Mean curvature H = (k1 + k2)/2

F

Curvature of a surface G

D

z

z

x

x

y

y

curved lines on a planar surface

geodesic curves

z

z

x

x

y

y

rulings of a hyperbolic paraboloid

principal curvature lines

z

z

x

x

y

y

great circles on a sphere

asymptotic curves on anticlastic surfaces

C overview of the curvature of curves, surfaces and curves on surfaces

D overview of curve networks that select (left) or avoid (right) a particular type of curvature

026

ESSAY

E Planar network with purely geodesic curvature. The profiles remain perpendicular and bend only laterally. This forms a plane grillage.

F Gridshell with two families of straight lines. The timber laths twist only about their own axis.

G Two line family network of strips along the great circles of a sphere. The components are tangential to the surface and can be developed as straights.

H

I

J

In the lecture theatre, these three curvatures are often explained using the following scenario: imagine driving a car through a landscape of rolling hills: where the road goes up and down, the driver experiences normal curvature. If the road turns right or left, the driver experiences geodesic curvature. If the road banks to the side, the car tilts due to geodesic torsion.2 The lines of the timber gridshells designed by Frei Otto have all three types of curvature. The timber laths have to be bent and twisted in all directions. The doubly symmetrical profiles must be appropriately flexible in bending and torsion, otherwise the laths cannot be bent into the required position. CURVED NETWORKS ON SURFACES How do these different curvatures effect the path of a curve and its network? If only one or two of the described forms of curvature are permitted (and the others avoided), then a classification for curve networks can be created (Fig. D) that permits a direct conclusion to be drawn about how a shape can be modelled from developable surface strips. To verify this behaviour, physical models were built, using thin strips that only bend about their weak axis. Networks with just one type of curvature are scarce: A network of curves displaying only geodesic curvature exists merely on a planar surface (Fig. E). Pure geodesic torsion can be found on a hyperbolic paraboloid (Fig. F) and normal curvature alone, occurs within the great circles of a sphere (Fig. G). There are specific types of curves, which avoid one of the three curvatures: geodesic curves, for example, display no geodesic curvature, and thus follow the shortest path between two points on a surface (Fig. H). Principal curvature lines, on the other hand, have no geodesic torsion. A respective network will consist of two families of curves that will always intersect at 90 degrees (Fig. I). Curves that have no normal curvature are known as asymptotic curves (Fig. I). They exist only on anticlastic surfaces. In a similar way to principal curvature lines, asymptotic curves follow a direction field, so that the designer can choose only a start point but not the path of the curve. If the surface is locally planar, the quadrilateral network forms a singularity with six or even eight sides. Asymptotic curves have great advantages for construction: they can be formed from straight strips perpendicular to the surface, which can transmit local loads along their strong axis. In the case of zero mean curvature, i.e. minimal surfaces, asymptotic curves are perpendicular to one another. All node points are then identical and right-angled. In this case, the only parameter needed for fabrication is the distance between nodes.

J The structure of this sixpoint sail runs along the asymptotic curves. The model was assembled out of planar, straight plastic strips with vertical slits.

H Gridshell based on two directions of geodesic curves. The components can be unrolled but are partly twisted.

I Lattice structure along the principal curvature lines, which can be built with profiles standing upright or on their sides. In both cases, the components are developable.

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EXPERIMENTAL DOUBLY CURVED GRIDSHELL STRUCTURES

ASYMPTOTIC DESIGN In summer 2016, a preliminary design for a research pavilion was developed as part of a post-graduate architectural study. Student Denis Hitrec used a single minimal surface, known as Schwarz D, which is defined by six edges of a cube (Fig. L). A continuous interwoven minimal surface is created by point mirroring and addition of the cubic module. From this a rectangular section was selected, upon which the network of asymptotic curves is generated. This gridshell can be described using only five different line segments (Fig. L). The 1:5 scale wooden model demonstrates the advantages for construction (Fig. A, M): the asymptotic grid was assembled out of flat, straight strips with exclusively orthogonal nodes. ASYMPTOTIC GRIDSHELLS Since 2017, asymptotic curves have been investigated systematically with great development for their construction and applications. In the summer of the same year, the first large-scale prototypes were created in wood and steel, which allowed the construction of a 12 x 6 m gridshell at the TUM main campus in the autumn (Fig. K).3 The first commercial structure, an entrance portal for the Intergroup Hotel in Ingolstadt, was completed in winter 2019. Architects and engineers at the TUM and the University of Hong Kong are currently working on applications for kinetic gridshell structures and doubly curved facade elements. THE WAY AHEAD This strategy represents only one of the many possible ways in which the construction of complex forms is significantly simplified by consciously choosing a more suitable surface and structure. Often slight adjustments suffice to convert an architect’s freeform shape into a geometrically practicable building system. Following this strategy, we hope that free-form design can leave the niche of extravagant architecture and reveal its full potential in terms of efficiency and economy.

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K construction of a steel gridshell at the TUM main campus (2017)

L, M The minimal surface of the Asymptotic Pavilion is assembled from beech veneer strips and can be defined by six edges of a cube.

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EXPERIMENTAL DOUBLY CURVED GRIDSHELL STRUCTURES

Literature: 1 H. Pottmann, A. Asperl, M. Hofer, A. Kilian, “Architectural Geometry”, Bentley Institute Press, Exton 2007.

2 C. Tang, M. Kilian, H. Pottmann, P. Bo, J. Wallner, “Analysis and Design of Curved Support Structures”, in: S. Adriaenssens et al. (ed.),

“Advances in Architectural Geometry”, vdf Hochschulverlag at ETH Zurich, 2016.

3 E. Schling, „Repetitive Structures“, Dissertation, TUM, 2018.

Text Wolfgang Müll

Practical Timber Structure Design – Working with Specialist Firms 030

ESSAY

The enormous diversity of wood-based materials and connections, the manifold aspects of building physics, continually changing standards and recognised rules of technology and not least the interaction of all these points can make designing timber buildings very time-consuming and costly. One way to deal with this complexity and yet be sure of designing structures that are practical and within budget is to involve specialist firms at an early stage. Combining skills to develop details together can be to the benefit of all project stakeholders. This essay discusses a few projects in which this approach has led to success. HAGER FORUM IN OBERNAI For the Hager Forum in the French town of Obernai, timber construction company Holzbau Amann provided early advice to the architects Sauerbruch Hutton and structural engineers Werner Sobek (Fig.A–E). The original design was a 39 m × 156 m timber grillage with a grid module of 3 m × 3 m, which was to be supported on only a small number of steel columns. A timber roof with long edge cantilevers was envisaged to allow the roof loads to be transferred into the area of the concrete stairwells. The timber cross sections deepened towards the columns to clearly express the flow of forces. The plans showed individual elements being bolted together. The 3-m wide and up to 12-m long elements were manufactured out of two glued laminated timber beams with a glued-on, cross-laminated timber panel. The shear forces and moments occurring in the transition between roof and columns were to be transmitted by concealed steel plates and continuously threaded bolts (Fig. B). Having decided on prefabrication, the architects foresaw the decisions to be made about the methods of manufacture, connection techniques and installation A

B

tolerances and persuaded the client to involve us as the contractor (Holzbau Amann) to provide advice at an early stage. One of our tasks was to complete the structural ­engineering design of the erection phase and ensure the structure complied with the architectural requirements. We identified several aspects that made construction more costly and complicated when considered from the point of view of glued timber elements and looked for alternatives. Our first thought was a rafter-purlin alternative, but the shallowness of the beam required by the architect would have led to very high deflections because of the lack of grillage ­action. Instead, we developed a d ­ irectional hybrid structure with steel main beams clad in glued laminated timber running trans­versely to the structure and timber secondary beams running longitudinally (Fig. C, D). The connections of the partially haunched ­timber beams at the steel beams were stiff in bending so that the continuous beam effect in the longitudinal direction and the structural action of the grillage were maintained. The top layer of cross-laminated timber boards was connected by nails at close centres to the secondary beams to ensure distribution of the vertical load. These measures made it possible to achieve the A, B Hager Forum in Obernai

structural engineering design (Werner Sobek Frankfurt):

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Practical timber structure design – working with specialist firms

possible ­prefabricated elements near the ­column joints

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C–E Hager Forum in Obernai

C  isometric steel roof members (blue) with purlins

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D workshop drawing 1 timber-frame element preassembled in factory 2 purlin-steel roof member standard connection

3 purlin standard ­connection

E interior

originally planned depth of beam. In order to take into account the loads due to climatic influences acting on the horizontal timber boards, cross-cut timber veneer, a measuring device for relative humidity and temperature and a system to monitor the moisture content of the wood were installed. We worked in a mutually open and trusting r­ elationship with Werner Sobek to develop this final alternative, which was adopted. The advice from a specialist timber engineering firm paid off for the client: everything was very well prepared ahead of construction on site and the limited budget for time and cost was not exceeded. Our alternative was EUR 250,000 cheaper than the original solution. HERMÈS SHOP IN THE GUM STORE IN MOSCOW We received an enquiry for the manufacture of a feature timber staircase at the end of 2014. The idea had been developed jointly by RDAI Architectes and consulting engineers Bollinger+Grohmann and consisted of 145 vertical, curved timbers with a cross section of 40 mm × 60 mm, which together create a free-form surface (Fig. F–I). The structure of the feature staircase was made available to us in the form of a Rhino model along with the questions of practical feasibility and cost. We had already developed curved timber sections working with the same multidisciplinary team for the “Hermès Rive Gauche” in Paris and therefore we were familiar with the expectations of the architect in terms of the finished quality. The particularly difficult challenge presented by these stair balustrades was that they were manufactured out of doubly curved sections which twisted at the same time. Any incongruities in the model were eliminated in the detailed design working in conjunction with Bollinger+Grohmann and “Design-to-Production”. For example, eliminating any radii that were too tight or sharp kinks. The architectural design envisaged that the ­individual verticals in the balustrade would stand up adjacent to one another without any form of connection. To position the sections such that the desired even gap pattern would be achieved, we suggested placing spacers between them. After this idea had been rejected by the architect, we F

G

H

I Color/Principal radius of curvature 52 cm < Rp < 70 cm 70 cm < Rp < 1.10 cm 110 cm < Rp < 1.60 cm 160 cm < Rp

F – I Hermès Shop in the GUM department store in Moscow

H sample sections

I construction design (­Bollinger+Grohmann), overview of different timber bending radii

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Practical timber structure design – working with specialist firms

developed what was the finally approved proposal to use the handrail and the top closure as spacers. The handrail was created out of doubly curved timber sections, while the top balustrade closure consisted of a singly curved flat steel profile. We made sample sections to confirm feasibility before the final order was placed (Fig. H). ECKERT LOGISTICS HALL IN WALDHUT-TIENGEN Single-storey industrial buildings with steel roofs are usually cheaper than similar ones with timber roofs. The main reason for this is the smaller structural depth of the steel beams, the resulting lower overall building height and the frequently adopted two-pin frames with simple moment-stiff corners and low foun­dation costs. However, when fire protection requirements apply, the price advantage is ­reversed. According to industrial building construction regulations, load-bearing structures can be designed to have R30 fire resistance with fire compartments up to 3,000 m2, without the need to fit a fire detection system. Compared to steelwork, which requires an i­nsulating coating, the R30 requirement imposes no significant additional costs on timber structures. On the other hand, with no requirement for fire resistance (R0) and no fire detection system, the permissible size of fire compartments is restricted to 1,800 m2. We were requested directly by the client to prepare an alternative to a steel roof construction which had been planned for a logistics hall (Fig. J–L). The development plan for the area called for a minimum roof slope of 8°. The 37.5-m span between columns and the roof angle made it suitable for a timber truss solution. We decided on a system height of 3.5 m. To keep the system height to a minimum, we designed singlespan purlins – which meant a continuity factor could not be used in the design of the trusses. The connections were formed with multiple-shear slotted steel plates and thin

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dowels. Based on our ­input, the client commissioned the timber variant, which not only offered cost advantages but also created a pleasant room atmosphere. The new, high-strength timber-based construction material Baubuche, a laminated veneer lumber made from beech, allows timber trusses to have still shallower system heights. We are currently designing a production hall roof with a span of 40 m and an overall truss height of 3 m. WORKING TOGETHER TO ACHIEVE THE OBJECTIVE Close cooperative working between the a ­ rchitect, structural engineer and specialist firms, possibly in small networks, can pay ­dividends for all project stakeholders if they work together in a non-partisan manner and are open to new ideas. The feedback circle with the contractors allows architects and e ­ ngineers to see how their designs may be optimally realised. This applies particularly to details, which can both fulfil the design ­ideals of the architect and provide practical and cost-secure solutions. Contractors should, of course, never forget to conclude an agreement for payment with the client for the advice they provide before they provide it.

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Practical timber structure design – working with specialist firms

Text Thorsten Helbig

The ­Integral A

Stuttgart T­ imber Bridge A  Weinstadt-Birkelspitze Bridge was opened for the Remstal Garden Show in May 2019. It has a clear span of 32.20 m.

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The “Stuttgart Timber Bridge” is a new type of bridge with a long service life over which it should require the least possible amount of maintenance. It was developed by the engineering consultancy knippershelbig in cooperation with architects Cheret Bozic, timber ­construction experts from the Materials Testing Institute (MPA) at the University of Stuttgart and the timber construction company Schaffitzel. The concept for the research and development project funded by the cluster ­initiative Forst und Holz Baden-Württemberg was awarded the German Timber Construction Prize in 2017. The first three Stuttgart ­Timber Bridges entered use at the opening of the Remstal Garden Show in May 2019. LEARNING FROM HISTORICAL TIMBER BRIDGES For centuries, timber was the preferred material for constructing bridges. The alternative, masonry, was much more difficult to work. Wood, a locally available resource, was easily and cost-effectively processed by neighbourhood carpenters for building bridges with small to medium spans. Timber bridges built in the 17th and 18th centuries and continuously maintained are still in use today. These bridges are almost all roofed or fully enclosed timber trusses or arch structures, such as the old bridge over the Rhine at Bad Säckingen, the oldest and longest covered timber bridge in Europe. With the beginning of industrialisation in the 19th century, steel followed by reinforced and prestressed concrete in the 20th century became increasingly used instead of wood as a bridge-building material. Despite the rapid acceleration of technological development in the last 20 years, for example in the fields of adhesive and threaded fastenings technologies and in industrially manufactured large-format timber-based construction elements, timber has continued to lose its earlier important role in bridge construction. Frequent serious defects discovered in the often inadequately designed and built structures of the 1970s and 80s strengthened this trend and confirmed the opinion of many clients that timber bridges were not durable and were e ­ xpensive to maintain. So, for example, in Baden-Württemberg only 62 out of a total of approximately 9200 existing bridges were constructed with timber as the load-bearing material (data from 2012). A research project, which commenced in 2013, analysed the causes of defects in eleven old but still oper­ating timber bridges in the Stuttgart region. The results of the MPA Stuttgart report clearly identified the reasons for the defects, some of which were serious and extensive. These reasons included continuous moist conditions in the bearing area and beneath failed waterproofing systems. Connections exposed to the weather and unable to dry out adequately after becoming saturated with moisture considerably shortened the service life of the bridges. Based on these findings, the new Stuttgart Timber Bridge is a covered bridge in the sense that its timber structural members are sheltered by a cleverly detailed deck. The dense surfacing material projects beyond and protects the glued laminated timber (GLT) beam from the direct effects of the weather. Furthermore, the tops of the solid timber segments are waterproofed with a vapour-permeable film waterproofing membrane. A 15-cm gap between the beam and the walking surface material allows adequate ventilation. FIRST INTEGRAL BRIDGE WITH A TIMBER SUPER­STRUCTURE In contrast to historical timber bridges, the new bridge type is of integral construction, i.e. a bridge with no bearings or movement joints: the beams and abutments are monolithically connected to one another. Glued-in threaded rods, which are connected by the appropriate lap lengths to the reinforcement in the abutments, transfer the bending tension and normal section forces between the timber superstructure and the reinforced concrete substructure (Figs. F, H). The direct coupling of the solid, block-glued GLT deck and the reinforced concrete substructure carries with it the risk of crack formation because swelling and shrinkage of the timber due to changes in its moisture content are constrained. This form of structural connection had not been used before in bridge construction. Therefore, MPA Stuttgart developed and evaluated an extensive test programme and undertook long-term testing of a prototype to validate the connection concept. Load tests on GLT /reinforced concrete test pieces, which were connected with 16-mm diameter reinforcement bars by gluing with two-component epoxy resin, confirmed the calculated load capacity and a very high residual strength. A master’s degree project in 2014 supervised by 037

The ­Integral Stuttgart ­Timber Bridge

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B  bending moment diagram of a single-span beam with built-in supports at both ends under a ­uniformly distributed load  (top) / beam shape ­optimised to follow the

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bending moment diagram (bottom) C the walkway surface protects the beam from the direct effects of weather

ESSAY

D bridge beam cross section scale 1:50 1 140 × 80 × 5 mm RHS steel beam

2 textile-reinforced ­concrete precast slab with 2 % crossfall about the centreline 3 5 –10 mm neoprene ­bearing 4 vapour-permeable film­

waterproofing ­membrane 5 13 × 20 cm thick block-glued GLT 4 ­segments 7 6 2× Ø 90 mm larch GLT handrails bolted

onto U ­ -shaped steel sections 7 ­double posts in S355 2 steel flats, t = 10 mm 8 40 mm stainless steel mesh parapet netting

knippershelbig at the Stuttgart University of Applied Sciences analysed the theoretical and practical issues to be considered for the first adaptation of the “integral bridge” principle involving timber as the load-bearing material. Superstructure, substructure and foundation soils interact with one another; soils and structure must be precisely assessed and the crucial construction components identified. A prototype with a span of 40 m was used for this purpose. The bridge was based on a single, prefabricated timber segment and investigated using varying parameters. The findings showed that timber had favourable characteristics as a material for use in integral bridges. The coefficient of thermal expansion of timber is relatively small, the ratio of strength to Young’s modulus is good and timber’s tendency to creep reduces long-term imposed stresses. THREE PROTOTYPES IN REMSTAL After the design for the project began in 2017 and a restricted tender was awarded in 2018, the first three pedestrian and cycleway bridges – Weinstadt Häckermühle, Weinstadt Birkelspitze and Urbach – of the new, integrated Stuttgart Timber Bridge type were completed in May 2019, precisely in time for the start of the Remstal Garden Show organised by a group of local district councils. The clear spans measure 13.60 m and 32.20 m. One of the two bridges with the larger span, Weinstadt-Birkelspitze, provides a good example and crosses a river to connect the residential area of Trappeler to the north of Rems with Birkel-Areal in Weinstadt-Endersbach. The geometry of its elevation is designed to ensure that the timber superstructure is always above the water surface, even when the river is at its maximum flood level. The form of the superstructure follows the bending moment diagram of the bridge beam under a uniformly distributed load: the cross section reduces from the point near where the timber connects with the concrete abutment to a minimum at the zero moment point and increases again towards mid-span (Fig. B). The steps in the cross section follow from the method of fabrication: a total of thirteen GLT segments each 0.2 m thick in strength classes GL 28c and GL 24h were formed to varying curvatures on the gluing bed and blockglued together in the side-on position horizontally to create the 2.6-m wide and 0.93-m deep bridge beam with a total volume of 45 m3. Hence there are moisture-susceptible cut f­ibre ends only on the top, which is protected against standing moisture by transverse and longitudinal falls and a vapour-­ permeable waterproofing membrane. Other than a blocking coating for the end grain faces in contact with the reinforced concrete abutment, no wood-preserving treatment is required. To ensure that timber delivers the desired durability, MPA Stuttgart monitors the superstructure at eight selected positions using permanent moisture and ­temperature sensors. The data is read and evaluated at regular intervals. It would show whether there was a persistent i­ncrease in the moisture content at the critical areas near the contact joint between the t­imber superstructure and the concrete abutment and beneath the waterproofing film membrane. Fungal attack and other damage can occur above an equilibrium moisture c ­ ontent of 20 %. CARBON CONCRETE AND LEAD WOOL Seventy-eight 20-mm diameter ribbed reinforcement bars between 2.3 – 3.0 m long were embedded up to 1.2 m deep and glued into the 30-m long block-glued beam (Fig. H). M ­ achining the top of the timber created symmetrical cross-falls about the ­longitudinal axis of the deck. After installing the vapour-permeable film waterproofing membrane and the handrail attachment blocks, the prefabricated superstructure was transported to site and ­lifted into position using a mobile crane. Concreting the integral joint areas completed the structural connection of the deck to the ­reinforced concrete abutments. The walkway surface, which is subject to high mechanical loads, consists of prefabricated carbon-­reinforced, fine-aggregate E  manufacture of a test specimen of glued ­laminated timber and ­reinforced concrete

F elevations of bridge beam and abutment

039

The ­Integral Stuttgart ­Timber Bridge

scale 1:50 1 78 × 20 mm grade B500B steel reinforcement bars

2 13 × 20 cm thick block-glued GLT ­segments classes GL 28c, GL 24h 3 Ø 8 mm, l = 260/280 mm full-thread bolts inclined at 45° to

the grain direction 4 t = 15 mm thick bearing angle section, t = 10 mm stiffener, S355 J2 steel 5 Ø 8 mm, l = 640 ­full-thread bolts used

as transverse tension reinforcement 6 location and restraint dowels 7 reinforced concrete ­abutment

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G manufacture of the bridge beam: 13 curved GLT segments, each of which is 20 cm thick, are block-glued together in the side-on, horizontal position

H  8 ribbed reinforcement 7 bars are embedded and glued up to 1.2 m deep into the beam

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I  the prefabricated superstructure was transported to site and lifted into position using a mobile crane

concrete slabs. ­Because the carbon fibre non-crimp fabric is not affected by corrosion, it requires only 10 mm of concrete cover. If this were steel r­ einforcement, then the protective concrete layer would need to be four or five times as thick. Not only is the volume of concrete less but the quantity of cement and therefore the energy used in its manufacture are also reduced by more than 50 %. This new material promises very high levels of durability. To e ­ nsure the walkway surface is not slippy even when wet, the tops of the 3 m × 3 m × 7 cm thick slabs are grit-blasted, which removes with the need for an additional anti-slip and crack-bridging coating. The joints between the slabs are sealed with lead wool. This ­traditional technique, which was used for the reconstruction of the Frauenkirche Church in Dresden, makes the surface durable, low-maintenance and capable of accommodating movement. SUSTAINABLE, UNIQUE BRIDGE TYPE The integral “Stuttgart Timber Bridge” confirms the sustainability of wood, the oldest bridge-building material, and underlines the new possibilities it offers. The monolithic structure without joints or bearings is low maintenance and, because of the high degree of prefabrication, is quick to erect. Climate-damaging carbon dioxide is permanently bound up in the solid, block-glued GLT superstructure. The lower processing stage of this material means that fewer emissions and energy are involved in its manufacture, sale and distribution compared with other bridge-building materials. The unique architectural language of this bridge type arises from its monolithic construction and the cross-sectional shape, which is designed to facilitate its method of manufacture.

