Steel–concrete composite bridges David Collings PublishedbyThomasTelfordPublishing,ThomasTelfordLtd, 1HeronQuay,LondonE144JD. www.thomastelford.com DistributorsforThomasTelfordbooksare USA:ASCEPress,1801AlexanderBellDrive,Reston,VA20191-4400,USA Japan:MaruzenCo.Ltd,BookDepartment,3–10Nihonbashi2-chome, Chuo-ku,Tokyo103 Australia:DABooksandJournals,648WhitehorseRoad,Mitcham3132, Victoria Firstpublished2005 Figures5.2,10.10,11.2courtesyofBenaim Figure10.9courtesyofTHambly Figures5.4,5.5courtesyofAmecGroupLtd Figure10.12courtesyofArup. AcataloguerecordforthisbookisavailablefromtheBritishLibrary ISBN:0727733427 #ThomasTelfordLimited2005 Allrights, including translation, reserved. Except as permitted by theCopyright, Designs and Patents Act 1988, no part of this publication may be reproduced, stored in a retrieval system ortransmittedinanyformorbyanymeans,electronic,mechanical,photocopyingorotherwise, without the prior written permission of the Publishing Director, Thomas Telford Publishing, ThomasTelfordLtd,1HeronQuay,LondonE144JD. Thisbookispublishedontheunderstandingthattheauthorissolelyresponsibleforthestate- ments made and opinions expressed in it and that its publication does not necessarily imply that such statements and/or opinions are or reflect the views or opinions of the publishers. Whileeveryefforthasbeenmadetoensurethatthestatementsmadeandtheopinionsexpressed inthispublicationprovideasafeandaccurateguide,noliabilityorresponsibilitycanbeaccepted inthisrespectbytheauthororpublishers. TypesetbyAcademicþTechnical,Bristol PrintedandboundinGreatBritainbyMPGBooks,Bodmin Dedication For my father iii Contents Foreword ix Acknowledgements x Notation xi 1. General concepts 1 Introduction 1 Structural forms 1 Materials 2 Codes 2 Concrete 3 Steel 6 Composite action 11 Shear connectors 13 2. Simple beam bridges 16 Introduction 16 Initial sizing 16 Example 2.1 16 Initial design of girder 20 Bracing of the steelwork 20 Initial design of the concrete slab 25 Initial shear connector design 26 Safety through design 26 Environmental issues 27 3. Integral bridges 29 Introduction 29 Soil–structure interaction 30 Example 3.1 31 Weathering steel 34 Compact sections 38 Portal frame structures 38 Example 3.2 38 Effects of skew 40 Example 3.3 41 v Painting 42 Shrinkage 44 Differential temperature 44 4. Continuous bridges 46 Introduction 46 Motorway widening 47 Moment–shear interaction 49 Example 4.1 50 Moment rounding 51 Cracking of concrete 53 Bearing stiffeners 55 Precamber 55 Natural frequency 57 Through-girder bridges 58 Example 4.2 60 Shear lag 61 Fatigue 63 5. Viaducts 66 Introduction 66 Concept design 66 Example 5.1 68 Articulation 69 Construction methods 71 Deck slab 74 6. Haunches and double composite action 78 Introduction 78 Haunches 78 Longitudinal shear at changes of section 79 Double composite action 80 Example 6.1 80 Slender webs 81 Lightweight concrete 83 7. Box girders 85 Introduction 85 Behaviour of boxes 85 Diaphragms 87 Example 7.1 88 Example 7.2 92 Noise from bridges 93 Shear connectors for composite boxes 94 Composite plates 95 Example 7.3 97 vi 8. Trusses 98 Introduction 98 Example 8.1 99 Member type 101 Steel sections under axial load 101 Joints in steelwork 102 Example 8.2 103 Enclosure 104 Local loading of webs 107 Continuous trusses 109 High-strength steel 110 9. Arches 111 Introduction 111 Example 9.1 112 Composite compression members 114 Example 9.2 117 Fabrication of curved sections 118 Nodes in tubular structures 118 Aesthetics 120 Tied arches 122 Example 9.3 123 Arch buckling 124 10. Cable-stayed bridges 129 Introduction 129 Deck–stay connection 130 Example 10.1 131 High-strength concrete 131 Buckling interaction 137 Shear connection 138 Towers 139 Tower top 140 Example 10.2 141 Stainless steel 142 Strain-limited composite section 143 11. Prestressed steel–concrete composite bridges 145 Introduction 145 Displacement of supports 145 Prestress using tendons 146 Design of prestressed composite structures 147 Prestress losses 148 Example 11.1 149 Durability 151 Prestressed composite box girders 151 Corrugated webs 151 Example 11.2 152 Extra-dosed bridges 153 vii 12. Assessment of composite bridges 155 Introduction 155 History 155 Structure types 157 Inspection 157 Loads 157 Materials 159 Testing of the shear connection 160 Analysis 160 Incidental and partial composite action 161 Cased beams 161 Strengthening 162 Life-cycle considerations 162 Appendix A: Approximate methods 164 Appendix B: Calculation of section properties 165 Section