Prestressed Concrete Bridges Design and Construction

Contents Preface to the 2nd Edition x
Preface to the 1st Edition xi
Dedication xii
Acknowledgements xiii
1 Prestressed concrete in bridgeworks 1
Introduction 1
Principles of prestressing 5
Pre-tensioning 6
Post-tensioning 7
Brief history of prestressed concrete bridges 7
References 21
2 Prestressing components and equipment 23
Introduction 23
Proprietary systems 23
Wires 24
Strands and multi-strand tendons 24
Bars 27
Anchorages 27
Tendon couplers 29
Ducting 31
Equipment for placing tendons 33
Stressing jacks 33
Health and safety 35
References 37
3 Durability and detailing 39
Introduction 39
Recent history of durability issues in the UK 28
Corrosion of post-tensioning outside the UK 41
Corrosion protection and ducting 41
Concrete 42
Detailing 44
Access 45
Stray current protection 46
External tendon replacement 48
References 50
4 Grouting post-tensioned tendons 51
Introduction 51
Recent history of grouting 51
Grout material 53
Grout material tests 55
Grouting equipment 56
Vents and other details 57
Grouting trials 59
Pre-grouting test (pressure testing) of the ducting system 60
Air pressure testing 60
Water pressure testing 61
Leakages 62
Grouting procedure 63
Grease and wax grout 64
References 64
5 Prestress design and application 67
Introduction 67
General approach 67
Primary and secondary prestress effects 70
Prestress force and losses 74
Friction losses and tendon extension 74
Elastic shortening and strains 76
Relaxation of tendon steel 77
Creep losses 78
Shrinkage losses 79
Tendon eccentricity in ducts 80
Serviceability limit state stress check 81
Deflections and pre-camber 84
Vibrations and fatigue in tendons 84
Ultimate moment design 85
Shear design 87
Torsion design 89
Longitudinal shear 90
Partial prestressing 90
Construction sequence and creep analysis 91
Temperature effects 93
Concrete properties 95
Application of the prestress 97
Design procedures to Eurocode 2 (BSI, 2004a, 2005a, 2004b and 2005b) 97
Design procedures to BS 5400 (BSI, 1990) 102
Design procedures to AASHTO standard specifications
(AASHTO, 1998-2011) 107
References 110
6 Design of details 111
Introduction 111
Anchorages 111
Pre-tensioned strand 111
Post-tensioned tendons 113
Cast-in dead-end anchors for post-tensioned tendons 117
Anchor blisters or blocks 117
Anchor pockets 120
Couplers 121
Ducts 122
Diaphragms 124
Deviators 129
References 134
7 Concept design of prestressed concrete bridges 135
Introduction 135
Deck types 135
Selecting the deck arrangement 141
Articulation and span arrangements 143
Post-tensioning with internal or external tendons 144
Bridge costs 145
Material quantities 146
References 147
8 Analysis of prestressed concrete bridges 149
Introduction 149
Traditional approach to deriving forces, moments and shears 149
Dead load and applied loading analysis 149
Deriving the prestress forces and moments 151
Stage-by-stage and creep effects 155
Combining effects 156
Specialist software for the analysis of prestressed concrete bridges 156
General description 156
Input data 158
Analysis of the structure 161
Output 162
Summary 162
References 163
9 Slab bridges 165
Introduction 165
Solid-slab bridges 166
Voided-slab bridges 167
Design of slab bridges 169
References 170
10 Beam-and-slab bridges 171
Introduction 171
General arrangement 174
Construction of in situ beam-and-slab decks 179
Casting and transportation of precast beams 181
Erection of precast beams 186
Casting of deck slab 187
Design of beam-and-slab decks 189
General design 189
Stress distribution through section 190
Precast beams in continuous and integral decks 193
Prestress and reinforcement 194
References 195
11 In situ multi-cell box girder decks 197
Introduction 197
General arrangement 197
Construction of in situ multi-cell box girders 199
Design od in situ multi-cell box girders 205
References 207
12 In situ single-cell box girder bridges 209
Introduction 209
General arrangement 209
Construction, span by span 213
Construction by balanced cantilever 216
Design of in situ single-cell box girders 221
Box behaviour 221
Prestress layout 221
Transverse prestressing of top slab 223
Deck articulation 223
Deck construction 224
References 224
13 Precast segmental match-cast decks 225
Introduction 225
General arrangement 228
Casting of segments 230
Storage and transportation of segments 240
Segment erection 243
Design aspects associated with precast segmental decks 264
Prestress tendon layout 264
References 275
14 Precast full-length box girders 277
Introduction 277
General arrangement 280
Casting and storage of the units 280
Transportation of the units 283
Erection of the units 286
Design of full-length precast box girder decks 288
15 Incrementally launched box girder bridges 291
Introduction 291
General arrangement 291
Casting the deck 296
Launching the deck 301
Design aspects associated with launched box girder decks 306
Longitudinal design during launch 306
Transverse and local design during launch 307
Construction tolerances 307
Construction loading 310
Loads on supports during launching 311
References 311
16 Cable-stayed bridges 313
Introduction 313
Cable-stayed bridge arrangements 315
Construction of concrete cable-stayed bridges 318
Box girder decks 320
Beam-and-slab decks 321
Design aspects associated with concrete cable-stayed bridges 325
Analysis of cable-stayed bridges 328
Deck design and behaviour 331
Deck dynamic behaviour 333
Stays 335
Temporary loading 335
References 337
17 Other prestressed concrete bridge types 339
Introduction 339
Extradosed bridges 339
Fin-back bridges 339
Truss bridges 340
Arch bridges 342
Footbridges 345
References 347
18 Problems and failures 349
Introduction 349
Prestressing components 349
Concrete and reinforcement 352
Problems during construction 355
Structural behaviour problems 358
Problems after opening 359
References 360
Appendix A Definitions 361
Appendix B Symbols and notation used 363
Appendix C Bibliography, further reading and useful references 369
C.1. Introduction 369
C.2 Books 369
C.3 Design guides and technical reports 370
C.4 Articles 371
C.5 Standards, Codes of Practice and Specifications 372
C.6 Websites 374
Appendix D Proprietary systems 377
D.1 Introduction 377
D.2 Multi-strand systems 377
D.3 External tendons systems 384
D.4 Flat slab systems 386
D.5 Bar systems 388
D.6 Wire prestressing systems 395
D.7 Auxiliary equipment 398
Index 401