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The ­Integral Stuttgart ­Timber Bridge

Text Pirmin Jung

60 Metres: The Tallest H ­ ybrid ­Timber High-Rise in Switzerland 042

ESSAY

Lot 1 is the eye-catcher of the new Suurstoffi development in Rotkreuz, Switzerland, where several timber or hybrid timber residential and office buildings have already taken shape. As the new Suurstoffi campus for Lucerne University of Applied Sciences and Arts, the site accommodates 1,300 students. It has 42,000 m2 of floor space in three buildings connected by a two-level underground car park. The fully glazed 60-m high tower is the focal point of the ensemble. It connects at its base to the adjacent, 25-m high lecture hall building. A detached, 30-m high building of hybrid construction will be added in a second phase. With a short lead time of only 13 months for planning and construction (including excavation of the 8,000 m2 building pit) scheduled to last just 27 months, the ­client consulted with the overall ­planner and decided to design and execute the ­project using BIM and Lean Management. Besides making the planning process more transparent, the aim was to reduce errors and to ultimately provide the b ­ uilding data for a model-­ based facility management system. REQUIREMENTS FOR THE LOAD-BEARING STRUCTURE For their competition entry, the architects had already opted for a sustainable design with a maximum amount of visible timber. In Switzerland, load-bearing wood in high-rise buildings must be encapsulated with plasterboard for reasons of fire safety, which is both costly and aesthetically ­undesirable. But ­linear components can remain exposed if a sprinkler system is installed. The beams of timber framing are considered linear ­components if spaced at least 1.00 m apart. Since visible load-bearing wood floors were not feasible, hybrid timber-­concrete composite (TCC) units with visible wood beams were chosen. For design ­reasons, the a ­ rchitects wanted the cross sections of the visible wood columns to be as uniform as ­possible despite greatly varying loads. Another challenge for the structural design was to precisely determine the ­tolerances and deformation behaviour of the wood columns in relation to those of the concrete core – the difference amounts to several centimetres for a 60-m high building – and to provide a suitable means of adjustment. COMPOSITE ELEMENTS The high-rise building’s floor plans measure 20.4 × 41.4 m. The central concrete core accommodates the stairwells, lifts and building service shafts and stiffens the building horizontally. The solid wood columns along the exterior wall, spaced at intervals of 4.05 m, are joined by flush edge beams. The original plan was to span the 6.65-m deep spatial layer between core and facade with glulam timber beams topped by precast concrete slabs that are grouted in place. The quotations from the concrete firms exceeded the cost calculation by 100 %, however, and even variants with filigree slabs were 58 % higher. Apparently, concrete companies are not yet adequately familiar with hybrid systems, so they price the work disproportionately high. Erne’s alternative proposal to prefabricate reinforced concrete slabs and timber beams as composite units was ­ultimately implemented because it offered the client added value in several respects. The units consist of wood ribs 2× 100/320 mm with a shear-transmitting, 160-mm thick concrete t­opping. Building services (ventilation, cooling, light, sprinkler) run between the ribs; impact sound insulation and cement screed are laid over the ­concrete topping from the ground floor to the 3rd floor, while the upper levels have raised floors. The construction offers the desired noise reduction values and summertime thermal insulation. The TCC units, including the 160-mm concrete topping, are ­prefabricated in a factory by the timber contractor in widths of 2.70 m – with an edge rib on both sides and a double rib in the middle. For the initially specified scheme, we would have linearly resolved the transfer of loads from the floors into the core via the concrete topping. But construction ­tolerances made that impossible with the alternative proposal. Whereas construction tolerances of +/- 5 mm can be assumed for timber s­ tructures – and for the composite units – the t­olerances for concrete work are +/- 30 mm in all directions. The loads now had to be transferred to the lift core via the individual wood ribs. The connection detail was thoroughly redesigned until it fulfilled the architectural, structural and fire protection requirements and logistically resolved the interface between trades. 043

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A The concrete core of the campus’s high-rise ­building was cast with a lead time of three weeks. The timber ­structure and the f­acade followed with a time lag.

B foor plan scale 1:750 section scale 1:1,500 1 core of reinforced concrete 2 column grid 405 cm,

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ESSAY

glue-laminated spruce 3 timber-concrete ­composite (TCC) slabs 270 × 665 cm beams of beech ­laminated veneer lumber

For design reasons and because the construction was progressing so rapidly, the parts connecting the timber structure could not be bolted to the concrete core; they had to rest on a bearing or be welded. As the timber engineers, we added the necessary anchor plates to the IFC-BIM model, and then the structural engineer for the concrete work incorporated them in their formwork and reinforcement drawings. This worked well in the virtual world, but work on site revealed that the geometric position could not always be maintained. Although a surveyor marked out the measurements from the ground slab of the second basement and checked them before concreting began, the core nevertheless deviated beyond the tolerance in some places, making it necessary to adapt the timber structure or laboriously relocate individual anchor plates shortly before assembly. The timber contractor welded angles onto base plates cast into the concrete walls and the corners of the concrete slabs of the TCC units bear on these angles. The shear forces from the wood ribs are transmitted via threaded bolts into the concrete topping, which has three short IPE 100 sections per unit as punching shear reinforcement: one perpendicular to the lift, above the central pair of ribs, and two more at angles of 45° to the corner supports. The base plates, the support angles, and the end plates of the TCC units are protected by encapsulation that ensures fire resistance for 60 minutes. Regrettably, utility lines now conceal this beautiful detail. At the outer walls, the projecting concrete slabs of the composite units bear on solid wood beams whose bottoms are flush with the bottom surface of the units’ ribs. To form shear connections, these beams have notched recesses that were grouted solidly together with the block-outs in the concrete topping above them. Since each composite unit is 270-cm wide, the joints between them lie asymmetrically within the column grid of 405 cm, but always centred above a notched recess. The block-outs for the c ­ olumns alternate from a position in the middle of one unit to the corner of the next. The butt joints and the notched connections were filled with grout after the composite units had been seen in place. To empirically study the structural behaviour of the notched connection in this area, a full-size specimen was tested at ETH Zurich. The results confirmed the structural calculations. BEECH COLUMNS – CLAD WITH SPRUCE The architects sought a uniform structure of beams and columns whose dimensions and cross sections were to be as slim and identical as possible on all floors. This contradicts the fact that the loads on the upper floors are far lower than on the ground floor, for example, where the axial load (Nd) on the typical columns = 2,730 kN, while Nd for the most heavily loaded columns (aligned with the core walls and at the cantilevered parts of the building) = 3,660 kN. To ensure the robustness of the structural system, the ground-floor columns were dimensioned to w ­ ithstand an extreme impact of 180 kN at a height of 1.2 m. For the beams, too, it was a challenge to create a wide variety of required structural cross s­ ections without allowing the outer dimensions to deviate greatly. For example, penetrations for pipes were needed in the beams near the technical shafts. Ordinarily, the wood would be reinforced with bonded steel rods. For the heavily loaded columns and beams, however, we opted for a simpler and more economical solution. We increased performance with better wood properties; that is, by using a firmer hardwood: beech laminated veneer lumber (LVL). On the ground floor, for instance, the lightly loaded spruce glulam columns of strength class GL 32h (permissible characteristic bending stress: 32 N/mm2 as per DIN 1052 from Dec. 2008) have the same 360/400 mm cross section as do the h ­ eavily loaded beech LVL columns of strength class GL 70 (permissible characteristic bending stress: 70 N/mm2). From a design standpoint, the variation of wood species should not d ­ isturb the u ­ niformity of the structure, so the beech LVL was covered with 20–30 mm thick edge veneers that make it indistinguishable from the majority of columns and beams made of spruce: the 40-mm wide veneer layers are visible on the sides, while the front and back have homogeneous surfaces. 045

60 Metres: The Tallest ­Hybrid ­Timber High-Rise in Switzerland

C

F

1

2

D

E

3

C The entire project was planned using BIM and Lean Management ­techniques. For hybrid buildings, this helps ­coordinate timber and concrete construction.

D The concrete topping of the TCC units is heavily reinforced where it rests on the wood beams along the facade.

046

ESSAY

E Columns and beams subjected to especially heavy loading are made of beech laminated veneer lumber. Spruce edge veneers conceal the ­different wood species.

F The dissimilar contraction of the concrete core and the wood columns can be individually compensated by means of height adjustment at the column base.

1 Placement of the TCC unit on the beam 2 Height adjustment and attachment of column

3 bolting down the column, filling with grout

VARYING DEFORMATION BEHAVIOUR Wood and concrete have different behaviours over the long term, meaning they deform differently. In particular, the characteristics of creep – continuous deformation under loading – and elastic deformation also vary between wood and concrete. The main structural challenge was therefore to assess the ­column shortening – in relation to the expected shortening of the concrete core. To complicate matters, the timber and concrete structures were not started at the same time. And the higher the building, the greater the deviations; they amount to several centimetres over a height of 60 m. The wood columns had to be variously elongated so that once all the elastic deformation and creep or shrinkage has taken place, the composite units wind up horizontal. This elongation varied from floor to floor: at the ground floor, the shortening due to loads from the upper storeys was decisive. For the upper levels, the attachment point was below the horizontal because the floors beneath had already deformed. We had to develop a detail for the column base that could be adjusted to the correct height for each storey. In addition, no wood could be subjected to lateral loads at the floor tran­ sition because that would have led to large deformations. This strain-free transition is formed by the p ­ rojecting concrete slab of the TCC unit between the head of one column and the base of another above. The deformation is ascertained by monitoring.

G

stark belastet stark belastet belastet heavilystark loaded

mittel belastet

schwach belastet

Unterzug AW

mittel mittel loaded belastet belastet moderately

schwach schwach belastet belastet lightly loaded

Unterzug Unterzug AW AW beam at ext. wall

Unterzug Kern Unterzug Kern beam Unterzug at core Kern

12th to 14th floor

GL 28 N/mm2 280/320 mm

GL 24 N/mm2 280/320 mm

GL 24 N/mm2 280/320 mm

GL 28 N/mm2 320/280 mm

GL 75 N/mm2 280/320 mm

9th to 11th floor

GL 32 N/mm2 340/340 mm

GL 28 N/mm2 340/340 mm

GL 24 N/mm2 340/340 mm

GL 28 N/mm2 340/280 mm

GL 75 N/mm2 280/320 mm

6th to 8th floor

GL 70 N/mm2 320/320 mm (360/380 mm)

GL 28 N/mm2 360/380 mm

GL 24 N/mm2 360/380 mm

GL 28 N/mm2 380/280 mm

GL 75 N/mm2 280/320 mm

4th to 5th floor

GL 70 N/mm2 320/320 mm (360/380 mm)

GL 32 N/mm2 360/380 mm

GL 28 N/mm2 360/380 mm

GL 28 N/mm2 380/280 mm

GL 75 N/mm2 280/320 mm

Ground floor to 3rd floor

GL 70 N/mm2 320/340 mm (360/400 mm)

GL 70 N/mm2 320/340 mm (360/400 mm)

GL 32 N/mm2 360/400 mm

GL 28 N/mm2 400/280 mm

GL 75 N/mm2 320/320 mm

Glue-laminated spruce

Beech laminated veneer lumber

Spruce edge veneer 20 or 30 mm

G columns and beam cross sections for the various floors

047

60 Metres: The Tallest ­Hybrid ­Timber High-Rise in Switzerland

H

I

J

K

H Edge beam with notched recesses for shear-­ resistant grouted bond to the TCC units and threaded bolts for height adjustment of the columns

I Composite element with penetrations for shear-­ resistant grouting to the edge beams. Safety barrier and attachments for building services are pre-installed.

048

ESSAY

J After installation, n ­ othing can be seen of the complex connection to the lift core or the butt joints between the units.

L

K The block-out in the ­concrete of the TCC unit is grouted to form a shear-resistant bond with the notched recess in the edge beam.

L Notched recess in the edge beam. Each composite element has two notched connections centred on the joints to the adjoining elements.

WEATHER PROTECTION AND ASSEMBLY Concepts for using paint or a movable roof were considered for protecting the wood from the weather and a strategy of sealing the top level combined with component ­protection was ultimately decided upon: the grouting of the TCC units meant the uppermost level was watertight at the end of each workday. Water was drained via downpipes in the core. A film was applied to the wood as moisture protection and the columns were given added physical protection. Thanks to good weather in the summer of 2018, the timber contractor had optimal working conditions. The ability to proceed simultaneously with the timber structure and the concrete core – two trades designed and executed by two different sets of planners and contractors – had top priority for us as timber construction engineers. The general contractor was to work with a three-­storey lead, casting the concrete core while the timber structure was assembled – completing one storey per week. Despite the safety concepts we developed with SUVA (Swiss National Accident Insurance Fund), timber assembly beneath the climbing formwork proved to be too risky when objects fell down during concreting. Nevertheless, the need to alternate the trades led to a delay of only three weeks because the timber contractor was able to erect three storeys in two weeks.

M

1

3

2

4

M section scale 1:20 1 punching shear ­reinforcement IPE 100 2 threaded rod as shear force connection

049

3 reinforced concrete slab 160 mm 4 glue-laminated spruce 320 mm

60 Metres: The Tallest ­Hybrid ­Timber High-Rise in Switzerland

Roofs

050

ESSAY

ARCHERY HALL IN TOKYO

052

CHAPEL IN SAYAMA

060

STADIUM IN NICE

066

SPORTS HALL IN RILLIEUX-LA-PAPE

076

WORKSHOP IN ANDELFINGEN

084

SPORTS AND LEISURE POOL IN SURREY

090

ST. JOSEF PARISH CHURCH IN HOLZKIRCHEN

100

WHOLESALE STORE IN STUTTGART

108

HEURIED SPORTS CENTRE IN ZURICH

116

THE MACALLAN DISTILLERY IN ABERLOUR

124

MACTAN AIRPORT TERMINAL 2

134

HALL 10 AT MESSE STUTTGART

142

051

60 METRES: THE TALLEST HYBRID TIMBER HIGH-RISE IN SWITZERLAND

Architects FT Architects, Fukushima (JP)

Structural engineers Shuji Tada, Tokio (JP)

ఃॉᅡ‫ؙ‬2×36×120

156 36 30 30 36 24

Archery Hall in Tokyo

60

਽অ५‫ؙ‬4-M6‫ق‬L=165‫ك‬ ਽অ५‫ؙ‬

24

103

180

র঎ঝॺ‫ؙ‬2-M10

103

30 6

25 25

র঎ঝॺ‫ؙ‬2-M10 2-M10

60

ਗ෢ പഝ‫ؙ‬tٙ15‫ؙ‬ອ୑ പഝ‫ؙ‬ মৰ৯් ਽౫৳૧࿗ಎ ჽ໿‫ؙ‬18×45 @607ங২ ්ဒଆ਷३‫ॺش‬ ଡୗ৷়ഝ‫ؙ‬t=12

a-a‫ؙ‬൰ં௕

60

052

450

0

12

঍‫ش‬ঝॲक़থঃॖউ 15KN

਽অ५‫ؙ‬2-M6 ਽অ५‫ؙ‬

1365

ฮ‫ؙ‬24×50

60

12

র঎ঝॺ

2-M10

b-b‫ؙ‬൰ં௕ ਽অ५‫ؙ‬2-M6 25 40

15

3648 36 48 18 ༠৖

18

Lٙ6382.1 6382.1 a

ฮ‫ؙ‬12×50 b

਽অ५‫ؙ‬2-M6 ਽অ५‫ؙ‬ 2-M6

15 20 15

6030 60 30

36 36 36 36 12 156

St 2L-50×50×4

਽অ५‫ؙ‬2-M6

෣‫ؙ‬120×120 60

25 50

਽অ५‫ؙ‬4-M6‫ق‬L=165‫ك‬ ਽অ५‫ؙ‬

c

25 25

ᐈ‫ؙ‬120×180

ฮ‫ؙ‬50×24

20 36 ෢ લᑥ঎‫ؙॻش‬tٙ12.5 ‫ۅںڶ‬ ৣ৉‫ؙ‬਽ກੌ ਽অ५‫ؙ‬2-M6 ਽অ५‫ؙ‬

053

606.7

d

12

36

84 c-c‫ؙ‬൰ં௕

bb

aa

a

1 b

sections  scale 1:400 1 archery hall 2 gravel surface 3 target area

054

Archery Hall

3 b

a

site plan  scale 1:2,000

2

The Kogakuin Technical University, situated in the west of Tokyo, commissioned the construction of an archery facility for its campus. A filigree space frame with bars made of Japanese cypress wood spans the column-free space measuring 7.20 × 10.80 m. The 60 × 60 × 60 cm spatial grid leads to slender dimensions for the bars of the structure. The rafters consist of two beams each measuring 120 × 36 mm. Between them, vertical bundles are placed with four wood bars each measuring 36 × 36 mm. They feature grooves that serve to brace six layered horizontal 24 × 50 mm bars. This leads to a cross section resembling a stable triangular frame. The frames were set on top of the ring beams via steel angles and connected with 12 × 50 mm wood bars. They lead through all nodes of the horizontal and vertical bars of the triangular frame and are connected to the nodes with bolts. The roofing consists of galvanised sheet metal. The walls of the wood frame construction are clad in cedar with dark glazing on the exterior and gypsum board on the interior. Despite the strong presence of the roof construction, it emphasises the openness of the space thanks to its filigree character.  Florian Köhler

055

Tokyo (JP)

1

2

6871,5

3

4

5

1365

1365

7280

306030

਽অ५‫ؙ‬4-M6‫ق‬L=165‫ك‬ 103 103

36 30 30 36 24 156

਽অ५‫ؙ‬2-M6 ५ঌ‫ش‬१‫ؙش‬12×50×120

র঎ঝॺ‫ؙ‬2-M10 b-b‫ؙ‬൰ં௕ ਽অ५‫ؙ‬2-M6 25 40

15

3648 18

ఃॉᅡ‫ؙ‬2×36×120‫ؙ‬Lٙ6382.1

St‫ؙ‬2L-50×50×4

60 0 12

a-a‫ؙ‬൰ં௕ 60

450 ਗ෢ പഝ‫ؙ‬tٙ15‫ؙ‬ອ୑ মৰ৯් ਽౫৳૧࿗ಎ ჽ໿‫ؙ‬18×45‫@ؙ‬607ங২ ්ဒଆ਷३‫ॺش‬ ଡୗ৷়ഝ‫ؙ‬t=12

਽অ५‫ؙ‬2-M6

1365

3 50/24 mm lateral bar, ­cypress 4 50/36/6 mm groove 5 wood screw M6

056

Archery Hall

section scale 1:100 details scale 1:20

ฮ‫ؙ‬24×50

ฮ‫ؙ‬50×24 c ਽অ५‫ؙ‬2-M6

෣‫ؙ‬120×120 60 60 120

25 50

਽অ५‫ؙ‬4-M6‫ق‬L=165‫ك‬

60

঍‫ش‬ঝॲक़থঃॖউ 15KN

਽অ५‫ؙ‬2-M6

ᐈ‫ؙ‬120×180 24

਽অ५‫ؙ‬4-M6‫ق‬L=165‫ك‬

b

15 20 15

25 25

306030

180

র঎ঝॺ‫ؙ‬2-M10

axonometric illustration 1 50/12 mm longitudinal bar, cypress 2 36/36 mm bar, cypress

36 3636 36 12 156 ฮ‫ؙ‬12×50

a র঎ঝॺ‫ؙ‬2-M10

103 103

18

25 25

156 36 30 30 36 24

༠৖

36 ෢ લᑥ঎‫ؙॻش‬tٙ12.5 ‫ۅںڶ‬ ৣ৉‫ؙ‬਽ກੌ ਽অ५‫ؙ‬2-M6

606.7

d

12

36

84 c-c‫ؙ‬൰ં௕

057

Tokyo (JP)

058

Archery Hall

059

Tokyo (JP)

Architects Hiroshi Nakamura & NAP, Tokio

Structural engineers Arup, Tokio

Chapel in Sayama 1

060

6

3

5

4

2

7

061

The Sayama Lakeside Cemetery Park, a green space with a cemetery, is located in the centre of the hilly landscape of Sayama in the Tokyo area. On the occasion of the 40th anniversary of its existence, the decision was made to build a new chapel and community hall. The new chapel is located directly along the border ­between the cemetery and a neighbouring forest. It is open to all visitors regardless of their religious denomination. The design aim was to develop a building that offers both a calm and ­intimate atmosphere, but is also harmoniously integrated into its surroundings and dense clusters of trees. In order to protect the trees and their branches, the exterior facade of the chapel is folded i­nward. This leads to the formation of a typical Japanese roof type called Gassho (合掌 “praying hands”).  Sophie Karst

3

3

4

2

1

floor plan scale 1:400 1 chapel entrance 2 altar 3 tombs 4 entrance to columba­ rium, lower level

062

Chapel

063

Sayama (JP)

Text Sophie Karst

1

6

3

5

4

2

vertical section, base scale 1:10

1 4 mm cast aluminium panel 1 mm sealant 0.3 mm stainless steel panel 2 mm sealant 2-ply 12 mm plywood panel 50/30 mm rafters

064

Chapel

section scale 1:100

8

7

50 mm EPS thermal ­insulation 5 mm plywood 2-ply 2 280/60 mm rafters Japanese larch, ­protective finish 3 Ø 32 mm connector steel bolts

4 steel ring screed 200 mm reinforced concrete 5 anti-rotation stopper Ø 22 mm steel tube 6 Ø 16 mm steel bolt,

length 240 mm 7 30 mm natural stone 30 mm mortar bed 40 mm slag concrete integrated underfloor ­heating 80 mm hollow core slab

integrated ventilation ducts 200 mm reinforced concrete 8 15 mm glass facade, glass door float glass

CONTEMPORARY GASSHO CONSTRUCTION The structure consists of steeply arranged ­rafters, so-called Sasu, that are joined by a load-bearing connection along their tips. In order to prevent buckling, they are manufactured from an ­extremely stable type of larch plywood. The edges of the 60-mm deep wood rafters feature chamfering with a radius of 9 mm. Due to the fact that the ridge beam as well as all required metal connectors remain invisible, the structure

seems as if wood posts simply rise from the ground. The glazed triangular openings that are formed by the rafter groups permit views towards the green exterior. Each of the altogether 251 wood rafters differ in length and direction and were cut according to a CNC-controlled 3D model. Despite a maximum length of 9 m, finished beams deviated by no more than 3 mm from the specified dimensions during construction.

ASSEMBLY The freestanding rafters support each other and are connected by a metal plate and dowels along their tips. This results in rafter

pairs with two holes at their lower ends that can be easily connected and secured by bolts.

ROOF CONSTRUCTION The roofing material was supposed to be a ­durable, bendable material that adapts to the curvature of the roof and a regionally sourced material that also displays the surface texture of tree sap. The architects therefore selected

065

Sayama (JP)

cast aluminium panels in six different sizes that are purposely not anodised in order to preserve the irregular texture that results from burn marks during manufacturing.