properties for steel sections 165 Section properties for steel–concrete composite sections 165 Section properties for cracked steel–concrete composite sections with reinforcement 166 Appendix C: Section properties for examples 167 Appendix D: Plastic section properties for steel–concrete composite sections 168 Appendix E: Torsional properties for steel–concrete composite sections 170 Appendix F: Moment–axial load interaction for compact steel–concrete composite sections 171 References 172 Index 177 viii Foreword The bridge crossing it, with its numberless short spans and lack of bigness, beauty and romance he gazed upon in instant distain. It appeared to creep, cringing and apologetic, across the wide waters which felt the humiliation of its presence...Yet he received a shock of elation as the train had moved slowly along the bridge, carrying him with it, and he gazed downward upon flowing waters, again he marvelled at what men could do; at the power of men to build; to build a bridge so strong... [1]. I see this book as a journey. A journey of experience from the first simple river crossing to the more complex suspended spans of the early twenty-first century. A journey across the world from the bleak post-industrial landscapes that are still scattered across Britain, around the broad untamed rivers of Bengal and into the racing development of South East Asia. But it is also a subjective journey, over and under the numberless spans of motorway bridges that are the ‘bread and butter’ of many bridge designers, through to the countless bridges that perform their task with pride, and always marvelling at how we build so strong, always questioning. ThisbookhasitsoriginsinthecompositebridgechapteroftheManualofBridge Engineering[139].Thisbookexpandsuponthatchapterandprovidesdetailsofmore steel–concrete composite bridges. It is intended to show how composite bridges may be designed simply from basic concepts without the need for a clause-by- clause checking of codes and standards. All chapters use examples of various bridges to illustrate the design and construction methods. The book looks impar- tially at this construction form and compares composite bridges with other types, and often places limits on their use. The book is intended for a number of readers, first those who use the Manual of Bridge Engineering and wish to find more detail on steel–concrete composite bridges. Second, it is for those engaged in design who require a deeper understanding of the methods used as well as how they are verified against design codes. The book aims to show how to choose the bridge form, and design element sizes to enable drawings to be produced. The book covers a wide range of examples, in all of which the author has had an involvement or interest. ix Acknowledgements Many of the examples and photographs are derived from work carried out at Benaim, and the support of the staff and directors is gratefully acknowledged. Particular thanks go to Rup Shandu for his help with drafting some of the more complex figures and to Robert Henderson for patiently reading the drafts of each chapter. I would like to thank John Bowes and Phil Girling for the aerial views of the Doncaster Viaduct and Brian Bell for the photographs of the Irish bridges, not all of which were used in the final version. I am also indebted to Naeem Hussain and Steve Kite of Arup for the information on the Stonecutters Bridge tower, and to Sally Sunderland for the information on Brunel’s Paddington Bridge. x Notation A area A steel area a A composite section ac A concrete area c A reinforcing steel area s B width D depth of girder, rigidity E Young’s modulus E steel modulus of elasticity a E concrete modulus of elasticity c E long-term concrete modulus c0 F force or load F force on fixed bearings F G permanent load, shear modulus H height I second moment of area J torsional constant J mass moment of inertia m K stiffness of member, soil pressure coefficient L length of beam or slab L effective length e M moment M design resistance moment D M design resistance moment of flanges f M ultimate moment u M0 reduction of moment N axial load N design resistance load D No number of connectors N chord plastification-k joint pk N chord plastification-x joint px N ultimate axial resistance u N squash load ul P load on single connector, bolt capacity, wind susceptibility factor P initial prestress i P prestress force after losses o P resistance of a connector u P resistance of a connector in lightweight concrete UL xi