Architects  Wilmotte & Associés, F–Paris (FR)

Structural engineers Egis Bâtiments Méditerranée, F–Nizza (FR)

Stadium in Nice

066

067

Completed as a public-private partnership (PPP) project in Nice, southern France, the multipurpose Allianz Riviera stadium is used mainly as a venue for football matches. The stadium, which can accommodate 35,624 spectators on three tiers of seats, is used principally by OGC Nice football club, although, in 2016, several international matches of the European Football Championship 2016 took place here. The size of the stadium and its facilities also make it suitable for rugby, open-air concerts and other major events. The stadium is about five kilometres west of the city centre in the new urban development district of Écovallée Plaine du Var, a showcase project for sustainable living and working, one of the many aims of which is to be carbon-neutral in the long term. Not least because of the location, ecological aspects played an important role in the ­architectural competition held by the city a ­ uthorities in 2009, which made it a condition of entry that the teams taking part must include a contractor alongside the architectural and engineering consultants. The award went to contractor Vinci Concessions, who tendered with architects Wilmotte & Associés and engineers Egis Bâtiments Méditerranée. From the beginning, the design had always envisaged a reinforced concrete base below a hybrid, mesh-like steel-timber structure supporting the building envelope and roof. The challenge in realising this structure, which references the surrounding hilly countryside in its undulating form, lay firstly in the generation of a parametric 3D model that could be used without difficulty by all p ­ roject partners to plan and optimise the structure. At the same time, the structure had to consist of standard components of as few different types as possible, despite its high complexity.

068

Stadium

The reason for the use of timber as a construction material, in particular to accommodate the high compressive forces in members on the inside face of the 60 curving half-frames, lay in its ecological advantages. For example, the use of timber reduces the CO2 emissions associated with the structure by about 3,000 t. With a good compressive strength-to-weight ratio, wood also keeps down the total weight of the structure. The favourable modulus of elasticity of wood and the relatively “yielding” construction also led to a roof structure with the required earthquake resistance for this l­ocation. Above the diagonally crossed glued lami­nated timber sections is a tubular steel construction of pyramidal elements, which, together with the members on the outside face, likewise of tubular steel, forms a space frame. The roof surface largely consists of white PVC film to provide shade for the spec­ tators in summer and an 8,500 m2 annular zone with photovoltaic panels. The innermost ring of the roof surface above the pitch and the vertical areas of the external skin are clad with a translucent ETFE membrane – which provides better light for the pitch and concourse. The membrane also allows the structural frame – especially at night when the lights are switched on inside the stadium – to become a defining feature of the external appearance. According to the competition rules, the stadium had to be constructed as an Energy Plus building. To achieve this, the stadium has photovoltaic panels on the roof to exploit s­ olar energy and uses geothermal sources to provide heated or cooled air to the rooms beneath the stands. The stadium has since been awarded the HQE (Haute Qualité Environnementale) certificate – a sustainability ­certificate comparable with the DGNB quality seal – as well as several architectural and timber construction prizes.  Roland Pawlitschko

Membrane

1

Membrane Steel extrados Membrane Steel extrados Membrane Membrane Timber intrados Steel extrados

2

Timber intrados Steel extrados Steel extrados Timber Stands intrados

Stands Timber intrados Timber intrados Stands

3

Stands Base Stands Base

4

Base

Base Base

5

overview of the ­construction layers 1 building envelope as a thin membrane 2 outside face members in steel 3 inside face members in timber

4 spectator stands 5 base structure in ­reinforced concrete

069

nice (FR)

aa 5

5 7

7

7

6

7

6 5 5 6

7

6

5

7

4

6

5

level 3

a

2

2

2

3

3

2

1

3

3 1

level 1 section, floor plans scale 1:2,000

1 VIP area 2 business lounge 3 office 4 press area 5 concourse 6 kiosk 7 technical equipment

070

Stadium

1

1

a

071

nice (FR)

Text Adrien Escoffier

A

B

C 4000 kN 3500 kN 3000 kN 2500 kN 2000 kN 1500 kN 1000 kN 500 kN 0.0 kN -1000 kN -1500 kN -2000 kN

D 572.5 kN 494.0 kN 415.5 kN 336.9 kN 258.4 kN 179.9 kN 101.4 kN 22.87 kN -55.65 kN -134.2 kN -212.7 kN -291.2 kN -369.7 kN -448.2 kN -526.8 kN -605.3 kN -683.8 kN -762.3 kN -840.8 kN -919.3 kN

072

STADIUM

Egis was involved in the structural design of the roof and the elaboration of the geometrical strategy from competition to detailed ­design. The timeline of the design and build project had a great impact on how the development of the geometry concept was set up. The rules of the competition stated that the ­integrated team of architects, engineers and contractors had to

commit to a budget before the competition was awarded. The initial ­design and analysis for the competition took place in two steps: first a presentation of the architectural concept and validation of the structural behaviour, then a detailed analysis of the geometry aiming to prove to the contractors the feasibility of the structure.

FIRST STEP: STRUCTURAL BEHAVIOUR AND MATERIALS The stadium roof is a continuous surface ­enveloping all the spectator seating, starting at ground level then going up as a facade before cantilevering over the seating. The structure is a 3D truss constructed in steel and timber. Timber is used for the members on the inside of the truss, where it is most visible and structurally ­efficient (it is mainly in compression ­under typical loads, see Figs. C, D). At that stage, while the architects were deciding on the shape they wanted to give the roof, we defined a parametrical model that would allow us to generate the

structural pattern over the entire surface. The resulting model, which was used for ­renderings and to produce a 3D print of the physical model, made a positive impression on the whole team, and at the same time raised a lot of concerns about the geometric complexity and non-repetition of elements. In the second step, at the end of which the project had to be priced and presented to the jury, we created a new parametrical definition that would generate the whole structure based on a precisely defined geometry.

SECOND STEP: GEOMETRICAL OPTIMISATION We had to regenerate the shape based on ­geometric rules that would allow repetition in the fabrication of the elements of the structure, especially the steel nodes connecting the timber elements to the steel diagonals. The shape was no longer a freeform non-uniform ­rational basis spline (NURBS) but had turned

A  representation of the three different rotation surfaces on which the whole shape of the ­timber structure is based

B  geometry of the timber structure after the ­optimisation phase; same colours indicate an identical structure

073

nice (FR)

C  typical section showing axial forces in the members

into a 3D arrangement of planes and cylindrical surfaces, which were created by the repetition of a section curve along inclined circular arcs (Figs. A, B). The use of circular arcs to create ­rotational surfaces allowed repetition of the steel nodes, while fitting well with the desired shape being curved both in plan and elevation.

D axial forces in the timber mesh structure

E L)

ue (H

oltaiq

hotov

p Zone

L) ique (H acoust ection de corr Zone

F

G

H

074

Stadium

Appui néopréne Détail 8

PARAMETERISATION To set these geometrical constraints, we used Rhinoceros and Grasshopper parametrical software. At the same time, we set a number of ­parameters that allowed us to precisely control the shape of the roof in the subsequent stages of the project and adapt it during the six months of design development that followed. In the meantime, using information from the parametric model, we checked the resulting dimensions and roof slopes against the dimensioning criteria for the secondary structure and membrane cover. At the macro level, the shape of the intrados sur-

face was controlled by the position of the circular arcs and the number of divisions per arc. The ­position of the circular arcs also gave the locations of the roof support points on the concrete stands. These parameters therefore controlled the number of repeated elements, the shape of the roof and the interfaces between roof and stands. At the micro level, parameters were set to control the aspect of the section. They also ­influenced the structural efficiency of the truss, the relationship between primary and secondary structures and the slope of the membrane cover.

MEMBRANE COVER The stadium is covered by 25,000 m2 of ETFE and is one of the first structures to use flat, ­single-layer ETFE over such a large area. Due to the material’s relatively recent appearance in France, ETFE structures are not yet covered by any regulations and the existing codes for fabric structures are not fully applicable. Rather,

E  axonometric projection of a curved half-frame

F steel components of the end connection joint for “threaded­-through” timber members with a thinner cross section

075

nice (FR)

G steel components of the end connection joint for timber members with a thicker cross section.

they are considered as cladding systems and therefore have to be approved by obtaining an “avis technique experimental” (ATEx), which ­requires experimental tests to be performed. We developed a method to justify the ETFE, which eventually led to biaxial tests to verify the allowable stress in the film.

H end connection joints for timber members with a thicker cross section after installation.

Architects Tectoniques Architectes, F-Lyon (FR)

Structural engineers Arborescence, F-Lyon (FR)

Sports Hall in Rillieux-la-Pape 1

076

2

4

5

077

3

aa

bb

a

b

2

1

b

9

6 8

7

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a

site plan scale 1:3,500 sections floor plan scale 1:500

078

1 multipurpose sports hall 2 gymnastics hall 3 administration office 4 foyer 5 public WC 6 refuse room

Sports Hall

7 security office 8 vestibule at entrance area 9 spectator stand

3

The Hacine Cherifi gymnasium is the latest addition to the Paul-Chevallier school complex in Rillieux-laPape, to the north of Lyon. Directly adjacent to two existing buildings, the double-court gymnasium defines the north-east limit of the school site. It was named in honour of the former world champion boxer of the same name, who grew up in the town. Internally, the Douglas fir clad building combines a 1,100 m2 multipurpose sports hall and an 800 m2 gymnastics hall, which are arranged in an L-shape around a glazed entrance area, including a cafeteria. The equipment and locker rooms are located on the floor below. To limit the ­adverse effects of the 9 –12 m tall building on the neighbouring residential area, the architects buried part of the new building into the inclined ground on the site. The designers ­selected the materials for the interior on a floor-by-floor basis: the bottom three metres of the hall including the 400seat spectator stands are constructed in fair-faced concrete; above this the structure is built completely in timber. The atmosphere in the two halls is set with light wooden tones and the grey of the fair-faced concrete. A clear contrast is provided by the gymnastics equipment, for which, without exception, the architects have chosen the colour fire brigade red. Sophie Karst

079

Rillieux-La-Pape (FR)

Text Laurent Clère Linçoir GL24h - 140*360 Linçoir GL24h - 140*360

2900

12218

5800

9386

5800

6134

5800

580

A

Linçoir GL24h - 140*360 Linçoir GL24h - 140*360 12218 12218

2900

5800

5800

Linçoir GL24h - 140*360 Linçoir GL24h - 140*360 9386 9386

6134 6134

5800

5800

Panne GL24h - 140*360

Panne GL24h - 140*360

2900 2900

5800 5800

B

Panne GL24h - 140*360

5800 5800

au GL24h - 200*540 520

2570

140

5800 5800

Linteau GL24h - 200*540

2570

520

2570

140

520

140

520

2570

140

Linteau GL24h - 200*540

2570

520

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140

2570

140

Linteau GL24h - 200*540

2570

520

2570

140

271

Panne GL24h - 140*360

520

2570

140

Linteau GL24h - 200*540

2570

520

2570

140

2710

360

Panne GL24h - 140*360 Panne GL24h - 140*360 Lisse GL24h - 140*360 Lisse GL24h - 140*360

Lisse GL24h - 140*360 Lisse GL24h - 140*360

Panne GL24h - 140*360 Panne GL24h - 140*360

Panne GL24h - 140*360 Panne GL24h - 140*360

200

Panne GL24h - 140*360 Panne GL24h - 140*360

520

Linteau GL24h - 200*540

2570

Panne GL24h - 140*360 Panne GL24h - 140*360

C

Linteau GL24h - 200*540

2570

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Panne GL24h - 140*360

Linteau GL24h - 200*540

2570

140

Panne GL24h - 140*360

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au GL24h - 200*540 2570

520

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Panne GL24h - 140*360

5800 5800

Linteau GL24h - 200*540

2570

Panne GL24h - 140*360

Panne GL24h - 140*360

Lisse GL24h - 140*360

Lisse GL24h - 140*360

Panne GL24h - 140*360

Chevron 60*180 60*180 Linteau GL24h - 200*5Chevron 40 LinteCalage au GL+24 200*540 2h vis- Ø6/120

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140 140

2570 2570

520 520

2570 2570

140 140

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5600

520 520

Linteau GL24h - 200*540 Linteau GL24h - 200*540

Chevron 60*180

2570 2570

140 140

Linteau GL24h - 200*540 Linteau GL24h - 200*540

2570 2570

520 520

2570 2570

140 140

Linteau GL24h - 200*540 Linteau GL24Calage h - 200*540 + 2 vis Ø6/120

2570 2570

520 520

2570 2570

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2710 2710

360 360

Chevron 60*180 Chevron 60*180 Calage + 2 vis Ø6/120

Chevron 60*180

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Chevron 60*180

200

Chevron 60*180

5

3062

5

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3062

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3062

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60 630 60 630 60 630 60 630 60 630 60 630 60 630 60 630 60

Chevron 60*180 Chevron 60*180 Calage + 2 vis Ø6/120 Chevron 60*180

D

Calage + 2 vis Ø6/120

Chevron 60*180

5600

Queue d'aronde adaptée suivant appui Chevron 60*180 Tôle - 8mm Chevron 60*180

Tôle - 6 mm

Calage + 2 vis Ø6/120

200 200200 5600 5600

5

3062

5

3062

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80

Chevron 60*180 Chevron 60*180 Chevron 60*180 Calage + 2 vis Ø6/120 Calage + 2 vis Ø6/120Chevron 60*180 Chevron 60*180

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3075

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Chevron 60*180 Chevron 60*180

11

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2

Chevron 60*180 Chevron 60*180

80

2*2 boulons Ø16

Calage + 2 vis Ø6/120 Calage + 2 vis Ø6/120

Chevron 60*180 Chevron 60*180

Pour les files C à H

2*4 boulons Ø16 Chevron 60*180

Calage + 2 vis Ø6/120 Calage + 2 vis Ø6/120

Chevron 60*180

80

200200

Chevron 60*180 Chevron 60*180 2791 2791

5 5

3062 3062

2*3 boulons Ø16 5 3062 5

3062

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3062 3062

5 5

80

48 64 48

080

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Tôle - 6 mm

80

48 64 48

80

Epaulement adapté suivant appui Tôle - 8mm

Chevron 60*180

2791

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Chevron 60*180

60 60 630630 60 60 630630 60 60 630630 60 60 630630 60 60 630630 60 60 630630 60 60 630630 60 60 630630 60 60

80

Chevron 60*180

Sports Hall

80

23062 11 3062

5 5

3062 3062

5 5

3062 3062

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3062 3062

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2*3 boulons Ø16 2*2 boulons Ø16 Pour les files C à H

3062 3062

5 5

3062 3062

5 5

3075 3075

3062

5

200

2791

5

307

Based on the experience with earlier projects, the architects again used a hybrid construction of timber and concrete, which is almost

­ ompletely visible from the interior of the c ­building. The timber elements were mainly ­prefabricated.

ROOF CONSTRUCTION The main structure takes the form of plywood ­trussed girders spanning 33.66 m and 27.54 m in the small and large hall respectively and ­supported on glued laminated timber columns

at 5.8 m c ­ entres. The prefabricated roof girders were all delivered in two parts, which were connected ­together on site and lifted into their final positions by crane.

COLUMN SUPPORTS The glued laminated timber columns on the west facade are supported on the 3.75 m high concrete wall. On the eastern side, the

­ olumns are supported on the reinforced c ­concrete floor slab above the top of the rows of seats.

E Diago de stabilisation

Diago de stabilisation

C  plan view of roof frame construction in bottom chord plane with ­diagonal crossed struts, scale 1:200

A  section north facade, scale 1:200 elevation short trussed girder and column spacing in facade stiffened with crossed diagonals

B section east facade, scale  1:200 section through top and bottom chord level roofs, elevation of double columns stiffened with crossed diagonals

081

Rillieux-La-Pape (FR)

D  crossed strut ­connection  details with steel plate ­strengthening scale 1:20

E axonometric complete structure

1

2

3

4

1

5

6

7

vertical section through roof and facade  scale 1:20 1 roof waterproofing: PVC membrane 160 mm thermal ­insulation; vapour

barrier 22 mm veneered plywood board 170/70 mm rafters 25 mm ­wood wool acoustic panel 2 200/450 mm trussed girder top chord

082

Sports Hall

3 170/70 mm transverse timber beam 4 180 mm glulam truss diagonal 5 2× 90/720 mm trussed girder bottom chord

6 63 mm Douglas fir 19 mm 3-ply plywood 27/38 mm h ­ orizontal laths; 38/38 mm ­vertical laths ­membrane; 35 mm wood wool light­weight building board

360/140 mm cross beams, b ­ etween them 360 mm straw bale thermal ­insulation in timber framing vapour barrier 18 mm OSB

120 mm vertical laths 19 mm 3-ply spruce plywood 7 160 mm PU thermal insulation water­proofing layer; 360 mm ­reinforced concrete

STIFFENING The large hall is stiffened horizontally by ­diagonal cross struts in solid wood that span ­between the rafters of every roof level. The ­facades and the inner frame construction are stiffened vertically by steel cross bracing with turnbuckles to transfer the horizontal

loads into the reinforced concrete base. The ­trussed girders are stiffened transversely by timber frames connected to the double ­columns of the eastern facade. The column bases are cast into the concrete base to form a moment connection.

EXTERNAL WALLS The 2,000 m2 opaque facade consists of ­non-­load bearing 36-cm thick prefabricated OSB box elements filled with straw bales. The

F

G

F connection principle for the two halves of a trussed girder scale 1:50

G  detail principle for assembly of double columns on steel bracket  scale 1:50

083

Rillieux-La-Pape (FR)

walls were boarded on both sides with three-­ layer p ­ lywood panels, the interior layer being spruce and the exterior Douglas fir.

Architects Rossetti + Wyss Architekten, Zollikon (CH)

Structural engineers Lüchinger+Meyer ­ auingenieure, Zurich (CH) B

Garage and ­Vehicle Workshop in ­Andelfingen

084

085

aa

bb

a

b

b

a

sections, floor plan scale 1:500

layout plan scale 1:2,500

axonometric

086

Garage and ­Vehicle ­­Workshop

The log cabin principle has proved itself over several millennia. The 480 m2 garage and workshop in Andelfingen near Winterthur shows that this form of construction also works on a large scale. The ­column-free hall at the Neugut water services depot provides space for six large vehicles or machines. Some 29.7 m long and with a clear headroom of 7.6 m, it a ­ llows mobile cranes to work inside unobstructed. At the front, the roof cantilevers well over the forecourt and shelters people working there. Assembled from 36 glued laminated timber wall members with interlocking c ­ orner halvings, the construction very closely resembles that of a traditional log cabin. The “logs”, which are up to 32 m long, were prefabricated from Swiss spruce, delivered on semi-trailers and fitted together using a pneumatic crane in only four working days. Interlocking corners, the largest ever manufactured, secure the structure against overturning and ­longitudinal displacement. Kept in place by vertical steel pins, the logs are slightly offset to one another so that the building widens with height. Drip notches are routed into each projecting edge on site, allowing rain water to drip off as it does from shingle cladding. The narrow lengths of wall on each side of the door ­elevation stabilise the structure in the longitudinal direction, thereby reducing the span and the structural depth of the timber beam over the door opening. The timber roof has a rubber waterproofing membrane.  Florian Köhler

087

Andelfingen (CH)

Text Andreas Koger

A

2

3

1

4

A 5

6

7 8

+0

+10

3110 3110

+80

12830

10 mm linear precamber

A  facade profile side wall, scale  1:20

bb

+10

12830 25660 31880 70 mm parabolic precamber

1 150/30 mm spruce fascia 2 0.5 mm stainless steel sheet; suspension

profile; 100/135 mm squared timber, spruce 3 prefabricated roof board: 1.5 mm rubber waterproofing membrane; 1 mm nonwoven separation layer

80 mm laminated veneered lumber to 1.5 % falls 4 2100/240 mm spruce ­glulam prefabricated wall members

088

Garage and ­Vehicle ­­Workshop

5 240 mm long Ø 35 mm steel pins 6 10/10 mm groove drip edge 7 concrete plinth wall, high accuracy, ±2 mm vertical tolerance

+0

1950

B

3110 3110 10 mm linear precamber

8 30 mm heavy-duty ­concrete screed 250 – 330 mm reinforced concrete floor slab to falls, smoothed, sealed 50 mm lean c ­ oncrete

B view of main beam scale 1:250

STRUCTURE The 32-m long main supporting beam over the entrance doors plays a key role in the load­ bearing structure. The 2-m high, 24-cm thick beam spans the 25-m wide wall opening and has to carry almost half the roof load. Approximately half the 72-mm calculated deflection of the beam was due to self-weight and the roof load, and was expected to take place ­immediately after erection. This was confirmed

C

D

089

Andelfingen (CH)

by on-site measurements. The remaining 36 mm allows for the additional deflection under snow loads and the long-term creep of the wood. The beam had an initial precamber of 80 mm, which provided an 8-mm reserve. All components were assembled horizontally, on their sides. The decision not to work with the members standing vertically ­allowed the timber to expand, contract and shrink freely.

Architects HCMA Architecture + Design, Vancouver (CA)

Structural engineers Fast+Epp, Vancouver (CA)

Sports and Leisure Pool in Surrey

090

091

aa

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12

15 4

upper floor

b a 9

3 3

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2 8 c

5 4

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ground floor

  8 competition pool   9 training room 10 store 11 deliveries 12 fitness room 13 plant room 14 spectator stand 15 springboard

sections floor plans scale 1:1,000

1 entrance hall 2 pool attendant  / first aid 3 changing rooms 4 water slides 5 leisure pool 6 sauna / steam bath 7 heated pool

092

Sports and Leisure Pool

The Grandview Heights Aquatic Centre (GHAC) has a vital role as a magnet for families, water sports enthusiasts and international competitions in the rapidly growing city of Surrey, Canada. The architects developed a concept that maximises the area of glazed surfaces to visually connect internal and external spaces. With its 50-m long competition pool and d ­ iving platform, the facility complies with all the standards required to host regional, ­national and international sporting events. In addition, it also offers leisure pools, heated pools, water slides, saunas and steam baths, as well as a fitness centre on the upper floor. An extraordinary suspended roof in timber spans the swimming pool. It creates a feeling of warmth and achieves the required headroom with a very shallow structure. The modest building volume keeps the costs of the building envelope and air-conditioning within limits and combines user comfort with energy ­efficiency. Andreas Gabriel

093

surrey (CA)

Text Paul Fast, Derek Ratzlaff

C

A

internal forces only in facade plane

support reactions

45 m

55 m

B

2

1

1

094

Sports and Leisure Pool

2

2

UNCONVENTIONAL STRUCTURAL ENGINEERING ­CONCEPT The long-span timber suspended roof of the GHAC demonstrates the potential of wood as an inexpensive, structurally efficient and ­aesthetically pleasing material for the construction of swimming pool buildings. The architects proposed a longitudinally spanning roof. We suggested a slender, lightweight suspended roof with “cables” manufactured from glued laminated timber (GLT). After some initial scepticism, the architects decided in favour of our unconventional approach after we had demonstrated the advantages of timber in conditions of high air moisture content and the effects of chemicals used in swimming pools. The suspended construction has a structural depth of only 300 mm. Initial analyses quickly led to the introduction of V-shaped central supports between the two large pools to minimise complexity and cost. Pairs of 13 cm × 26.6 cm GLT profiles at 80 cm centres span

D

A structural system

E

B RC columns with ­foundations and pre­ stressing ­elements scale 1:400 1 675 × 1000 mm concrete cross section

095

the 55 m and 45 m gaps between the central ­supports and seven ­reinforced concrete ­columns at each end of the building. A double layer of 16 + 12-mm thick p ­ lywood boards is ­attached to the tops of the GLT “suspension cables”. RC edge strips pick up the ­tensile forces from the suspension members and transfer them into the central and outer ­supports. Slab foundations acting with the backfill secure the columns against overturning. ­Originally, the variably sloping roof geometry in the transverse direction led to 14 different radii for the GLT “cables”. We adjusted their lengths so that they all had the same radius of curvature. The steel tubular columns connecting the up to 20-m high facade structure to the roof are perforated and serve two functions: they carry the wind loads and act as integrated supply air distributors, largely­dispensing with the need for internal ducts.

surrey (CA)

with 6× Ø 46 mm threadbars 2 700 × 1200 mm concrete cross ­section with 6× Ø 46 mm threadbars

F

C deformation under uneven loads

D – F  structural principle of the roof

G 3 ≤10° 3

1

2

1

≤10°

4 220

2 4 120

280

280

120

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280 6

120

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2075

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220

H

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263

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120

266

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61 50 61

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8

130 130 28 266

61 50 61

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340

280

120

120

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280 1

120

5 9

6

130

2075

130

280

61 50 61

1

120

225

Sports and Leisure Pool

62

7

28

096

DEFORMATIONS Suspended structures change their shape in ­response to the load placed upon them and are particularly sensitive to varying, unevenly dis­ tributed loads. Initial calculations for an uneven snow load showed vertical deformations of up to 1200 mm. However, the aim was to limit this

to the manageable size of 200 mm, which was within the capacity of a proven sliding facade connection. The designers solved the problem by stiffening the supports and ­reducing the ­unevenness of the distributed loads from slipping snow by fitting snow ­retainers to the roof.

WIND UPLIFT The relatively light timber structure does not have enough self-weight to prevent wind u ­ plift. Dismissing additional imposed load or steel cable stays inside the building, we ­designed the GLT members

as flat inverted compression arches to accommodate any possible wind uplift forces. In addition, a shear-transmitting connection of the boards with the GLT members provides composite action.

DYNAMIC BEHAVIOUR From the location, orientation and shape of the building, it was likely to be exposed to wind oscillations with a frequency of less than 1 Hz. In order to avoid vibration risks, the natural ­frequency of the roof structure needed to be

above 1.5 Hz. A 3D analysis estimated it to be 1.35 Hz. The calculations were checked by taking measurements on site with a metronome and accelerometers at a “jumping party” of test people and confirmed as 1.7 Hz.

ERECTION AND CONNECTING ELEMENTS Erection had to be completed quickly to protect the wood from rain. Transport restrictions limited the length of the GLT members to 25 m. The shorter span therefore required one on-site longitudinal joint, the longer span two. To save time, longitudinal joints consisting of 22-mm thick

G  column head ­reinforcement scale 1:50

097

H GLT cross section I GLT connection

surrey (CA)

J on-site connection scale 1:20

steel plates were each connected to two pairs of GLT members by a total of six bolts. A lifting frame was used for the short span while the long-span beams were lifted with two cranes. The whole roof including the plywood layer was erected in 12 days.

1 266/130 mm GLT profile 2 140/52/180 mm GLT block every 5 m 3 12 + 16 mm glued plywood boards

4 800/220/6.4 mm ­galvanised bolted steel plate 5 Ø 25 mm bolts 6 200/22 mm steel plate 7 Ø 57 mm bolts

8 350/280/30 mm steel plate 9 225/200/16 mm steel plate

8

d 2

d

9

10

2

3

11

1

4 6 5

7

dd

Vertical sections scale 1:20  

098

1 266/130 mm GLT profile 2 synthetic water­ proofing membrane 12 mm woodbased board 100 mm insulation vapour barrier

12 + 16 mm plywood board 3 sliding connection steel plate with ­elongated holes 4 2.4 mm aluminium plate 175 mm flexible

Sports and Leisure Pool

­insulation, silicone seal 5 138 mm poly­carbonate cellular sheet 6  ¡ 155/105 mm steel tube 7  ¡ 410/310 mm ­perforated steel tube post

8 285 – 425 mm ­reinforced ­concrete 9 75 mm aluminium panel with ­insulation 130 mm ventilation cavity 2× 25 mm ­ acoustic panel

10 | 150/150 mm steel tube 11 insulation glazing

099

surrey (CA)

Architects Eberhard Wimmer Architekten, Munich (DE)

Structural engineers Sailer Stepan und Partner, Munich (DE)

St. Josef ­Parish Church in H ­ olzkirchen

100

101

aa

4

1

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a

2

9 7 8 6 4 4 section, floor plan  scale 1:500 site plan a scale 1:3,000

102

1 1 church 2 chapel 3 foyer 4 vestry 5 clock tower (­existing) 6 rectory (2nd phase)

3 7 parish office (2nd phase) 8 parish community 3 centre (2nd phase) 9 parish community hall (existing)

St. Josef Parish Church

1 2

a

5

2

An extraordinary timber structure defines the atmosphere inside the new St. Josef Church in Holzkirchen. Its predecessor, built in 1962, had become structurally unsound due to serious construction defects. Because refurbishment had been shown to be uneconomical, the client issued an architectural design competition for the redesign of the whole parish centre complex and the construction of a new parish church (400 seats) with a weekday chapel (50 seats). The competition documentation e ­ xpressed a wish for a timber structure. The successful architect’s design envisaged an open, inviting group of buildings that incorporated the existing church tower. Church and chapel stand opposite one another and take the form of two differently sized and inclined truncated cones with an elliptical footprint and rooflight. They are linked by a flat roofed vestibule, which is connected to the vestry and a covered path to the northern part of the parish centre complex. The interior of the church expresses a contemporary interpretation of the liturgy with a centrally positioned altar. The conical building ­envelope clad on the outside with wooden shingles encloses the church’s interior and is both a roof and a wall. The rooflight and flat side window, as planar interface surfaces, differentiate themselves from the geometry of the building’s basic form and bring the 20 m high space to life with an exciting combination of light entering vertically and horizontally. Following dedication of the church, the community has access to a sacred space with a special aura. Andreas Gabriel

103

Holzkirchen (DE)

4

Text Peter Mestek

A

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Fl. 40x50

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Ring

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Bl. 20x410x655

Diagonale

Bl. 20x410x655

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50 70 70 2050 20

250

25

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1

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4

Fl. 10-40x50 Bl. 20x390x730

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20 20 50 20 20 70 70 50 50 70 70 50

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Ring 4

Ring Fl. 40x50

Fl. 10-40x50 245Bl d=25 4 10 30 10 30 85

Fl. 10-40x50

104

Fl. 40x50 Bl. 20x390x730

Diagonale

20 20 50 70 70 50

Bl. 20x410x655

3

315

Bl. 20x410x655

Fl. 40x50 4x Rd 80

Bl d=25 4 St. Josef Parish Church

655 80

265

310 Bl d=25

Bl d

Fl. 4

Ring

Fl. 40x50 3

245

410

250

30 10 85 3010 Bl d=25

325 4045 105

250 50 70 70 2050 50 70 70 2020 50 20

7

5

157 B

3

40

5

157

20 20 50 70 70 50

157

710

5

40

5

157

5

B

TWO DIFFERENT STRUCTURES Although the church and the chapel are both ­inclined truncated cones, their load-bearing structures are remarkably different. The main structural element of the chapel comprises glued laminated timber (GLT) beams running in the principal direction of fall of the cone sides and restrained by a flexurally stiff ring at the crown of the roof. The system is stiffened by ­exterior wood composite board cladding. At

the large window opening, the beams are not supported on the ring foundation, but are connected to a parabolic, block-glued GLT arch. The arch’s horizontal deflection was calculated using a 3D analysis to design the components and their connections. The result was that GLT rings, flexibly stiff to resist transport loads, were attached at the beam third points to stabilise the main structure of the chapel.

CHURCH MAIN LOAD-BEARING STRUCTURE The church has an elliptical floor plan with a ­diameter of approximately 34.5 m and a height of 21.6 m. The structure is terminated at its highest point with an inclined rooflight constructed from a slender steel grillage. The dissolved, ­exposed shell construction is composed of GLT struts, which form triangles and therefore fulfil stiffening and load-bearing roles. The corners of the triangles meet at nodes at the inter­sections of the fall lines of the cone with the differently inclined intersection planes. Thus the structure has approximately 350 of these nodes, which are normally a mirrored arrangement of two

E

A  determination of the node positions

105

­adjacent triangles. The elliptical rings within each intersection plane are one-piece, curved GLT beams with flexurally stiff joints. The diagonally running struts were ­initially idealised as members of a pin-jointed truss in the early 3D calculation model. However, they were predominantly loaded in compression and therefore later modelled as pure compression members that would fail under tension, in order to optimise the connections. The diagonals are kept in place by steel tie rods spanning between two adjacent rings at regular intervals and following the principal direction of fall lines.

F

B  detailed section of a ­standard node scale 1:20

C vertical section through a special node at the side window scale 1:20

Holzkirchen (DE)

D node with steel tie rods

E  standard steel i­n-built node ­component

F  special beech LVL ­in-built node ­component

G 3171

77

789

227

410

863 712

73

519

3171

470

H

807

525

82

557

40

220

10

40

200 220

10 150

40

15 20

G  horizontal section of the roof with pre­fabricated vaulted elements acting as the subconstruction for the wooden shingle cladding scale 1:50

106

525

H  detailed sections at base point  scale 1:20

807

82

St. Josef Parish Church

150

186

200

7

150 150 10

50

550

755

58 81 20 00 el 1 0 60– 200

iab

150

87 2

50

200

7

10 150

100

160

50 70 90 80 20

24 Var

40

NODE CONNECTION DESIGN As a result, the connections at the nodes could be designed to transfer the normal forces in the diagonals by contact pressure only. At the standard nodes, steel wedges were welded onto the steel baseplates on the top and bottom faces of the rings. The ends of the diagonals, on the other hand, were shaped to the negative form of the steel connection surface by CNC machines. Fabrication drawings were produced by the timber construction company based on

a 3D computer model containing not only all the timber components, but also all the steel parts and fastening materials, to ensure that the required extremely high ­degree of accuracy of fit was achieved. Steel cylinders through the rings connect the baseplates and transfer the forces from the upper to the lower diagonals. For aesthetics and fire protection – an R30 rating applied to the load-bearing structure – all the connection fittings were concealed.

SPECIAL SOLUTIONS The timber construction company submitted a special proposal for the upper, more lightly loaded nodes. This enabled 245 of the “steel” nodes to be replaced by prefabricated

107

Holzkirchen (DE)

pieces of beech laminated veneered lumber (LVL). The roof elements were also prefabri­ cated to minimise the possible effects of the weather.

Architects Robertneun Architekten, Berlin (DE)

Structural engineers Assmann7Beraten + Planen, SD ø10mm Hamburg (DE)

Delicatessen Wholesale Store in Stuttgart 36 SD ø10mm

270

270

40 50 50 50 50 30 40 70

0 40 7 20 0 30 5 0 3 0 50 5 0 4

40 50 50

20

20 40 5 0 50 30 592 50

50 50 50 50 5

133

HEA-140 S355

108

50 50 40

100

30 50 50 50 50 40 50 50 50 50 50

140

9 SD ø10mm

140 14 0

9 SD ø10mm

520

50 40 50 50 50 50 30

109

50 50 50 50 50 40 50 50 20 50 50 50

100

The client, a delicatessen wholesaler and retailer, has a large number of “FrischeParadies” outlets all over Germany. Every branch has an individual character and is designed to ­integrate into its urban surroundings and fulfil its role in the food and produce cycle. In the case of the company’s new premises in a heterogeneous commercial area in Stuttgart, the building has two important usage areas: retail space for private customers and a wholesale area in which goods are delivered, stored, allocated to orders and sent out to customers such as restaurants or hotels. The architect translated these requirements into a homogeneously structured building with a series of four spaces that allow an optimum operational flow and correspond with the need of the client to provide customers with a ­high-quality purchasing experience. A particular source of inspiration for the design was the sawtooth roof of a neighbouring wholesale fruit and vegetable market. The most important and most prestigious building component faces the road and the car park and houses a spacious market hall. As the only area accessible to customers, this building forms the

11

11

first floor

5 4 2

10

1

3

6

8

5 4 10 9

7

2

7

ground floor 8

floor plans  scale 1:800

110

  1 main entrance 9   2 market hall   3 fish market   4 chiller room for fruit / vegetables   5 bistro kitchen

3

6

  6 chiller room 7   7 delivery area   8 order picking   9 dispatch 10 dry store 11 offices

7

­Delicatessen ­Wholesale ­Stor

1

starting point for the design and not least the characteristic roof structure. The client wanted the visible parts of the structure to have a distinct materiality and create a pleasant room atmosphere that would cast the fresh food in the right light. This requirement quickly led to the choice of wood. The architects and engineers developed a concept of transverse reinforced concrete walls supporting a long-span timber truss roof structure that, with no intermediate secondary supports, spans the building’s floor areas in four typologically identical sections of different widths. “Caps” set centrally on the roof in the ridge area admit high levels of daylight and provide natural ventilation. The overall ­result is an appropriately scaled building that clearly expresses the four usage areas externally: market hall, cold store with office above, order picking hall, dry store. During the tender process, the timber construction contractor was able to optimise m ­ aterial thicknesses in the roof structure, which resulted in large cost savings and the creation of a yet more slender and elegant timber truss system. Roland Pawlitschko

111

Stuttgart (DE)

Text Henning Klattenhoff

112

­Delicatessen ­Wholesale ­Stor

ROOF STRUCTURE OF FRISCHEPARADIES STUTTGART The first approach to the design of the Frische­ paradies roof structure in Stuttgart involved four barrel segments, each of a different r­adius, and a desire from the beginning to have the underside look to be made of wood. However, the large amount of material required and the limiting radius to which glued laminated timber could be manufactured led to the development of an alternative based on timber trusses. As the development of the design for the hall progressed, the architect settled on a form made up of inclined roofs with “hovering” flat

roofed areas at the ridges and bands of windows at the sides – the heights of the ridges and the high and low points of the sloping roof are the same for all the hall segments. The trusses had to be made from the same-sized timbers and each of the spans had to follow the same system. The trusses were made continuous because a series of single-­span simply supported trusses would have ­resulted inexcessive deformations of the roof skin, ­culminating in cracks at the ­valleys and making effective waterproofing difficult to achieve.

TRUSS WITH ADDITIONAL UNDERSPANNING CHORDS The structural analysis of this system and the stipulated frame of reference led to a rather atypical form of truss, which had underspanning chords for the longer-span roofs in addition to the traditional top and bottom chords: the moments from the roof loading are carried by three instead of the usual two chords. Because the bottom timber chord in the largest hall is then predominantly under compression forces,

lateral ties were necessary parallel to the ­longitudinal axis of the hall to provide buckling ­restraint. The slender third points in the timber trusses were also stabilised by the top chord bracing in the skylight and by the crossed ­underspanning ties below. The higher loads from the green roof and snow required the use of cross-laminated ­timber for the roof skin.

EARLY INVOLVEMENT OF THE TIMBER CONSTRUCTION CONTRACTOR The structural engineers arranged, through the client, for a specialist carpentry company with a great deal of experience in roof structures to become involved at an early stage, so that the timber structure could be made more cost-­ effective almost from the start. The carpentry company also assisted the architect in the preparation of the tender documents and advised the structural engineer about the economic aspects of the choice of connections. The subsequent appointment of a general contractor resulted in the choice of a ­different specialist carpentry company. The involvement of Holzbau Amann ­resulted in several further modifications and

113

Stuttgart (DE)

manufacturing-­related improvements: in ­particular, a higher grade of cross-laminated timber and reductions in the amount of transverse stiffening allowed the cross section of the chords to be slimmed down such that there was no need for block gluing. Additional working butt joints were detailed in the ­trusses and the number and dimensions of ­slotted plates and dowel rods adjusted. These optimisations proposed by the timber con­ struction contractor i­llustrated the benefits of having a precise analysis and detailed knowledge of structural engineering design, building physics and the effects on the asso­ ciated works.

A

280x

280x240/GL24h-si

280x360/GL24h-si 360/G

L24h

-si

280x

360/G

L24h

280x360/GL24h-si

280x360/GL24h-si

-si

280x360/GL24h-si

280x240/GL24h-si

280x240/GL24h-si

160x600/GL24h-si 200x280/GL24h-si 240x240/GL24h-si

3726

3726

-s

i

-si

3774 11250

2h

240x240/GL24h-si

L3

4h-s

i

S355

3750

36

280x320/GL32h-si

0/G

L3

2h

-si

3774

2h

0/G

GL2

HEA-1 40

S355

L3

32

320/

0/G

0x

280x

36

28

U-80 S235

U-80 S235

S235

HEA-140 S355

11250

114

U-80

U-80

0x

2h

3750

-si

28

-s

i

36 280x

GL2 360/

4h-s

L3 0/G

2h-s

280x

360/ GL2

i 280x320/GL32h-si

280x 360/G

280x240/GL24h-si

4h-s

i

280x240/GL24h-si 160x660/GL24h-si

160x720/GL24h-si

280 x36 0/G

L32

280x360/GL24h-si L24h -si

360/G 280x

-si L24h

280x200/GL24h-si

DN=18.7°

DN=15°

0x 28

32

0/G

L3

2h

-si

28

0x

2x160x280/GL24h-si

32

0/G

L3

2h

8750

­Delicatessen ­Wholesale ­Stor

-si

280x

360/G

3060 2773 2917 8750

3750

L32h

-si

G 320/

280x

DN=15°

280x320/GL32h-si

-si L32h 360/G

h-si

280x

2564 2371 2564 2917 2773 3060 7500

i

L32h

240x240/GL32h-si

L3

40 HEA-1

L32h

280x 360/G L32h 240x240/GL24h-si -si

0/G

280x

G 320/

240x240/GL24h-si 280x320/GL32h-si

280x

200x280/GL24h-si

32

240x240/GL24h-si

240x240/GL24h-si

240x240/GL24h-si

160x720/GL24h-si 200x280/GL24h-si 28 0x

0x 28

-si L32h 360/G 280x 240x240/GL24h-si

DN=39°

DN=15°

HEA-14

HEA-140 S235

HEA-14

0 S235

3774 11250

240x240/GL24h-si

0 S235

3726

3726

3774 11250

280x 32

-si

3750

i h-s

2

0/G

L32h -si

-si

L24h

360/G 280x

L3

0/G

32

0x

28

320 1976 1914 4230

B 5 SD ø10mm

9 SD ø10mm

7 SD ø10mm

9 SD ø10mm 36 SD ø10mm 270 30 0 70 20 50 4 30 0 50

270

40 50 50 50 50

40 70 30

40 5

100

592 50 133

50 50 50

A layout drawing section middle truss scale 1:50

30 50 50 50 50 40 50 50 50 50 50

140

520 50 50 40 50 50

50 50

30

50 50

50 50

50 40 50

50 50 50

50

20 100

B vertical section middle truss scale 1:20

100 20

HEA-140 S355

9 SD ø10mm

450

115

Stuttgart (DE)

10

20 50 3 0

200 20 20

40 50 50 50 50 40 20

40 50

6 SD ø10mm 140

Architects EM2N Architekten, Zurich (CH)

Structural engineers Schnetzer Puskas Ingenieure, Zurich (CH)

3

Heuried Sports Centre in Zurich 5

4

116

1

117

Alterations and extension works at the Heu­ried Sports Centre in Zurich took two years. It opened again in autumn 2017 with a new ice rink. The centre’s open-air swimming pools have been available since the 2018 season. In the light of structural and operational problems, the city council issued an ­architectural competition for the refurbishment and upgrading of the original open-air facility with its swimming pool and two outdoor ice rinks built in 1964 to a design by Fritz Schwarz and Hans Litz. The winning entry by locally based architects EM2N involved refurbishing the sports centre and adding a ­year-round ice rink. The design skilfully combined the different uses in one building beneath a striking, three-part roof landscape with photovoltaic panels. The impressive c ­ anopy with its large skylights cantilevers 16 metres to shelter the entrance zone below, which connects to and links the various levels. Ramps, stairs and footbridges enrich the experience for visitors to the complex in an interplay with planted and landscaped areas, continuing the tradition of modern open-air swimming pools in Zurich. The roof and external ­facade are constructed in timber. A continuous ribbon of windows on the upper floor provides a visual separation between the body of the building and the roof, which forms a modu­lated landscape to suit the flow of forces in the beams. White and grey timber laths envelop the predominantly solid facade at ground-floor level. Their delicate proportions lend a certain lightness to the building. Heike Kappelt

aa a

2

1

3

a section scale 1:500

118

layout scale 1:1,000

1 outdoor ice rink 2 indoor ice rink in new sports hall 3 restaurant, technical rooms and lockers

Heuried Sports Centre

119

Zurich (CH)

Text Johannes Dudli, Oliver Bopp

A

B

2

3

4

1

7 5 6

120

Heuried Sports Centre

COMPLEX TIMBER ROOF CONSTRUCTION The building, which is split into two parts struc­ turally, is defined above all by its extra­ordinary timber roof. The rear part of the new building contains the ice rink. Eight double glued laminated timber beams, 35 m long, 480 mm wide, up to 2.4 m high and weighing 18 t, manufactured from spruce and fir span the 29 m wide rink and the spectator stands. They are supported on concrete columns at the outer wall. The beam spacing is 7.10 m. Acting as the substrate for the roof construction, 160 mm deep hot-dip galvanised trapezoidal section sheet-metal panels rest directly on the beams. The sheets are perforated to optimise the hall acoustics. Because columns

in the area of the spectator stands would have been obstructive, support to the beams was ­arranged with a structural engineering design sleight of hand: a “strip” formed by a series of timber and metal strut and tie frames bridges the 3.5 m gap between the roof beam ends and the concrete columns behind the spectator seating. Each of these frames is “back hung” off the concrete parts of the structure in front of the hall and creates an intermediate section of connecting single pitched roof. The roof void over the spectator seating also provides enough space for the building services installations, which are concealed behind a naturally finished larch ceiling.

16-METRE CANTILEVER Beams with a length of 32 m and a height of up to 2.4 m form the second, somewhat shorter main area of roof over the restaurant and the entrance to the hall. This roof functions as an independent structure. It is supported on concrete columns and the solid concrete ceiling slab at the heart of the building and forms an exposed 16 m cantilever, completely free of ­intermediate supports. It is stiffened within the plane of the roof soffit. Cladding conceals the construction of the eight glued laminated timber and two steel beams, each 30 m long.

Together they form a slightly sloping single­ pitch roof supported on concrete columns. The beams rest on bearing plates halfway along their length and at the rear end, designed in such a way that the cantilevering canopy creates no uplift forces at the inner support and can simply be bolted down. On the sides of the building and at the corners, the cantilever is an ample 4.5 m. This is made possible by two plate girders that intersect one another at right angles forming a flexurally stiff moment connection (Fig. A).

REINFORCED CONCRETE FRAMES The whole roof structure rests on prefabricated concrete columns, the bases of which are built into foundations at ground floor level. The frame action thus achieved stiffens the building against horizontal loads. The walls and floors between the frame members were designed to be in-situ concrete. The access cores were concreted on site, as are the ­remaining self-supporting walls. ­Because of the poor ground conditions, the chosen in-situ concrete bored-pile solution

A Axonometric of structure. The cantilever is 4.5 m at the sides and corners. This is made possible by two plate girders that int­ersect one another at right angles forming a

121

flexurally stiff moment connection.

Zurich (CH)

B static structural system typical section 1 steel profiles 2 timber beam 3 concrete ceiling slab 4 concrete frame column

had to be designed around the grid of the ­existing columns to ensure an efficient, direct load transfer into the supporting soils. The new hall leads directly out to a connected terrace and sundeck. The spacious interface with the open-air swimming pools is formed by an elevated concrete slab walkway supported on columns. Access is gained along a curved set of in-situ concrete steps, which also create an impressive eye-catching feature.

5 stiffening concrete basement walls rigidly connected 6 piled foundation 7 concrete columns pinned ends (stiffened by transverse bracing)

1

2

section roof construction scale 1:75

1 roof construction: extensive planting 40 mm ­water retention mat; roofing membrane; 140 mm thermal insulation vapour barrier; trapezoidal sheets with

122

Heuried Sports Centre

160 mm insulation 2 480/max. 2400 mm glued ­laminated timber beam clad with timber laths 3 240/440 mm glued laminated timber beam

4 HEB 280 mm steel profile 5 Ø 72 mm steel rod 6 Ø 56 mm steel rod 7 320/320 mm glued laminated timber

3

6 1

7

5

4

123

Zurich (CH)

4500 4500

Architects Rogers Stirk Harbour + P ­ artners, London (GB)

4500 4500

Structural engineers Robertson Construction Group, Stirling (GB)

The ­Macallan Distillery in ­Aberlour

124

4500 4500

125

450

b

5 a

8

a

11

9

6

10

ground floor

b

7

5

4 3 1

2

basement floor

  8 exhibition area   9 bottle archive 10 tasting lounge 11 stills

section floor plans scale 1:1,500

1 visitor entrance 2 reception 3 shop 4 cask store 5 fermentation vessel 6 mash tun 7 delivery area

126

The ­Macallan Distillery

6

With a series of five artificial hills on a green roof, the new building for the Macallan Distillery blends into the Speyside landscape, an a ­ rea of northern Scotland well known for its whisky. The distillery intends to expand its c ­ apacity by one third with the new facility and shut down the old production building. The architecture and technical systems of this industrial building form an integral whole. The ­distillation process determines the linear arrangement of the similarly shaped modules, leaving the option for a later extension. Four domes arch over circularly laid out two-storey production units. Their basements, where many of the system components are installed, each contain eight large fermentation vessels, which project upwards through the annular grid frame of the ground floor. Here is the heart of the distillery – smaller circular groups of 12 stills. The southern dome is taller than the rest and marks out the visitor centre, which is entered from the reception area in the basement. A fire-resistant glass wall running transversely gives a view onto the production area. The whole production facility is managed and served from a series of function rooms at the rear and an open delivery area accessed by ramps. The front of the building opens to the landscape with a glass facade under the undulating roof edge.  Burkhard Franke

127

­Aberlour (GB

Text Paul Edwards

bb

A

B

GSA version 8.7 Copyright © Oasys 1985-2017 Macallan 229222 Wiehag Model (V10b00) LC 71 changed to -7 from -10 

It was noticed that the DL was not included for the majority of the steel frmaing 20/08/2015. 

A seperate loadcase was then added (L3) an is not considered in any of the load combinations. 

Gravity of the steelwork was also added to LC 2 which is included in load combinations. 

Discovered lists for 4101, 4102 and 4104 were incorrect. old lists deleted.8/9/2015

GSA version 8.7 Copyright © Oasys 1985-2017



Noticed perimeter frame connected to timber roof beam at grid ~6F. Now structurally disconnected. 17/09/2015

The Macallan Distillery 229222 Roof Model DL of steelwork added as gravity case 30/10/2015. File: 151030_Roof_Wiehag_Model8.gwb



4No. still house z-restraints removed as only applied to the temporary case. 29/09/2015 File: 151109_Roof_Wiehag_Model7 GS_List

Element list: all not PB30 to PB57 Part is excluded by volume Scale: 1:83.78 Isometric Scale: 1:102.6

Scale: 1:196.0 Isometric Scale: 1:240.1

Axial Force, Fx: 500.0 kN/pic.cm 125.7 kN

Axial Force, Fx: 5000. kN/pic.cm 1547. kN

75.53 kN 25.40 kN

1016. kN

-24.73 kN

484.3 kN

C

-74.87 kN

D

-47.18 kN -578.7 kN -1110. kN -1642. kN -2173. kN Case: C500 : ULS Envelope Signed absolute value of env.

-125.0 kN -175.1 kN -225.3 kN Case: L2 : Superimposed dead load roof Case: A2 : Superimposed dead load roof Contour case

z y

x

Program GSA Version 8.7 Copyright © Oasys 1985-2017 J:\200000\229000\229222-00 Macallan Distillery\4 In...\151030_Roof_Wiehag_Model8.gwb

Printed

11-Sep-2018

Page Time

1 16:26

z y

x

Program GSA Version 8.7 Copyright © Oasys 1985-2017 J:\200000\...\151109_Roof_Wiehag_Model7 GS_List mod_DL review_displacement check.gwb

section scale 1:500

128

Printed

A  starting point with five domes

20-Apr-2018

Page Time

1 15:56

B roof surface formed by overlaying with a “fabric”, bounded by a rectangular frame

The ­Macallan Distillery

C timber construction with 3 m grid & steel structure

D normal forces in a typical grid shell (blue = compression, red = tension)

STRUCTURAL ELEMENTS The new build for the Macallan Distillery combines a number of different materials into a single complex load-bearing structure. The building is founded on shallow foundations and has a ground-bearing slab in the main halls. This supports a steel structure principally composed of

five 3D frames, one over each area of production. The steel structure supports a modular green roof, 207 m long, 63 m wide and constructed in timber. The building has glass facades on the south and east sides.

ROOF FORM-FINDING The industrial process of whisky-making ­defines the repetitive layout of the roof: the modular, circular arrangement of the production units equates to five point-symmetrical domes which have their apexes above the stills. The hot air resulting from the processes rises under these artificial hills for controlled venting through roof openings. To create a continuous roof from a series of five domes (Fig. A), a “fabric” is draped over them in the 3D model. An elon­ gated rectangle represents the edge of the

deck and acts as a fix frame for the form-finding. The simulation of a uniform area load on the ­inverted roof surface creates a funicular line from which a cross section that is always under tension (or compression when not inverted) can be derived in the area of the domes. The roof ­surface is made up of the circular plan shape of the curved dome, which transitions into a complex free-form with an undulating edge (Fig. B). An orthogonal 3-m grid projected ­onto the surface generates the basis for the load-bearing structure.

STRUCTURAL CONCEPT The digital model is materialised in the form of a grid shell with straight, vertical beams. The ­decision to construct the roof out of timber was based on its light weight compared to steel, ease of working and its negligible thermal expansion. Under normal loads, the roof surface is mainly subject to longitudinal forces and bending ­moments, which timber is particularly good at resisting. With a structural depth of 750 mm, the roof has the necessary stiffness for resisting torsion arising from of out-of-balance loading. Each dome is supported by a 3D steel frame with an octagonal shape in plan at roof level, with V columns transferring the loads down to concrete bases at four corners. The inward slope of these columns allows them to accept horizontal loads. The tubular sections of the frame pass through the timber construction and are connected by lugs in such a way that the uplift forces from the roof are transferred into the frame. This connection of timber and steel is ­located at the zero-moment lines of the dome,

129

­Aberlour (GB

i.e. near where the compression-loaded parts of the roof – the dome – transition into the tension-­ loaded areas (Fig. D). ­Because of the geometric constraints and in order to achieve consistent ­detailing, the positions of the actual connections were ­varied slightly from the theoretical zero-­ moment lines. The V columns of the steel structure transmit the roof load into the rigid concrete supports at the longitudinal sides of the basement and from there into the floor slab of the trough-like foundation. Concrete channels under the baseplates carry the horizontal component of the thrust from the domes. The structural separation of concrete and timber construction is expressed at the western roof edge. Here the roof extends over the aisle as an exposed grillage and is supported on a sliding bearing at the retaining wall without transferring any horizontal forces between the two components. This enabled the extensive earthworks to begin before the roof had been fully designed.

E

4500

18000

18000

18000

4500 4500

18000

18000

4500 4500

18000

4500 4500

18000

18000

4500 4500

18000 4500 9000 6000 3000 3000

3000 10500 13500 18000

45

18000

°

3000 18000 3000

15 5 15 5

GSA version 8.7 Copyright © Oasys 1985-2017 GSA version 8.7 Copyright © Oasys 1985-2017

The Macallan Distillery 229222 Roof Model DL of steelwork added as gravity case 30/10/2015. File: 151030_Roof_Wiehag_Model8.gwb

The Macallan Distillery 229222 Roof Model DL of steelwork added as gravity case 30/10/2015. File: 151030_Roof_Wiehag_Model8.gwb

Part is excluded by volume

F

G

Scale: 1:102.4 Isometric Scale: 1:125.4

Part is excluded by volume

Moment, Myy: 250.0 kNm/pic.cm 344.4 kNm

Scale: 1:102.4 Isometric Scale: 1:125.4

264.1 kNm

Shear Force, Fz: 125.0 kN/pic.cm 58.38 kN

183.9 kNm 103.6 kNm

26.60 kN -5.182 kN

23.37 kNm

-36.96 kN

-56.88 kNm -137.1 kNm

-68.74 kN

-217.4 kNm

-100.5 kN

Case: L2 : Superimposed dead load roof Case: A2 : Superimposed dead load roof Contour case

-132.3 kN -164.1 kN Case: L2 : Superimposed dead load roof Case: A2 : Superimposed dead load roof Contour case

z y

x z y

x

Program GSA Version 8.7 Copyright © Oasys 1985-2017 J:\200000\229000\229222-00 Macallan Distillery\4 In...\151030_Roof_Wiehag_Model8.gwb

Printed

11-Sep-2018

Page Time

1 16:14

Program GSA Version 8.7 Copyright © Oasys 1985-2017 J:\200000\229000\229222-00 Macallan Distillery\4 In...\151030_Roof_Wiehag_Model8.gwb

Printed

11-Sep-2018

Page 1 Time 16:15

H 56

,2°

20

0 15

0 15

45

°

20

15 5 15 5

630

0 74

cc

76

c

350

c

E steel and timber ­construction grid scale 1:1,500 F section forces diagram: bending moment

130

G section forces diagram: shear force H detailed section of ­column base scale 1:20

 Base plates welded onto the bottoms of the columns are attached to the concrete below by cast-in bolts to create rigid supports. The steel tubes are bolted to one

another through circular end plates with welded stiffeners to create an almost flush-finished connection capable of transmitting bending moments.

I sequential stages of construction, construction has just started on the third dome from the left (with temporary columns)

56

,2°

The ­Macallan Distillery 0

20

CONSTRUCTION SEQUENCE Because the domes are structurally independent of one another, each section could be constructed sequentially from north to south. The parametric building model created by the timber construction contractor not only served to clarify countless details but also helped in planning the construction sequence and the ­hierarchy of the load-bearing elements: within each of the five steel frames, two pairs of orthogonally crossing main beams span 27 m (shown dark blue in Fig. C and D). Steel nodes at the four intersection points divide each beam into three and were supported on temporary timber

columns during the installation phase (Fig. I, third dome from the left and Fig. L). Then the roof ­surfaces were successively constructed using secondary beams with spans of 12, 6 and 3 m. At the stage of the digital model, each of the approximately 1,800 different timber beams were given an individual identification number, which they retain for the whole of the production and installation process. This allowed the fabricator to model and test the proposed erection methodology, plan in detail the lifting strategy for all the elements and produce the parts in the order in which they were required on site.

TIMBER CONSTRUCTION The completed grid shell displays an uncluttered underside of uniformly shaped beams 750 mm deep and 200 mm wide, which carry diagonally butt-jointed triangular roof panels. Because large shear forces occur in some ­areas of the timber construction, two different strategies were necessary for the detailing. While the majority of the panels rested directly on the grid shell, the beams in some parts of the roof had to be 200 mm deeper in the high shear areas. In these special areas, the beams extend up to the upper shell of the panels (shown in Fig. I, central dome). This also had the advantage of making all the beams look to have the same depth. There, where the increased structural depth is not achieved, the inner construction of the beams is modified: in the normal case, they

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consist of a CLT core with laminated LVL cheeks. In particularly highly loaded areas, for example at the primary beam intersection points, they have a hollow rectangular section on its side as a core. Composite action between steel and wood is achieved with screwed steel nodes. These are visible during installation (Fig. L) and are only later concealed by the cheeks. The faceted appearance remains expressed in a network of aluminium channels even after the green roof has been installed. The channels drain the roof, provide a route for services and act as a mechanical restraint for the green roof. The triangular ventilation openings are connected into this network. The panels are insulated not primarily for the usual heat loss purposes but to ensure that the green roof planting is not damaged by the heat from the stills.

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The ­Macallan Distillery

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Structural engineers Arup, Hong Kong (CN) / Manila (PH)

1811

Architects Integrated Design Associates (IDA), Hong Kong (CN)

28,8 720 480

Mactan Airport Terminal 2

30 112

49 30

520

605 134

755

4

16

71,2 150 120

36 pc. TX SK VG 10x400

40 Stift Ø70 Unterlegscheibe a = 100

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605 135

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site plan scale 1:20,000 section floor plan departures scale 1:2,500

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1 elevated walkway to ­drop-off, pick-up 2 check-in 3 passport control / security 4 shopping 5 lounge areas /gates

Mactan Airport Terminal 2

5

a

The second-largest airport in the Philippines with its characteristic design of structural timber arches is located on Mactan, one of the larger islands adjacent to Cebu. The new Terminal 2 is the gateway to the flourishing tourist destinations in the south of the Visayas region. It handles up to 4 million passengers per year and the modular layout allows for successive extensions over the next 10 years to provide up to twice the capacity. The building is a three-storey structure: the apron level and Arrivals area form the unassuming plinth to the building, while a series of barrel roofs arch over the Departures area. Their steeply sloping geometry references the traditional roof styles of the region. Three long barrels over the main areas for check-in, security and shopping create the largely column-free core of the building, shorter roofs continue the structure up to the gates. A shallower roof arch extends over the southern pier in the direction of the apron; on the other side, an elevated walkway with a foil roof connects the building to the pick-up and drop-off areas. The decision to construct the roof in timber was made in the course of the planning process and is intended to offer passengers a r­ esort-like, friendly atmosphere. The glued laminated timbers together with the natural wood and rattan of the interior fittings set an almost homely accent, an unusual look for such a modern airport. The soft, evenly distributed light from central skylights also contributes to this effect. The aluminium tube shading elements protect from the sun almost ­vertically above. The back faces of the barrels are completely glazed and set back behind the edge of the roof to protect from solar ­radiation.  Burkhard Franke

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Mactan (PH)

Text Jessica Pawlowski

A

B

C

A axonometric of the whole roof construction. The red axes mark the seismic joints.

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B  structural idealisation of the longitudinal ­stiffening

C  axonometric of the three axes of the arch structure with the ­stiffening elements

Mactan Airport Terminal 2

STRUCTURAL ELEMENTS Steep timber arches on the underside of an ­undulating roof define the appearance of the new terminal at Mactan airport. A two-storey ­reinforced concrete frame with a column grid of 15 × 13.5 m forms the base to the building. Upon this rests the Departures level with barrel roofs consisting of a series of 15 m rise, 30 m span arches. Two design options were explored in ­parallel during the planning process: a purely timber and a timber-clad steel structure. Only after the technical and economic feasibility of

the timber concept had been confirmed was it decided to adopt this option, which would be simpler and quicker to build. The timber half-arches were prefabricated in Austria, then shipped to site and erected in only three months. The two 23 m long halves of the threehinged arches consist of glued laminated timber (GLT) with a cross section of 127 × 28 cm. The arches are connected to one another by four 64 × 28 cm purlins (Fig. E). On top of these, a system of rafters supports the roof skin. Steel pin joints form the base and crown bearings.

STIFFENING The two lower rows of purlins are connected by diagonals and together form a continuous brac­ing “truss” over the whole length of the barrel. They stiffen the building in the longitudinal direction. The diagonals in each third bay of the barrel continue to the top purlin to provide in-plane stability (Fig. B and C). So that the use of the whole space is not limited by structural elements, the stiffening trusses do not extend down to the floor, but are terminated at a height of 6.50 m. Bending moments are therefore generated in the arches below this level. For this reason, the glued lami-

nated timber arches are reinforced with an 18 cm thick layer of timber on both sides. Two further layers, each 10 cm thick, would not normally have been required for structural reasons: in this case, they increase the residual cross ­section of the members in the event of a fire to achieve a fire resistance period of 120 minutes. The arch timbers, now increased to 80 cm thick in this region, rest on two parallel pin ­bearings. The pin bearings are aligned with the inner reinforcement plate bolted onto the timber, so that the forces can be transferred directly straight into the base support of the arch (Fig. F).

WIND AND EARTHQUAKE LOADS The considerable forces of nature at times in the region place special demands on the load­ bearing structure: during the typhoon season, wind speeds up to 200 km/h can ­occur, exerting positive pressures of up to 3.2 kPa and suction effects of 2.0 kPa. Even more serious is the ­location of the airport in one of the most seismically active regions on the planet. Various measures ensure the building’s earthquake resistance: the building is divided into five structurally independent sections (Fig. A). Seismic gaps ranging from 250 mm at the Arrivals level up to 550 mm at roof gutter l­evel ensure that the sections cannot impact one another during a seismic event. The reinforced concrete frame of the lower storeys is specially detailed for the flexural response of girders and columns to

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cope with the movements imposed by seismic events. Designing lightweight voided slabs ­reduced the weight of the building, in turn ­reducing the seismic ­induced forces. In the overall structural system, over strength is imposed to control the hierarchy of failure through targeting preferred yielding mechanisms: the concrete moment frame will reach flexural yielding followed by the timber roof connections and finally the timber elements. Timber is characterised by brittle failure; therefore, the philosophy is to ensure that the timber elements are the last to “fail” or yield. Seismic design requires specific connections within the timber structure to provide the ductility and yield before any failure of the timber itself can take place.

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0 127

100 180

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800

28,8 1811

28,8 720

ST08 7x10 pc. Tx SK VG 10x400

480

35

49 30

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Bogen GL28C (100)+180+240+180+(100)/1270

120 15 0 71,2

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30 112

36 pc. TX SK VG 10x400

40 Stift Ø70

605

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755

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Unterlegscheibe a=100

755

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Mactan Airport Terminal 2

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358 998

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43

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1173

Pfette GL28C 26/56,2 2435

Pfette GL28C 26/64,4 Diagonale GL28C 24/24 Pfette GL28C 28/64,4

92

Diagonale GL28C 24/24

43

84 64 52 61

TX GS W-BT Ø20x1200

15735 14563

43 99

(Haupt)bogen GL28C 24/127

Pfette GL28C 26/64,4

Sparren GL22H 80/120

Sparren GL22H 80/120

(Haupt)bogen GL28C 24/127 TX GS W-BT Ø20x1200

Rinne GL28C 20/76,4

Rinne GL28C 20/76,4

Bogen GL28C 80/127

Bogen GL28C 80/127

15000

141

Mactan (PH)

Diagonale GL28C 24/24 Pfette GL28C 32/64,4

15000

Architects wulf architekten, Stuttgart, (DE)

Structural engineers Boll und Partner, Stuttgart (DE)

Hall 10 at Messe Stuttgart

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location plan scale 1:25,000 floor plan scale 1:1,500

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hall 10 west entrance restaurant thoroughfare hall 9 hall 7 hall 8

HALL 10 AT MESSE STUTTGART

6

The Messe Stuttgart exhibition centre directly opposite Stuttgart Airport opened in 2007. This major project exceeded the expected v­ isitor and exhibitor numbers relatively q ­ uickly and an enlargement of the exhibition space was required. Messe Stuttgart’s new Hall 10 opened its doors at the beginning of 2018. In their competition design from 2000, the a ­ rchitects, Wulf Architekten, had planned for five halls to the north and south respectively. The hall at the western entrance to the site was not built in 2007 and the entrance itself was designed to be temporary. With the construction of Hall 10, the exhibition centre is complete. The long absent “fifth finger” exhibition hall was added to the south, while the entrance, which lines up with the main ­thoroughfare as does the entrance at the east – was upgraded. The challenge for the designers was to come up with a solution that would engage with the roof form, rhythm and scale of the existing halls, despite it having quite different dimensions to the standard halls (10,500 m2) or the Grand Hall (20,900 m2 plus 5,900 m2 gallery). Wulf Architekten designed a three-nave hall with a floor plan of 165 × 100 m and approximately 14,500 m2 of exhibition space. The visitors’ eyes are immediately drawn to the downward curving, largely timber roof. A steel structure comprising gerberettes and columns carries the roofs of the two side naves and the central nave. The latter rests on a total of 47 glued laminated timber beams, 68 m long and with a span of approximately 50 m, which were each delivered to site in three pieces, lifted into place by crane and the pieces connected together. Two inclined bands of skylights span the vertically stepped transition between the central and side nave roofs to ensure natural lighting. A special blind system allows the hall to be ­fully blacked out if necessary. Approximately 1,650 spotlights and lamps are fixed ­under the roof. Heike Kappelt

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stuttgart (DE)

Text

Frank Zimmermann

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A structural system scale 1:1,000 B cross section scale 1:1,000

146

C roof structure erection sequence 1– 5 sections scale 1:1,500 1 the steel structure is erected with the ger-

berettes fabricated so that the ends of the cantilevers are too high. 2 cantilever ends pulled down by a calculated amount

HALL 10 AT MESSE STUTTGART

by tensioned ropes anchored to ballast weights. 3 central piece lifted into place: the tension in the ropes reduces substantially

to a residual value, enough for the beam end pieces. 4 central piece is extended with the side beam end pieces. The tension

in the ropes is reduced to almost zero. 5 residual tension released, tensioning rope and ballast removed

Although, at first glance, the new Hall 10 ­resembles its neighbours. Firstly, the client wanted to create a space with a different ­atmosphere, and secondly, the hall is much wider than the others. In addition, there were economic aspects to be taken into account. Three substructures define the roof of Hall 10: two mirrored, 17.5 m wide side naves constructed in steel and a 68-m wide central nave in timber supported off them. The two side naves consist of single span beams spanning 17.5 m at a spacing of 6.75 m, which e ­ xtend ­towards the middle of the hall with upward-­ angled cantilevers projecting 8 m in the plan projection. Their structural form is that of a ­gerberette, an arrangement whereby the bearing force on the facade is never in tension, but remains in compression in all load cases. The green roof construction on the side naves makes a particular contribution to achieving this loading condition. It weighs about three times the weight per unit area of the foil roof over the main nave. The need to avoid tensile loads on the facade columns was because they have an F 30 coating, which does not have approval for use on tension members.

The cross section of the gerberettes varies in height and width to suit the bending moment envelopes. A 508-mm diameter circular hollow section beam running longitudinally rests on the gerberette cantilever heads and picks up the loads from the timber roof. A column is positioned along the longitudinal facades at every side nave cross-beam. A 1.6-m constant depth beam on each side provides the inner support to the gerberettes and hence carries the loads from half of the combined roof structures. Similar to the existing halls, the supports to this beam follow the rhythm of the hall doors and circulation routes. It spans alternately 27 m and 6.75 m. The central nave has 32 cm wide glued laminated timber roof beams strength class BS GL 32c spanning 49.3 m. Their depth at mid-span is 2.2 m, at the bearings 1.4 m and at the ends only 30 cm. The beams, which have a total length of 67 m, are curved downwards and thus reference the suspended roof shape of the existing halls. The 3.375-m spacing of the glued laminated timber beams halves the grid of the side nave steelwork.

THREE-PART TIMBER BEAMS There were not many valid options for manufacturing the 68 m long beams in one piece. Whether or not this would have been technically or contractually possible, beams of this length would not have been transportable; the rise in the middle was more than 7 m. The main roof beams were therefore manufactured in three parts and assembled on site: the middle piece is 49.3 m and the two beam end pieces are each 9.35 m long. The facade over the side naves is steeper than the cantilevers of the gerberettes. The facade posts also support the main beam end pieces. Fixtures suspended by steel ropes, known as bridles, which allow organisers and exhibitors to suspend their equipment from

147

stuttgart (DE)

the roof, create horizontal force components of up to 500 kg per suspension point on the beam soffit (at up to 10 points per beam). The cables are connected to robust suspension points in the webs of the T sections, which are bolted into 12-cm wide grooves in the beam soffit. Eight steel purlins bolted to the beam in the plane of the trapezoidal sheet roof cladding restrain the beams against overturning. The tops of the beams are additionally restrained by the trapezoidal sheet roof (T160-1.0). The trape­ zoidal sheet profile depth was determined not only on structural grounds but also to accommodate the building technical services ducts. A thicker version (1.50 mm) supports the extensive green roofs over the side naves.

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D  gerberette on main transfer beams and columns, facade posts with main beam end pieces and butt joint with main roof beam scale 1:250

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E  gerberette tubular beam connection showing the timber beam support plate and roof beam butt joint scale 1:50

F, G connection of the ­gerberettes to the main transfer beam, concealed frame stiffeners of the gerberette and bottom of the facade post

F vertical section scale 1:50

G horizontal section scale 1:50

HSW-E 160 x 1.0

Hall 10 at Messe Stuttgart HSW-E 160 x 1.0

HIERARCHICAL STIFFENING The timber central hall is stiffened by the steelwork. The diaphragm action of the timber roof is ensured by cross bracing in the middle and the partial diaphragm effect of the cladding. In the longitudinal direction, the horizontal loads from the longitudinal tubes are transferred via the gerberette cantilevers into the side naves. The gerberette cantilever bays are also braced with diagonals over the hall doors and the forces in them are transferred to the longitudinal transfer beam. The beam rests on the reinforced con-

crete structures at the ends of the hall. The southern end resists horizontal forces; the northern end allows l­ongitudinal movement. Horizontal bracing at the edge structure would have been too long. The inner columns are therefore built into socketed foundations, diag­ onal bracing in the roof plane of all the side naves bays transfers the horizontal loads. The two side naves are connected to the timber middle nave by non-sliding bearings at the ­gerberette heads.

PURISTIC DESIGN The appearance created by the gerberettes, longitudinal transfer beams and the timber roof is part of the architecture and emphasised by the design of the connections. The design of the structure had to be compatible with the erection concept. Web stiffeners, end plates and similar elements were generally not used and the number of visible bolts was kept to a minimum. The main transfer beam is butt jointed by pinned connections at the zero moment points in the long spans. The gerberettes are supported with a cleated joint at the main transfer beam. The cantilever moments are transferred via a concealed bolted splice plate on the top and a contact bearing compression splice at the bottom. The gerberette frame ­corners have no visible stiffeners. The webs of the two gerberette parts are joined before the frame corner and the haunch in the beam in plan extends towards the edges of the flanges

149

stuttgart (DE)

(Fig. G). A traditional frame corner stiffener ­dissecting the intersection angle is hidden in the void behind the haunch plate. The loading on the gerberette always causes a horizontal deflection component at its top end because of the geometry. The installation of the timber beam with a non-sliding connection at both ends requires the steelwork to be pre-deflected. Tensioned cables connected to ballast weights on the ground pulled the cantilever heads into the right position (Fig. C). Placing the timber beams then reduced the pretension but caused no further deflection. The very strong Lias flint clay allowed spread foundations. Although the socketed foundations of the inner hall columns were really deep at 1.50 m, they did not go down to the flint clay. They were anchored into the ground with an additional 4.6-m deep layer of lean concrete fill.

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7749

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Multi-Storey Buildings

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HALL 10 AT MESSE STUTTGART

RESIDENTIAL TOWER IN HEILBRONN

152

CONFERENCE HALL IN GENEVA

162

THEATRE NEAR BOULOGNE-SUR-MER

172

INTERNATIONAL HOUSE IN SYDNEY

180

TIMBER OFFICE HIGH-RISE IN RISCH-ROTKREUZ

190

TIMBER HIGH-RISE IN BRUMUNDDAL

198

SCHöNBUCH TOWER NEAR STUTTGART

208

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STUTTGART (DE)

Architects Kaden+Lager, Berlin (DE)

Structural engineers bauart, Berlin (DE)

Residential Tower in Heilbronn 7

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8 apartment 9 bathroom assembled entirely off site

floor plans sections scale 1:1,000

1 arcade 2 building foyer 3 communal kitchen with laundrette 4 bicycle store 5 refuse space 6 cafe 7 kitchen

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Residential tower

site plan scale 1:5,000

With an overall height of 34 m, the ten-storey Skaio is at present the tallest timber-built residential tower in Germany. Strictly speaking, the load-bearing structure consists of a large amount of timber, some concrete and only a few steel beams and columns. Directly adjoining a six-storey peripheral block development, this corner tower marks the end of the Neckarbogen district, the first section of which was completed for the opening of the National Garden Show (BUGA) 2019 in Heilbronn. Loggias and the communal roof terrace serve as extensions to the 60 compact rented apartments and rooms. A ground floor cafe forms a social meeting point for the neighbourhood. The concept of sustainability is supported by the use of large quantities of renewable raw materials. The plinth storey and access core are in reinforced concrete, which not only ­simplified the fire protection, sound insulation and bracing in comparison to a purely timber form of construction; it also ensured economic viability. The bathroom units, with 6-cm w ­ ood-based sandwich walls, were installed in their entirety by crane on the load-bearing cross-laminated floor slabs. Integrated in the external walls are 40 × 40-cm laminated ­timber columns, between which non-load bearing timber-frame elements ensure a highly insulated external skin. A surprising feature of the apartments internally are the large areas of wood that remain visible. This was made possible by a sprinkler s­ ystem, which allowed the requisite fire resistance to be reduced to 30 minutes.

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Heilbronn (DE)

The windows extending down to the floor and the loggias are partially offset from storey to storey. Since timber lintels would have led to deformation, continuous steel sections were incorporated, concealed in the facade and running round the building. They connect the heads of the columns on each floor, which are situated above each other, and they create a means of transmitting loads without deformation. The lower flange of these heavy 300-mm deep G sections serves as a linear bearing plate for the floor slabs; the upper flange supports the frame e ­ lements. Steel girders flush with the floors also link these peripheral tie beams with the core structure. Steel as a material is v­ isible only on the ground floor, however, where slender composite columns form a 7-metre high arcade in front of the cafe and the entrance zone. The 4-mm warm-grey sheet-aluminium facade cladding e ­ choes the material qualities of the composite aluminium-and-­wood windows: light in weight, it requires little maintenance, is fireproof and has a matt or gleaming metallic appearance, depending on the angle of the sun. It also lends the building a sense of precision and angularity, especiatly on the loggias. The transition from inside to outside is free of barriers. Only in the soffits over the loggias and the arcade is timber visible externally. Frank Kaltenbach

156

Residential tower

157

Heilbronn (DE)

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A At the tops and bottoms of the timber columns, steel plates form connections to the steel beams.

B The ends of the cross-laminated timber floor slabs are rebated to form bearings that fit on the steel beams.

C Non-load bearing ­external wall elements in timber-frame construction were pre-fabricated off site.

D The external wall panels are set between the load-bearing timber ­col-umns on steel beams.

E The steel beams are ­concealed in the outer walls at floor level and minimise deformation.

F Internally, the 300 mm deep HEM beams bear the columns and floor slabs with economical spans.

158

Residential tower

horizontal section: loggia scale 1:20

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1 4 mm smooth alum. sheeting with grey wet paint coating; alum. backing to joints 82 mm rear ventilation with vertical supporting structure

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2 base level: 400/400 mm reinforced concrete columns 3 upper storeys: 400/400 mm laminated spruce columns

4 timber-frame element: windbreak 18 mm gypsum ­plasterboard 80/280 mm timber studding with 280 mm insulation between

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Heilbronn (DE)

120 mm cross-­ laminated spruce boarding 5 20/60 mm flat steel balustrade 6 alum.-wood composite window with 119 mm integral low-E

glazing (Uw = ≤ 1.0; g = 0.35) 7 rainwater pipe from roof 8 Ø 50 mm drainage and emergency inlet from loggia 9 drainage channel

10 timber-frame element to inner face of loggia: 8 mm fibre-cement sheeting 40 mm battens ­windbreak 18 mm gypsum ­plasterboard

80/140 mm timber studding with 140 mm insulation between

section scale 1:20

  8 400/400 mm lam. spruce columns timber-­frame elements between: ­windbreak 18 mm plasterboard 80/280 timber ­studding with 280 mm insulation between 120 mm cross-­ laminated spruce boarding   9 base level: 400/400 mm reinf. conc. walls 10 40 mm concrete slabs on thin mortar point bedding

1 40 mm concrete slabs 16 – 32 mm layer of drainage gravel two-layer bituminous seal 380 mm non-­ combustible foam glass insulation, vapour barrier 260 mm cross-­ laminated wood roof 2 15 mm fire-resisting plate 3 steel HEM G girder 300 mm deep

4 20/60 mm flat steel balustrade 5 alum.-wood composite window with 11.9 mm integral low-E glazing 6 4 mm smooth alum. sheeting with grey wet-paint coating and alum. backing to joints 82 mm rear ventilation with vertical ­supporting con­ struction 7 perforated sheet-steel fire stop between floors

160

Residential tower

drainage layer two-layer bituminous seal 120 mm polyurethane insulation to falls 5 mm back-up seal 240 mm cross-­ laminated spruce ­boarding; airtight sealing layer 40 mm mineral fibre 19 mm three-layer fire-­resisting slab 11 5 mm linoleum, 25 mm dry screed 30 mm panel heating 30 mm honeycomb filling

20 mm impact-sound insulation; 40 mm wood-fibre insulation 10 mm g ­ ypsum fibreboard fire protection smokeproof 30 mm layer for sprinkler and lighting runs 240 mm cross-laminated timber floor 12 steel bracket for timber floor with 6 mm soundinsulating strip 13 smokeproof strip: mineral wood or three-layer fireproof sheet

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Heilbronn (DE)

13

Architects Behnisch Architekten, Stuttgart (DE)

Structural engineers schlaich bergermann partner, Stuttgart (DE) T-Ingénierie, Geneva (CH) Charpente Concept, Geneva (CH) SJB Kempter Fitze AG, Herisau (CH) Hermann Blumer, Herisau (CH) Ducret-Orges, Orges (CH)

2

Conference Hall in Geneva 3

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section, floor plans scale 1:1,250

164

1 plaza 2 foyer 3 cloakroom 4 entrance to conference hall 5 existing foyer 6 meeting area

7 void 8 conference hall 9 lounge

Conference Hall

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The new conference hall for the World Intellectual Property Organization (WIPO) is ­located near the headquarters of the United Nations in Geneva. It also serves as connector between the curved high rise slab of the WIPO headquarters and the administrative building by Behnisch Architekten. Mostly closed facades, covered in larch shingles, as well as three cantilevering segments with large-scale window openings comprise this sculpture-like building. It reveals itself fully to visitors who walk around it. The inside of the building – the foyer at the ground floor and the large hall for approximately 900 delegates on the upper floor – seems like a landscape of different levels connected by ramps and staircases. Wood is used as surface material for the facades as well as the interiors. Here, its low thermal mass and the related short reaction time support conference operations during intermittent peak use. Timber is also used for the load-bearing structure with its enormous widths and cantilevers. Aside from the complex connection technology required, the ­mechanical equipment that needed to be ­integrated into the construction posed a great challenge as well. Rather than placing special ventilation ductwork within the floors, the existing voids of the box girders were used for this purpose. During the tender process, numerous changes in the design of the timber structure took place. The ­realised ­design is based on a concept that saved both costs and material and was developed by timber engineer Hermann Blumer (see interview p. 167ff.) in collaboration with contractors specialised in timber construction. This resulted in an extraordinary structure that explores the limits of current timber construction techniques. Roland Pawlitschko

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GENEVA (CH)

Interview Hermann Blumer

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A structural principle red: main support blue: dead load  /  live load green: torsion due to asymmetrical ­cantilevers

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B  structural design model with uniform areas and bar elements (design concept)

C structural design model with walls made of truss girders, sheathing on both sides (­realized  variant)

Conference Hall

DEVELOPING AN OPTIMISED TIMBER STRUCTURE ­ ince working with Shigeru Ban on numerous realised timber structures, Hermann Blumer has S become one of the most renowned timber engineers of the German-speaking world. In 2010 the timber construction consortium Bois OMPI commissioned him to design and realise the new WIPO conference hall u ­ sing methods that were as ecological as possible and by employing regionally sourced wood as well as regional contractors.

 oland Pawlitschko: After receiving R design documents from Behnisch ­Architekten and the structural engineers of schlaich bergermann partner, how did you approach this task? Hermann Blumer: Initially, one major challenge was generating a three-dimensional form based on detailed construction suggestions and two-­ dimensional pdf files. I was aware of the fact that, due to the enormous spans, we would reach the limits of what was possible with timber as a construction material. In the first revision, it also became apparent that not only the live loads and snow loads would be decisive for dimensioning, but also the dead weight of the construction. Therefore, one of the most important goals was to make the construction as light as possible. How did you reduce the structure‘s weight? The tender documents are based on a system comprised of four shell structures for floor, walls and roof. In sum, they form a giant wood tube. Since the degree of both wood and steel consumption seemed very high, I a ­ ttempted to design a structure that would weigh half as much. After a number of attempts we eventually succeeded. The highest savings in weight were possible in the areas of the external walls. Instead of two thick slabs as in the original design (ill. B), a frame (ill. C) was developed that also serves

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GENEVA (CH)

as a wall shell with glued laminated timber sheathing on both sides. Significant savings in materials were achieved by interlocking the sheathing with the flanks of the box girder (ill. J). This leads to rigid corner connections, similar to window frames. Was the prefabrication and transport of the box girders difficult for the construction firm? They actually had to solve a number of difficult problems. The up to 27 m long box girders for floor and roof were at the limit of what a truck can carry. Each of the box girders has a different shape and some feature bends (ill. I). They don’t connect to the walls orthogonally, but at an angle. There aren’t any repetitive construction components. The level of precision needed to be extremely high. The requirement was to not exceed a degree of tolerance of 1 mm. The reason is that the connections are comprised of threaded sleeves and rods that were laminated into the wood elements as well as front plates typically used in steel construction (ill. L). This special type of construction is based on a development of the timber engineering firm Ducret-Orges. Did your structural solutions impact the design in any way? Was there a need to adjust the interiors or the exterior appearance?

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The design didn’t have to be adapted at all. All changes occurred only within the components for floor, walls and roof. If the structurally ­required timber cross sections had ­become too big, steel connectors, beams and columns were used instead. The greatest loads are located along the cantilever ­towards the Place des ­Nations. Here, parts of the frame were built in steel (ill. D), such as a column with steel ribbons along both sides – similar to a suspension bridge with anchors. A further challenge in this part of the building were the torsion forces ­resulting from the i­rregularly shaped floor plan with widths ranging from 17 to 35 m. Even though this cantilever was r­ ealised as a framed tube, the corner farthest away from the support had d ­ eclined in height by about 10 cm. This was solved in a relatively simple way by cambering. When the temporary construction ­supports were removed, the deformation

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matched the calculated boundaries rather ­precisely. The steel cross bracing directly in front of the big windows was a precautionary measure in order to avoid the glazing becoming impacted by deformation. Would it have been possible to realise the ­entire building as a pure timber ­construction? The amount of wood could have been increased, for sure. There are some areas where it is ­impossible to avoid steel. With the material we have at our disposal today, such as structural beech or pressed beech, we would have been able to do more. Unfortunately we didn’t have access to that material five years ago. In the case of the WIPO conference hall, we neither had the time nor a dedicated budget. Still: being able to save one half of the originally projected material consumption and costs is something I consider a great success.

K

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sheet, metal bronze anodised 3  ¡ 70/20 mm larchwood battens 4 triple fixed glazing light transmission: 63 %

vertical section, facade scale 1:20

1 construction box girder: 100 mm CLT 650 –1,100  mm ­glulam beam 100 mm CLT 2 roofing: aluminium

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Conference Hall

g value: 0.33 – 0.42 U value: 0.6 W/m2K 5 13 mm parquet ­flooring 20 mm 3-ply board 150 mm framing 100 mm CLT

700 mm glulam beam 100 mm CLT vapour barrier 240 mm mineral wool thermal ­insulation wind barrier

wood framing roof tile, larch wood split, untreated

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Architects Andrew Todd, London (GB)

Structural engineers LM Ingénieur, Paris (FR)

Theatre near Boulogne-surMer 2

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In June 2016, a unique new building was completed in the three-hectare landscaped gardens of the Entente Cordiale Cultural Centre near the fishing port of Boulogne-sur-Mer. The round, wooden building is the first theatre in France designed on the Elizabethan model and is similar in size to London’s 1587 Rose Theatre. While the English original was notable for its multi-sided, simple, basic form in timber and an internal, open courtyard with a surrounding pitched roof, the newly opened theatre shows some unusual touches in its ­appearance: behind a circular bamboo curtain lies an ancillary composition of cylindrical spaces of differing heights. The inconspicuous entrance leads via a small foyer directly to the centrally located theatre hall. This auditorium will also host other events, such as conferences and operas.

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The stalls and two other tiers of seating can accommodate up to 388 spectators. The band of windows in profiled glass towards the top of the walls admits ample natural light. The impression of calm created in the space is mainly the result of the large areas of untreated wood surfaces in pine, spruce and larch. All above-ground ceilings and load-bearing walls are constructed from pre-finished, flat and curved cross-­ laminated timber (CLT) panels. This is the first use of curved solid wood elements in a theatre and signals, together with the building’s completely natural ventilation system, the high ecological credentials of the design. Working together with the structural engineer and an ambitious timber construction company, the planning team was able to reduce the construction time of the timber structure to about seven weeks. Amlis Botsch

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Boulogne-sur-Mer (FR)

Text Laurent Mouly, Grégoire Mouly 1

2

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4

facade section scale 1:20 1 waterproofing PVC 150 mm insulation vapour barrier 19 mm OSB sloped to falls 109 mm 5-layer cross-laminated timber 2 2× Profilit glazing in ­aluminium frames 3 laminated safety glass in aluminium frames IPE 160 steel section Wand UG oder Dämmung oder..?

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4 40/40 mm vertical larch battens 25 mm 2-layer battens membrane permeable 15 mm 2-layer ­Multiplex sarking 147/46 mm timber studs rockwool in between vapour barrier 109 mm 5-layer cross-­laminated timber

EXTRAORDINARY TIMBER STRUCTURE The load-bearing structure of the theatre building is composed of three basic materials. The whole of the timber superstructure rests on a reinforced concrete basement with a heavy, 50-cm thick floor slab, which prevents the building floating due to the local high groundwater levels. Elevated steel support beams on the ground floor carry the stage and the surrounding raised areas of the stalls. The circular walls of the superstructure in curved spruce CLT are connected by radial, straight CLT walls. This combination, with the ceiling panels, creates a highly stiff overall structure. Glued laminated timber (GLT) columns in oak support the fronts of the two upper seating tiers and form the bearing points for the underspanned GLT beams of the roof. The dynamic

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behaviour of the building under seismic loads was investigated using an analysis of the lateral force effects in accordance with E ­ urocode standards. The distribution of the horizontal loads on the whole structure was a ­ nalysed using a digital model. The timber elements were generally left untreated in all internal areas. To ensure the ­resistance of the load-bearing structure in the event of fire, the relatively low fire resistance class M3/Euroclass D of the wood was compensated for by enhancing the building’s fire safety systems, alarms, escape routes, etc. Only the soffits of the upper tiers of ­auditorium seating and the separate stairwell were treated with a glaze to raise the fire ­resistance class to M1/Euroclass B.

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A supply air inlet

B ventilation simulation

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C steel beam supports / ventilation chambers

D prefabrication in the ­workshop

E horizontal / vertical solid timber structural ­elements

F axonometric of the load-bearing structure

NATURAL VENTILATION Natural ventilation was produced through the use of two physical phenomena: the positive pressure and suction of the wind striking the building and the differences in air pressure within the building due to thermal effects. The challenge for the designers was to achieve a suitable interaction between these parameters. Changing wind conditions in this coastal location represented an important factor in the design. Fresh air flows into the building through low-level opening slots in the masonry facade plinth under the raised stalls area and stage and is introduced evenly into the theatre hall through a system of chambers. The room air is tempered directly on entry at all times of year by the thermal inertia of the building materials and by air heaters.

F

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Boulogne-sur-Mer (FR)

A control system for the air inlets and outlets specially developed for the project regulates the air change rates according to need. The ventilation system was designed by calculation augmented by digital simulations and model trials in a wind tunnel at Laboratoire Aérodynamique Eiffel in Paris. Since the theatre was brought into use, the ventilation behaviour has been studied in a research programme and the system optimised. The untreated spruce with its sensuous appeal and hydroscopic properties creates a special ­atmosphere. The absence of vibrations from mechanical ventilation systems ensures nothing disturbs the peaceful ambiance of the space and the interaction of the visitors with the architecture.

Architects Tzannes Architects, Sydney (AU)

Structural engineers L  endlease DesignMake, Eastern Creek (AU)

8825

I­ nternational House in ­Sydney

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­International Hous

The International House in Sydney is Australia’s first multistorey office block in engineered timber. It is located in the lively central business district of Barangaroo at the old Sydney Harbour – an area that, with its old quay and since demolished warehouses, has a long history of timber construction. The client had several reasons for choosing timber for the building: timber building sites are b usually dry and generate very little dust or noise. A second reason was that people in neighbouring buildings, working on the site or passing by would experience less disturbance and, if they did, it would be for shorter periods. Moreover, timber binds CO2 and promotes the good health and well-being of the building 5 a new type of hybrid beam made from beech users. In addition, the design for the office building involved 4 a a laminated veneer lumber (LVL) and spruce glued laminated timber3 (GLT). 3 3 Timber is used not only for the load-bearing structure but also for the 2 2 building interior. Ceiling and wall surfaces are left unclad and the lift shafts and stairwells are also constructed in timber. Timber surfaces define the atmosphere in all the interior rooms – bwith the exception of the sanitary areas. Furthermore, the material is a key component of the sustainability concept, as are the reused timber bridge beams in the columns on the ground floor, the PV modules on the roof and the LED lighting. Roland Pawlitschko

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INTERNATIONAL HOUSE

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STRUCTURAL CONCEPT Structurally, the International House Sydney consists of a single-storey concrete plinth with an intermediate floor and five office storeys above, built entirely of glued laminated and

cross-laminated timber elements. Glued ­laminated timber diagonals in all four facade planes provide the stiffening to the building.

COLUMNS OUT OF RECYCLED TIMBER The Y shaped colonnade columns on the two retail storeys are comprised of a lower concrete component and two upper Australian eucalyptus (ironbark) timber elements. The latter are 420 × 420 mm in cross section and each con-

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Sydney (AU)

sists of four recycled timber beams ­recovered from disused railway bridges in Queensland. The ­columns form a compound section in accordance with Eurocode 5 with shear ring connectors and orthogonally crossed through bolts.

A

B

A open plan office with ­unclad glued laminated timber (GLT) beams and columns and cross­ laminated timber (CLT) walls and ceilings

B hybrid beam manufactured from spruce glued laminated timber (GLT) with internal laminations of beech laminated ­veneer lumber (LVL)

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­International Hous

HYBRID BEAMS OUT OF SOFTWOOD AND HARDWOOD The limited building height and the need to route building services pipes and ducts through the beams called for an innovative ­solution for the beam construction. Working with timber suppliers Stora Enso and Hess Timber, and the Materials Testing Institute (MPA) at the University of Stuttgart, the structural engineers developed a hybrid solution out of particularly high-strength beech LVL and normal grade spruce GLT. The 480 × 800 mm beams each consist of three GLT components, between which are sandwiched two vertical bands of LVL extending over the whole height and length of the member. The structural engineers used finite element analysis to model the stress distribution in the beams, in

particular around the services penetrations. Physical tests to confirm load capacities and ­behaviour in fire were also carried out. The penetrations through the beams are much larger and the distances between them much smaller than recommended by current guidelines – e.g. DIN EN 1995-1-1-1/NA and Euro­code 5. MPA Stuttgart performed tests on sample beams to confirm the analyses and investigations during the preliminary ­design. The test r­ esults not only confirmed the accuracy of the finite element analyses but a ­ lso showed that the penetrations through the beam did not adversely affect their behaviour under load, thanks to the two LVL bands.

PREFABRICATION CLOSE TO THE SITE Because of the shortage of space on site and to reduce crane usage, the contractor decided to preassemble some of the timber components at an assembly works near the Barangaroo district and transport them as larger elements to the site. Prefabricated t­ imber components manufactured in Europe were sent directly to the

­ ssembly works in order to reduce the need a for storage on site. The timber lift cores and ­diagonally braced ­facade bays were preassembled off site and lifted into their final positions as complete e ­ lements. This optimised the use of the main crane and increased the speed of the fitting out and services installation work.

LEARNING PROCESSES DURING CONSTRUCTION Even though not one member of the installation team had any previous experience with ­prefabricated timber elements, the speed of ­installation improved from eight elements per day at the start of construction to a final rate of thirty-three elements towards the

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end. After an initial familiarisation phase, the 1,300 m2 ­storeys were being completed at a rate of one per week – including all the glued laminated timber beams and columns as well as the cross-laminated timber walls and ceilings.

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Sydney (AU)

Architects Burkard Meyer Architekten, Baden (CH)

Structural engineers MWV Bauingenieure, Baden (CH)

Timber Office High-Rise in Risch-Rotkreuz

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6 main access core 7 offices 8 roof terrace

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1 foyer 2 shopping 3 basement access 4 store 5 internal courtyard

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Timber Office High-Rise

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a

The first timber office high-rise in Switzerland was built at Suurstoffi, a former industrial area in Risch-­ Rotkreuz by the side of Lake Zug. The building, which is divided into two volumes, offset to one another and overlapping in plan, has two access cores and an inner courtyard. The design is characterised by the open, freely divisible floor plan, which allows a high flexibility of use and can be divided into rental areas of various sizes. Structurally, the building is a timber skeletal frame and was completely prefabricated except for the two in-situ concrete access cores. Beech laminated veneer lumber (LVL) was used for the solid timber columns and downstand beams in the interior of the building, while spruce glued laminated timber (GLT) was used for the less heavily loaded ­columns in the plane of the facades. The timber-concrete composite floors act with the r­ einforced concrete cores as horizontal stiffening. Integrated building ­services elements provide cooling, heating and ventilation. Installing these prefabricated components with their exposed timber surfaces and acoustic ceilings attached considerably reduced the overall construction period. In contrast to the warm wood colours of the ­internal spaces, the facade, which is made from encapsulated timber elements with a black cladding of composite aluminium boards, gives the building a reserved, elegant external appearance. Roland Pawlitschko

193

Risch-Rotkreuz (CH)

Text Fabian Dinkel

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A  concrete structure (grey), timber structure with components made from spruce (light brown) and beech veneer lumber (dark brown)

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B assembly system

C concurrent working on the concrete core and timber structure

Timber Office High-Rise

D timber-concrete ­com­posite system floors with pre-installed ­building ­services ­components

E visual effect of the exposed timber texture

At the time of the design, there was hardly any practical experience in how timber com­ ponents perform when transferring high loads, because this was the first timber high-rise to be built in Switzerland. Its construction would

not have been possible before the 2015 revised fire protection regulations, which require, among other things, sprinklers on all floors and encapsulated facade components.

DISTRIBUTION OF ROLES Timber engineering contractor Erne had a number of different duties to perform under the lead consultant, architects Burkard Meyer. Along with its subsidiaries, Erne was site ­manager for the whole building, constructed the nine-storey timber structure from ground floor to roof and was responsible for the construction of the reinforced concrete basement. Also part of Erne’s responsibilities were the two reinforced concrete stairwell access cores, which the company’s construction arm undertook as a subcontractor. This cooperative working ensured close coordination between

timber and concrete trades, which was essential to fulfil the tight schedule and take only two weeks per storey to erect the structure ready for finishings. The structural engineering design of the timber structure with prefabri­ cated columns, downstand beams and timber-­ concrete composite floor elements was done by Erne engineers because they already had strong links with production and familiarity with internal processes. The reinforced concrete design and overall stability calculations for the building were performed by consulting ­engineers MWV.

PREFABRICATED FLOOR SYSTEM An important component of this project is our patented floor system. It combines timber-­ concrete composite floor elements, which we produce in the factory with pre-installed building services: e.g. heating, cooling, ventila-

tion and sprinkler pipework. Among the ­advantages of this prefabricated system are its simplicity, which makes manufacturing and installation much easier as well as con­ siderably reducing the construction period.

STRUCTURE The floor elements are supported on pin-ended columns. The structural connection of the concrete layer to a plate at the column head and the concrete access cores provide horizontal stiffening to the building. While the columns in the plane of the facades are spruce GLT (340 × 340 mm), beech LVL is used for the columns around the two concrete cores (1st and 2nd floors: 400 × 400 mm, above this level 340 × 340 mm) and the downstand beams (340 × ­ sing hardwood 480 mm). The advantage of u here is its high compressive strength – spruce columns would have been disproportionately large. The cross section required for structural purposes was determined by the column head detail. The column head is reduced in cross ­section compared to the columns themselves in order to create a simple bearing for the down-

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Risch-Rotkreuz (CH)

stand beams. Above this, the column head ­becomes smaller again in order to provide a neat, step-free support to the spruce beams of the floor above. The prefabricated timber-concrete composite floor elements are 2.90 m wide, up to 8.30 m long and have four spruce ribs. The 8 t elements arrived on site ready to carry their loads. They were placed adjacent to one another and connected by inset welded components to form a shear connection. The joints were filled with high-strength grout so that the floors could achieve fire resistance class REI 60. This grout was also used between the columns, where a steel plate transfers the loads and a vertical pin locates the components. A film protected the timber column head from moisture in the grout.

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1 false floor installed by client, 150 mm void sub-floor with 80 mm impact sound insulation 120 mm concrete slab forming part

of the composite floor element 300 mm spruce GLT beams forming part of the composite floor ­element / integrated

Timber Office High-Rise

building ­services equipment 480 mm beech LVL downstand beam 2 340 × 340 mm beech LVL column 3 grout and locating pin

H t imber concrete com­ posite floor system with integrated building services equipment

I building services model J structural model

CONSTRUCTION SEQUENCE Instead of constructing the concrete core first and then the timber structure, we completed them both in parallel. This simplified the details and speeded up the erection sequence. For ­example, transverse forces were transferred into the concrete cores simply by the spruce ribs

being supported on neoprene bearings placed in machined-out pockets. At the same time, we connected the reinforcement projecting from the floor elements with that of the concrete core and cast them in one concrete operation into a monolithic unit.

FUTURE APPLICATION The structural concept used here could also be aopted for much taller buildings. We are ­currently building another timber ­high-rise

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Risch-Rotkreuz (CH)

nearby. It uses the same floor system but has 16 storeys and reaches a height of 60 m.

Architects Voll Arkitekter, Trondheim (NO)

Structural engineers Sweco, Lillehammer (NO)

Timber High-Rise in Brumunddal

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In Brumunddal, around 140 km north of Oslo, stands the world’s tallest building to be constructed with load-bearing components made completely from timber. The 85.4 m high Mjøstårnet takes its name from the nearby Mjøsasee, Norway’s largest lake and was completed at the start of 2019. The location in a popular holiday area directly on the main road between Oslo and Trondheim was the spur for the local investor to realise an ambitious mixed-use project of this size in a town with only 10,000 inhabitants. The 18 storeys of the tower provide around 11,300 m2 net floor a ­ rea. Above the entrance storey with its lobby, reception and restaurant are building services and conference floors, five office storeys and a four-storey hotel with 72 rooms. Thirty-three residential units with balconies overlooking the lake are on floors 11–15. The top two floors are divided into three further residential units, an exhibition room and a public viewing terrace. The new build complex is complemented by a public swimming pool in one of the low-rise buildings adjacent to the tower. The speed of construction of timber structures was fully exploited at Mjøstårnet: only 15 months separated the ground-breaking and topping-out ceremonies, and the whole construction took barely two years. Unlike many other timber buildings, Mjøstårnet also displays the material from which it has been constructed to the outside world. The facades consist of large, prefabricated elements with fireprotection impregnated timber cladding. A glued laminated timber (glulam) pergola bolted to the top storey ceiling slab acts as an eye-catching crown to the tower. Jakob Schoof

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­Brumunddal (NO

Text Rune Abrahamsen

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2 4 3 5 1

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16,70

A The building was erected in 4–5 storey segments. Columns and beams were preassembled on site into ladder frames for each segment.

B  axonometric of the ­structure

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Timber High-Rise

1 1485/625 mm glulam ­corner columns 2 725/810 mm and 625/630 mm glulam ­intermediate columns 3 625/990 mm glulam ­diagonals

4 downstand beams below concrete floor slabs: 625/585 mm and 625/720 mm glulam 5 downstand beams below timber floors:

395/585 mm and 395/675 mm glulam 6 cross-laminated timber lift shaft

The main load-bearing system of Mjøstårnet consists of internal glulam columns and beams as well as large-scale glulam trusses along the facades. The trusses handle the global forces in the horizontal and vertical directions and give the building its necessary stiffness. Cross-laminated timber (CLT) walls are used as secondary load-bearing elements for the three lift shafts and two staircases inside the tower. However, the CLT does not contribute to the building’s horizontal stability. The building envelope consists of large, 50 – 60  m2, one-storey high facade elements ­attached to the outside of the timber structure. These sandwich-­type elements come with insu­ lation and external cladding already fixed. Just as with the internal CLT walls, the facades do not

contribute to the global stiffness of the building. In total, about 2,600 m3 of structural timber was used for Mjøstårnet. The building has a footprint of about 17 × 37 m. The huge concrete slab on the ground floor is supported by 60 m long piles, which are driven into bedrock and can handle both compression and tension forces. This was necessary in order to prevent the relatively lightweight tower from overturning during strong winds. The largest axial forces occur in the four corner columns. With a cross section of 1485 × 625 mm, each of these columns can withstand ULS maximum compression and tension loads of 11,500 and 5,500 kN respectively. Typical cross sections of internal ­columns are 725 × 810 mm and 625 × 630 mm.

CONCRETE FLOORS COUNTERACT WIND ACCELERATIONS Whereas floors 2 to 11 consist of prefabricated timber elements, floors 12 to 18 are 300 mm thick concrete made of a precast element at the bottom and an in-situ layer of topping concrete. Replacing wood with concrete on the upper floors means that the building will be heavier towards the top. Since Mjøstårnet is slender in its weak direction, the extra mass is necessary to comply with comfort criteria for wind-induced acceleration in residential build­ ings. The concrete floors also made it easier to obtain a high standard of sound protection in the apartments. Each floor acts as a diaphragm that lends s­ tiffness to the timber skeleton. Both

the timber and the concrete floors are supported by glulam beams, with typical sections up to 625 × 720 mm for the concrete floors. The largest diagonal trusses in the structure have a cross section of 625 × 990 mm. All glulam elements are connected by means of slotted-in 8-mm steel plates and 12-mm dowels. The structural timber elements are placed inside the building envelope, which protects them from rain and sun, thus increasing durability and reducing maintenance. Service class 1 according to EN 1995 applies to all timber elements except the rooftop pergola.

CHOICE OF MATERIALS Untreated Norway spruce is the main species used for structural timber in Mjøstårnet. The ­exposed timber in the pergola is made of pressure-­ impregnated Scots pine. Glulam strength classes GL30c and GL30h as per EN14 080:2013, as well as CLT with bending strength fmk = 24 MPa

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have been specified for the structural elements. The ­connecting elements in the timber structure consist of powder-coated S355 steel in combination with acid-proof steel dowels. The wooden cladding is fire impregnated by the manufacturer and thus has fire-retardant properties.

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D steel column base with a connection to a diagonal and anchor bolts in the foundation elevations  scale 1:50

E  column-beam connection with gusset plates showing gaps sealed with intumescent fire strips (dark grey)

HOLLOW-BOX FLOOR ELEMENTS FOR LARGE SPANS The maximum floor span in Mjøstårnet is 7.5 m. The floor elements consist of a hollow-box deck system made of glulam and laminated veneer lumber, with the cavities inside the elements filled with mineral wool. Most elements have a 50 mm concrete screed on top. The floor ele-

ments use less timber than solid CLT decks. ­Moreover, they are light and quick to assemble, and meet both acoustic and fire requirements. Floor spans of almost 10 m can be achieved with this technology, which increases architectural flexibility compared to other timber-based floors.

UP TO 120 MINUTES OF FIRE RESISTANCE The fire strategy report for the project states that the main load-bearing system must withstand 120 minutes of fire. Secondary load-­ bearing elements such as floors must have a fire resistance of 90 minutes. According to Eurocode 5, the fire resistance can be obtained by calculating the remaining cross section after charring. Furthermore, the fire design is backed up by burnout tests, which proved that the large glulam columns will self-extinguish and prevent a building collapse. The structural timber elements inside the building can thus remain visible, with no need for fireproof cladding. Visible wood in escape routes as well as in the main staircase and lift shafts has been coated with fire-retardant paint. Only the CLT walls in the escape stair­

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case had to be covered with plasterboard. To further enhance fire protection in Mjøstårnet, a sprinkler system has been fitted throughout the building. Fire barriers in the facades prevent fire from spreading vertically from one floor to another. Connecting steel plates and dowels are embedded more than 85 mm deep into the timber. Gaps and slots between beams, ­columns and plates have been fitted with intumescent fire strips (Fig. E). This material expands to about 20 times its volume when the temperature reaches 150 °C. When it comes to robustness, the structure is designed to ­sustain the loss of the horizontal stiffness of one timber floor. It can also carry the impact load of a timber deck falling onto the floor below.

LOADING AND DYNAMIC DESIGN Wind turned out to be the dominating load in the design combinations. The wind load is applied as a static load. Wind tunnel tests were found to be unnecessary because of the regular geometry of the structure. A maximum horizontal deflection at the top of the building of 140 mm has been calcu­ lated, which is very little for a building of this height. However, dynamic accelerations are ­crit-­ical for timber high-rises. Mjøstårnet is a tall building with a low structural weight. Its first nat-­ural frequency is 0.37 Hz, and thus in a range where wind can cause annoying motion or nausea. The stiffness and mass of glulam

and concrete are well known. Based on calcu­ lations and measurements done at a previous timber high-rise in Bergen, it was possible to predict the structural damping of a glulam truss system quite well. A basic wind speed of 22 m/s and a structural damping ratio of 1.9 % were used for Mjøstårnet. Analyses with an FEM model of the building showed that the peak ­accelerations due to wind on floor 17 are on the limit of what is acceptable for residential buildings as per ISO 10 137 and slightly above the limit on floor 18 (Fig. F). The client has ­accepted that potential buyers of the penthouse apartment will be informed about this fact.

EXTENDING THE HEIGHT OF THE BUILDING When the project was initiated, the height to the architectural top was set to be 81 m, and all structural analyses were performed based on this assumption. Well into the design process, and after the foundations were built, the client instructed the design team to make the building as high as possible and build the pergola with larger glulam sections that give an impression of the load-bearing structure inside the building.

This proved to be a huge challenge. Sweco’s ­engineers came up with the idea of using timber sections with rounded edges for the ­pergola. This reduces the wind load and made it possible to stretch the top of the building to 85.4 m. It also meant that about 1 km of large glulam sections had to be rounded with a radius of 140 mm on all edges. This was done at a ­flagpole factory in the south of Norway.

ASSEMBLY WITH MINIMAL TOLERANCES For the installation, Moelven employed a new and untested assembly technique. In previous projects, large or complicated trusses were first assembled at the factory in Moelv before being transported to the building site for final assembly. In this case, the individual members were transported directly to the building site, without any form of trial assembly. The beams

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arrive fully processed and must fit down to a millimetre. This construction method ensures a quicker production process and made it ­possible to build Mjøstårnet faster and at a lower cost. In the end, only one out of ­several hundred large glulam elements produced for the building did not fit and had to be replaced by a new one.

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Architects & structural engineers schlaich bergermann partner, Stuttgart (DE)

Schönbuch Tower near Stuttgart 9

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Schönbuch Tower

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Schönbuch Nature Park to the south of Stuttgart has been one tourist attraction richer since summer 8 8 8an elegant, 35-m tall viewing tower. 2018. On the top of Stellberg Hill at 580 m above sea level stands Visitors can enjoy an open 360° panoramic view over the Black Forest. The tower consists of eight 10-m long masts made from larch glued laminated timber. The masts 1010 10 fan out upwards and carry three viewing platforms at heights of 10, 20 and 30 m above the ground. A double helix in the form of two steel staircases with cantilevering steps winds around the masts. The client wanted an open structure that harmoniously connects with the surrounding forest. Structurally, the tower is unusual in that it is a combination of timber and steel, which, according to the designer “work superbly together” on this project. The heartwood for the masts9 9comes from larch trees grown in this 9 region. The careful choice of material and processing, along with the ability to have individual segments 1010 10 of mast r­ eplaced at a later date, make this structure maintenance friendly and sustainable over a long 1111 11 0 0 0 service life. The tension forces arising from prestressing are transmitted by an external, double-curvature steel cable net into the anchor foundations at ground level. The net also resists2,002,00 the 2,00 lateral forces arising 11,30 11,30 11,30 from wind, which is a common weather feature in this range of hills. The Stellberg is a former landfill site and s­ olid waste tip. The possible presence of contaminated soil ruled out a deep foundation s­ olution, so the engineers decided on spread foundations. Because of poor ground conditions and the risk of settlement, the structure had to be light in weight so that it applied no additional load to the landfill material.  Heike Kappelt

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1 2 Ø 24 mm spiral cables 2 Ø 31 mm spiral cable 3 8 I-section steel masts, timber fillers

4 8 timber masts, 500/450 mm (up to platform 3) 5 steel platform 6 Ø 28 mm spiral cable ­(primary cable net)

Schönbuch Tower

7 spiral stairs with cable net handrail 8 cable net handrail clamped to primary cable net 9 Ø 2000 mm mast bases

10 cable net connection with turnbuckle 11 mast foundation, ring foundation and tie beams

STRUCTURAL CONCEPT The Schönbuch Tower is a widely visible, minimalist structure designed and implemented to satisfy the client’s wish from the beginning for a sustainable concept. The structure consists of eight timber masts with a 45 × 50 cm cross section arranged in a circle and divided into four segments vertically. They are stayed outwards by steel cables. The masts and cables carry three circular steel platforms, two approximately 9 m and one 12 m in diameter. Under each platform is a ring beam with a welded steel box section. Two staircases, one ascending and one descending, are attached only to the masts, which stand on a 2 m diameter foundation projecting above ground level. This mast

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Ø 31 mm spiral cable Ø 328 mm spiral cable cable clamp cable net handrail clamped to stay cables

STUTTGART (DE)

5 outer edge beam, platforms 1/2/3 6 outer radial beams 7 chequer plate, platform ribs, platforms 1/2/3

foundation sits inside a 13 m diameter reinforced concrete ring to which the stay cables are anchored. Reinforced concrete beams connect the two foundations to avoid high ground pressures in the area of the mast base, which would otherwise result from the cable prestressing force (5,000 kN). To counteract settlement of the subsoil of this former landfill and solid waste tip, soil was excavated in some areas and replaced with foam-glass fill. The 1,000 t mass of the excavated material equals that of the tower, foundation and backfill. In the event of the tower starting to lean, it can be corrected by adjusting the turnbuckles at the base of the cables.

8 inner tapering beams 9 inner edge beam, platforms 2/3 10 platform ring beam b = 250 mm, h = 350 mm

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1 tapered mast top 2 machined steel block 3 steel tang with frontal radius, welded onto the head plate 4 mast ring / mast ring beam, box section

5 milled steel block with 135 slider pin and openings in the sides for 130 135 jacks to allow mast replacement 130 6 cover fixed with counter sunk screws

Schönbuch Tower 39,7 50

C connection nodes mast – platform exploded drawing  section  scale 1:10

7 steel head plate with drip edge 8 2 slotted stainless steel plates fixed with 12 Ø 16 mm dowels 9 timber mast

10 pin for mast replacement fixed with ­countersunk screws 11 timber filler piece 12 cladding plate

REPLACEABLE MAST SEGMENTS The openness and lightness specified by the client excluded any form of enclosure or roof. The designer paid particular attention to the service life of the timber masts, which would be exposed to the weather. Any kind of waterproof coating was deliberately discounted. ­Weather resistance was achieved by construc­ tional ­details. Inclined instead of horizontal timber ­surfaces and good ventilation reduce the risk of permanently moist conditions damaging the timber members. The head plates connecting the mast segments to the ring beams have drip edges (Fig. C). Concealed steel plates are integrated into the ends of the mast segments in the area of the connection to the ring beams. To significantly further increase the service life of the whole structure, the design allows individual mast segments to be replaced quickly and easily. The concept is based on a special connection (Fig. C) and flat hydraulic jacks, which can be attached to the top of the mast head plate on both sides to push the platform upwards

and relieve the load on the mast segment to be replaced. Removing the sliding pin and ­depressurising the jacks completely removes the load from the mast. It is then pivoted ­inwards and lifted out of the tower through the central opening. The ring beams are designed such that the loads from the platforms above can be shared between the two neighbouring masts. New segments are installed by following the same procedure in reverse. During erection of the tower, the diagonal c ­ ables are tensioned and move the outer edge beams of the platform down several centimetres. The position of the platform ring beam above the masts hardly changes however. To prevent the resulting imposed strains from ­affecting the structure, the outer segments of the platforms are connected by pinned joints to the ring beams. Initially, the edge beams were ­attached to the cables higher than their final position, into which they drop as a result of the vertical deflection, thus ensuring the platforms drain naturally.

DYNAMIC BEHAVIOUR The dynamic behaviour of the structure was anal­ysed based on natural frequencies. It found that visitors could induce horizontal oscillations in the frequency range between 0.6 and 1.5 Hz. The generation and amplitude of the vibrations depend on the damping of the system, which cannot be calculated accurately in advance. Based on experience, timber structures provide

higher damping than concrete or steel structures because more ­vibrational energy is dissipated by friction in the connections. If necessary, damping can be increased by installing tuned mass dampers. Based on this beneficial behaviour and the low perceivable accelerations, they were not installed during erection. They can, however, still be retrofitted to the Schönbuch Tower

ERECTION AND LIFTING INTO PLACE After delivery of the components, the site team assembled the three individual tower segments (two 10 m and one 15 m long) at ground level, stabilising them with temporary scaffolds. A 500 t mobile crane lifted the top segment – consisting of the middle and top platforms, the timber masts between them, the steel mast end segments at the top and the suspended stay cables – onto the segment below it. Then the

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middle segment with stay cables and tie rods was attached to the underside of the top segment and the then 25 m high, 100 t combined construction lifted and placed on top of the bottom segment, which was ­already in its final position. In a concluding step, the stay cables were attached to the anchor points and the prestress applied. The complete lift took only one day.

Appendix

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AUTHORS

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IMAGE CREDITS

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PROJECT PARTICIPANTS

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IMPRINT

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STUTTGART (DE)

AUTHORS RUNE ABRAHAMSEN Rune Abrahamsen is Manag­ ing Director of Moelven Limtre, Norway’s largest glued laminated timber man­ ufacturer. He studied civil engineering at the Norwe­ gian Institute for Technology and was previously Senior Vice President at Sweco consulting engineers.

TIM BUTLER Tim Butler is a civil engineer at Lendlease and was ­responsible for the design of prefabricated timber con­ struction on the International House in Sydney and many other projects worldwide.

LAURENT CLÈRE Laurent Clère is a civil ­engineer and co-founder of RAINER BARTHEL Arborescence consulting Rainer Barthel was the Chair engineers in Lyon. He was of Structural Design at the responsible for the struc­ Department of Architecture tural engineering design on at the Technical University the Sports Hall in Rillieuxla-Pape. of Munich between 1993 and 2021. He founded FABIAN DINKEL ­Barthel+Maus consulting Fabian Dinkel is a timber engineers in 1996. construction engineer ­specialising in digital building HERMANN BLUMER and has worked at Erne Hermann Blumer is a civil Holzbau since 2014. He was engineer and Management jointly responsible for the Board member of Création structural engineering Holz Herisau, Switzerland. design of the timber struc-­ He played a leading role ture for Switzerland’s first in the design of the timber timber high-rise in Rischstructure for the World ­Intellectual Property Organi- Rotkreuz. zation (WIPO) Conference Hall in Geneva. JOHANNES DUDLI Johannes Dudli is a civil OLIVER BOPP ­engineer and associate at Oliver Bopp was responsible Schnetzer Puskas Ingenieure. He was project manager for for the timber structure of the complete structure and the Heuried Sports Centre in Zurich as project engineer the timber construction of at Pirmin Jung Schweiz AG. the Sports Hall in Heuried, Zurich. AMLIS BOTSCH Amlis Botsch studied archi- PAUL EDWARDS tecture and worked under Paul Edwards is a civil Prof. Jan Knippers at the ­engineer and associate at ­Institute of Building Structu- Arup in London, where he res and Structural Design was senior engineer and (ITKE) at the University of project manager for the new Stuttgart. Between 2016 and Macallan Distillery. 2019, he was a freelance editor at Detail.

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APPENDIX

ADRIEN ESCOFFIER Adrien Escoffier has been working as a structural ­engineer for Egis since 2010. He was responsible for the geometric design and paramet-­ric modelling of the Allianz Riviera Stadium in Nice. PAUL FAST Paul Fast is the founder and managing partner of the international structural engineering consultancy Fast + Epp. Together with Derek Ratzlaff, he was ­responsible for the structural engineering design of the Grandview Heights Aquatic Centre in Surrey. BURKHARD FRANKE Burkhard Franke is a freelance architect, editor and photographer. He writes ­regular specialist articles for Detail and structure – published by Detail. ANDREAS GABRIEL After practising architecture for many years, Andreas ­Gabriel became an editor at Detail, where he was ­responsible for the conception and realisation of publications on special topics, technical books and new magazine profiles until 2018.

PIRMIN JUNG Pirmin Jung is the founder of the Pirmin Jung engineering consultancy for structural engineering design, building physics and fire protection, which was responsible for the design of Switzerland’s tallest timber-hybrid high-­ rise in Risch-Rotkreuz. FRANK KALTENBACH Frank Kaltenbach has worked as an architect for several well-known architectural consultancies at home and abroad. He has been an editor at Detail since 1998 and is a publisher, author, moderator and specialist for technical articles. HEIKE KAPPELT Heike Kappelt is a civil ­engineer. She started in 2016 as a member of the Detail project team and ­switched after almost 2 years to be an editor of structure by Detail. Since January 2020, she has been working in the Detail editorial team.

SOPHIE KARST Sophie Karst is a freelance architect and author in Munich. She worked as a lecturer at the Institute of Planning and Design at the University of Stuttgart. THORSTEN HELBIG Between 2009 and 2019, Thorsten Helbig is managing she was a freelance editor partner of knippershelbig at Detail. and played a leading role in the design of the integral ANDREAS KEIL Stuttgart Timber Bridge. Andreas Keil is a partner He is also associate profes- at schlaich bergermann sor at the Irwin S. Chanin partner. He was deeply School of Architecture, The ­involved in the conception Cooper Union, New York. of the Viewing Tower at Schönbuch Nature Park and oversaw the design and construction from the beginning to its completion.

HENNING KLATTENHOFF Henning Klattenhoff is a civil engineer and worked as team leader for Assmann Beraten + Planen, where he was responsible for the structural engineering design of the Frischeparadies in Stuttgart.

GRÉGOIRE MOULY Grégoire Mouly was responsible for the design of the natural ventilation system for the Theatre Building near Boulogne-sur-Mer.

GEORG VRACHLIOTIS Georg Vrachliotis has been Professor for Theory of ­Architecture and Digital ­Culture at the Technical University of Delft since 2020. Prior to this, he was Professor of Architectural Theory LAURENT MOULY and Dean of the Department KLAUS RICHTER Laurent Mouly is head of of Architecture at the KarlsKlaus Richter holds a masLM Ingénieur in Paris and ter’s degree in forestry and ruhe Institute of Technology ANDREAS KOGER was responsible for the structural engineering design has been Professor of Wood (KIT). There, among other Andreas Koger is a master of the Theatre Building near Science at the Technical things, he managed the saai carpenter and worked for University of Munich since | Archive for Architecture Erne Holzbau as the project Boulogne-sur-Mer. 2011. He is the head of the and Engineering, which leader responsible for the WOLFGANG MÜLL wood research laboratory houses the archive of works design, fabrication and Wolfgang Müll is a qualified and his work there includes of Frei Otto and the record construction of the Workshop in Andelfingen. carpenter and civil engineer. hardwood load-bearing documents for the Mannheim Multihalle. Since 1998, he has been a structures. FLORIAN KÖHLER project manager at Holzbau FRANK ZIMMERMANN Since completing his archi- Amann, where he is respon- EIKE SCHLING tectural studies in 2008, sible for the calculation and Eike Schling is an architect Frank Zimmermann is a ­Florian Köhler has been a management of timber and has been assistant pro- man­aging partner at Boll fessor at the University of Partner für Tragwerke freelance editor for Detail. construction projects. Hong Kong since 2019. He ­(formerly Boll und Partner). In that time he has written has been involved there with He took a leading role from ANNE NIEMANN numerous contributions to the design and construction conception to detailed var-­ious journals and books, Anne Niemann is an architect and is particularly including for structure – design in the Hall 10 project of doubly curved gridshell ­involved with hardwood ­published by Detail. for Messe Stuttgart. structures. load-­bearing structures. Since 2008, she has been FRANK LATTKE JAKOB SCHOOF Frank Lattke is an architect a research associate for Jakob Schoof has been the Chair of Structural and is particularly involved the editor since 2009 and with hardwood load-bearing Design under Prof. Hermann deputy chief editor of Detail Kaufmann at the Technical structures. Between 2002 since 2018. He was responsible, among other things, and 2014, he was a research University of Munich. for the magazine series associate for the Chair of and books for Detail Green ROLAND PAWLITSCHKO Structural Design under on the topic of sustainable Roland Pawlitschko is an Prof. Hermann Kaufmann build­ing and led the editorial ­architect, freelance author at the Technical University team for the journal struc-­ and architecture critic. of Munich. ture – published by Detail. He has worked as a free­ lance editor with the Detail PETER MESTEK Peter Mestek is a civil engi- editorial team since 2007. neer with Sailer Stepan & Partner and was responsible JESSICA PAWLOWSKI as project manager for the Jessica Pawlowski is a civil structural engineering design engineer and Associate of the new Pfarrzentrum at Arup. She was head of St. Josef in Holzkirchen. Arup’s multidisciplinary ­project team and co-led the structural engineering design of Terminal 2 at Mactan Airport.

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Authors AUTHORS

DEREK RATZLAFF Derek Ratzlaff is an associ-­ ate at Fast+Epp and was ­responsible with Paul Fast for the structural engineering design of the Grandview Heights Aquatic Centre.

IMAGE CREDITS RESEARCH AND TECHNOLOGY

ROOFS

MANNHEIM MULTIHALLE – POWER OF THE TEMPORARY Page 10, 11 bottom, 12, 13, 14 bottom: saai / KIT: Archive of works of Frei Otto and Carlfried Mutschler + Partner Page 11 top: saai / KIT / photo: Robert Häusser Page 14 top: Horst Hamann HARDWOOD LOADBEARING STRUCTURES Page 16, 22, 23 top and bottom: Eckhart Matthäus / Lattke Architekten Page 18 left: Lattke Architekten Page 18 right: Roman Keller Page 21 top: ETH Zurich, Institute of Structural Engineering (IBK) Page 21 right: TU Munich, Architectural Design and Timber Construction, Univ. Prof. DI Hermann Kaufmann

THE INTEGRAL STUTTGART TIMBER BRIDGE Page 36, 38 top: Burkhard Walther Page 38 bottom: MPA Stuttgart Page 40: Schaffitzel Page 41: Wilfried Dechau 60 METRES: THE TALLEST TIMBER-HYBRID HIGHRISE IN SWITZERLAND Page 42: Kuster Frey Page 44, 46 right, 48 top right, centre centre, centre right and bottom: Pirmin Jung Schweiz Page 46 top and left, 48 top left: Erne Holzbau Page 48 centre left: Manetsch Meyer Architekten

EXPERIMENTAL DOUBLY CURVED GRIDSHELL STRUCTURES Page 24, 26, 27, 29 bottom: Chair of Structural Design, TU Munich Page 25: Eberhard Möller Page 29 top: Felix Noe PRACTICAL TIMBER STRUCTURE DESIGN – WORKING WITH SPECIALIST FIRMS Page 30, 32: Jan Bitter Page 33: Holzbau Amann Page 35: Martin Granacher

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DELICATESSEN WHOLESALE STORE IN STUTTGART Page 109: Assmann Beraten CHAPEL IN SAYAMA Page 61, 62 top, 65: Hiroshi + Planen Page 111: Andreas Gabriel Nakamura & NAP Co., Ltd. Page 112–115: Page 62 bottom, 63: Koji Fujii / Nacása & Partners Inc. Annette Kisling ARCHERY HALL IN TOKYO Page 53–59: Shigeo Ogawa

STADIUM IN NICE Page 67, 72 right, 75 centre and right: Egis Bâtiments Méditerranée Page 68, 69, 74, 75 left: Milène SERVELLE Page 71: Serge Demailly Page 72 left top: Francis Vigouroux SPORTS HALL IN RILLIEUX-LA-PAPE Page 77, 83: Tectoniques Page 79 – 82: 11h45 GARAGE AND VEHICLE WORKSHOP IN ANDELFINGEN Page 85, 88 top: Erne Holzbau Page 87, 88 bottom, 89: Jürg Zimmermann SPORTS AND LEISURE POOL IN SURREY Page 91: HCMA Architekten Page 93, 94, 99: Ema Peter Photography Page 95, 96 all images except at the very top: Fast + Epp Page 96 very top: EllisDon ST. JOSEF PARISH CHURCH IN HOLZKIRCHEN Page 101, 104, top and bottom, 105: Sailer Stepan und Partner Page 102 left, 107: Martin Granacher Page 102 right, 103, 104 centre, 106: Andreas Gabriel

HEURIED SPORTS CENTRE IN ZURICH Page 117, 119 bottom, 123: Damian Poffet Page 119 top, 122 right: Filip Dujardin Page 120: Pirmin Jung Schweiz Page 122 left: Roger Frei, Zurich THE MACALLAN DISTILLERY IN ABERLOUR Page 125, 131, 132: Angus Bremner Page 127: Joas Souza Page 128: Mark Power / Magnum Photos Page 133: John Paul MACTAN AIRPORT TERMINAL 2 Page 135, 137: Rubner Holzbau Page 138: Christopher Colinares Page 140, 141: Marcel Lam Photography HALL 10 AT MESSE STUTTGART Page 143, 148: Boll Partner für Tragwerke (formerly Boll und Partner) Page 144–146: Landesmesse Stuttgart GmbH

MULTI-STOREY BUILDINGS RESIDENTIAL TOWER IN HEILBRONN Page 153, 158 top, 159 left and centre: Züblin Timber Page 155, 157, 158 bottom right, 159 right, 160: Bernd Borchardt Page 158 bottom left: Kaden+Lager

SCHÖNBUCH TOWER NEAR STUTTGART Page 209: Andreas Sporn Photography Page 210, 213: Conné van d’Grachten Page 212: schlaich bergermann partner Page 214: Stahlbau Urfer

CONFERENCE HALL IN GENEVA Page 163, 168, 169: Charpente Concept Page 164, 165, 167, 171: David Matthiessen Page 166: Behnisch Architekten THEATRE NEAR BOULOGNE-SUR-MER Page 173: Züblin Timber Page 178, 179: Studio Andrew Todd Page 174–177: Martin Argyroglo INTERNATIONAL HOUSE IN SYDNEY Page 181–185, 186 top, 188/189: Ben Guthrie Page 186 bottom: Hess Timber / Rensteph Thompson TIMBER OFFICE HIGH-RISE IN RISCH-ROTKREUZ Page 191, 194 left and centre, 196: Markus Bertschi Page 193, 194 right, 197: Roger Frei, Zurich TIMBER HIGH-RISE IN BRUMUNDDAL Page 199, 202, 204 bottom, 207 top: Moelven Limtre Page 201, 207 bottom right: EVE Images Page 207 bottom left: Øystein Elgsaas Page 204 top: Rune Abrahamsen 221

Image IMAGE CREDITS credits

PROJECT PARTICIPANTS RESEARCH + TECHNOLOGY

ROOFS

THE INTEGRAL STUTTGART TIMBER BRIDGE Arbeitsgemeinschaft Stuttgarter Holzbrücke Architects: Cheret Bozic Architekten, Stuttgart (DE) Structural engineers: knippershelbig, Stuttgart (DE) Client: Cluster Holz BW

ARCHERY HALL IN TOKYO Architects: FT Architects, Fukushima (JP) Structural engineers: Shuji Tada, Tokyo (JP) Client: Kogakuin University / Nishishinjuku Shinjuku-ku, Tokyo (JP) Site management: Daimaru House, Tokyo (JP)

60 METRES: THE TALLEST HYBRID TIMBER HIGHRISE IN SWITZERLAND Architects: Büro Konstrukt, Lucerne (CH) + Manetsch Meyer, Zurich (CH) Structural engineers: Dr. Lüchinger+Meyer, Lucerne (CH) Client: Zug Estates, Zug (CH) Timber construction engineer / Fire protection planning QS3: Pirmin Jung Schweiz, Rain (CH) Timber contractor: Erne Holzbau, Stein (CH) General contractor: Implenia, Zurich (CH)

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CHAPEL IN SAYAMA Architects: Hiroshi Nakamura & NAP, Tokyo (JP) Structural engineers: Arup, Tokyo (JP) Main contractor: Shimizu Corporation, Tokyo (JP) Roof cladding aluminium cast panels: Koizumi Alumi, Saitama (JP)

SPORTS HALL IN RILLIEUX-LA-PAPE Architects: Tectoniques Architectes, Lyon (FR) Structural engineers: Arborescence, Lyon (FR) Client: Ville de Rillieux-la-Pape (FR) Site management: Arc, Lyon (FR) Timber construction and facades: Lifteam, La Rochette (FR)

GARAGE AND VEHICLE WORKSHOP IN ANDELFINGEN Architects: Rossetti + Wyss Architekten AG, Zollikon (CH) Structural engineers: Lüchinger+Meyer Bauingenieure AG, Zurich (CH) Client: Building Department STADIUM IN NICE Zurich Canton, Zurich (CH) Architects: Timber work: Wilmotte & Associés, Paris (FR) Erne Holzbau, Stein (CH) Structural engineers: Glulam members: Egis Bâtiments Méditerranée, Hüsser Holzleimbau AG, Nice (FR) Bremgarten (CH) Structural design (roof): Egis Concept / Elioth, SPORTS AND LEISURE Montreuil (FR) POOL IN SURREY Client: Architects: Nice Éco Stadium, Nice (FR) HCMA Architecture + Design, Vancouver (CA) Structural engineers: Fast + Epp, Vancouver (CA) Client: City of Surrey (CA) General contractor: EllisDon, Vancouver (CA) Glulam elements: Western Archrib, Edmonton (CA) Prestressing elements: Dywidag-Systems International, Surrey (CA)

APPENDIX

ST. JOSEF PARISH CHURCH IN HOLZKIRCHEN Architects: Eberhard Wimmer Architekten, Munich (DE) Structural engineers: Sailer Stepan und Partner, Munich (DE) Client: Katholische Kirchenstiftung Holzkirchen, represented by the Archiepiscopal Ordinariate Munich (DE) Timber construction: Holzbau Amann, ­WeilheimBannholz (DE) Structural timber special solutions: ZT Blumer, Graz (AT) Samuel Blumer Wolfgang Müll (Holzbau Amann) DELICATESSEN WHOLESALE STORE IN STUTTGART Architects: Robertneun Architekten, Berlin (DE) Structural engineers: Assmann Beraten + Planen, Hamburg (DE) Client: FrischeParadies, Frankfurt am Main (DE) Timber construction, carpentry: Holzbau Amann, Weilheim-Bannholz (DE) HEURIED SPORTS CENTRE IN ZURICH Architects: EM2N Architekten, Zurich (CH) Structural engineers: Schnetzer Puskas Ingenieure, Zurich (CH) Structural engineering timber: Pirmin Jung Schweiz, Rain (CH) Client: City of Zurich, Amt für Hochbauten, Zurich (CH) Timber construction: Zaugg, Rohrbach (CH)

MULTI-STOREY BUILDINGS THE MACALLAN DISTILLERY IN ABERLOUR Architects: Rogers Stirk Harbour + Partners, London (GB) Structural engineers: Arup, London (GB) Landscape architects: Gillespies, London (GB) Client: Edrington, Glasgow (GB) Main contractor: Robertson Construction Group, Stirling (GB) Timber subcontractor: Wiehag, Altheim (AT)

RESIDENTIAL TOWER IN HEILBRONN Architects: Kaden+Lager GmbH, Berlin (DE) Structural engineers: bauart Konstruktions GmbH & Co. KG, Berlin (DE) Client: Stadtsiedlung Heilbronn GmbH, Heilbronn (DE) Timber construction: Züblin Timber, Aichach (DE)

CONFERENCE HALL IN GENEVA Architects: MACTAN AIRPORT Behnisch Architekten, TERMINAL 2 Stuttgart (DE) Architects: Structural engineers Integrated Design (concept): Associates – IDA, schlaich bergermann Hong Kong (CN) partner, Stuttgart (DE) Structural engineer, Building T-Ingénierie, Geneva (CH) and Civil Engineering, Ericos Lygdopoulos, Airport Planning: Geneva (CH) Arup, Hong Kong (CN) / Structural engineers Manila (PH) (construction): Client: Consortium Bois OMPI: GMR Megawide Cebu Charpente Concept, Airport Corporation, Geneva (CH) Concessionaire, Manila (PH) SJB Kempter Fitze AG, Main contractor: Herisau (CH) Megawide-GISPL Hermann Blumer, Construction Joint Venture, Herisau (CH) Cebu (PH) Ducret-Orges, Orges (CH) Timber subcontractor: Client: Rubner Holzbau, WIPO – World Intellectual Ober-Grafendorf (AT) Property Organization, Geneva (CH) HALL 10 AT MESSE STUTTGART Architects: wulf architekten, Stuttgart (DE) Structural engineers: Boll Partner für Tragwerke (ehem. Boll und Partner), Stuttgart (DE) Client: Projektgesellschaft Neue Messe, Stuttgart (DE) Roof: Fritz technologie H. Fritz, Murr (DE) 223

PROJEcT PROJECT Participants PARTICIPANTS

THEATRE NEAR BOULOGNE-SUR-MER Architects: Andrew Todd, London (GB) Structural and climate engineers: LM Ingénieur, Paris (FR) Client: Conseil Général du Pas de Calais (FR) Timber construction: Cruard SA, Simplé (FR) Cross-laminated timber elements: Merk Timber, Züblin Timber, Aichach (DE)

TIMBER HIGH-RISE IN BRUMUNDDAL Architects: Voll Arkitekter, Trondheim (NO) Structural engineers: Sweco, Lillehammer (NO) Client: Mjøstårnet AS /AB Invest, Hamar (NO) General contractor: HENT, Heimdal (NO) Timber construction: Moelven Limtre, Moelv (NO) Facade elements: RVT, Brumunddal (NO)

INTERNATIONAL HOUSE IN SYDNEY Architects: Tzannes Architects, Sydney (AU) Structural engineers: Lendlease DesignMake, Eastern Creek (AU) Client: Lendlease International Towers Sydney Trust, Sydney (AU) Timber suppliers: Stora Enso Wood Products (cross-laminated timber), Ybbs an der Donau (AT) Hess Timber (glued laminated timber), Kleinheubach (DE)

SCHÖNBUCH TOWER NEAR STUTTGART Architects and structural engineers: schlaich bergermann partner, Stuttgart (DE) Steelwork contractor: Stahlbau Urfer, Remseck (DE) Client: Förderverein Aussichtsturm im Naturpark Schönbuch, Böblingen (DE) Timber columns: Schaffitzel Holzindustrie, Schwäbisch Hall (DE)

TIMBER OFFICE HIGH-RISE IN RISCH-ROTKREUZ Architects: Burkard Meyer Architekten, Baden (CH) Structural engineers: MWV Bauingenieure, Baden (CH) Timber engineering: Erne Holzbau, Stein (CH) Client: Zug Estates, Zug (CH)

IMPRINT EDITOR Jakob Schoof

DESIGN strobo B M, Munich (strobo.eu)

EDITORIAL TEAM Roland Pawlitschko, Charlotte Petereit

TRANSLATIONS Raymond Peat PROOFREADING Meriel Clemett REPRODUCTION Repro Ludwig, AT– Zell am See

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