Designing and Constructing Prestressed Bridges

Contents Foreword vii
About the authors ix
1 Introduction 1
References 9
2 Effects of prestressing 11
2.1 Prestressing – technology 11
2.2 Effects of prestressing 16
2.3 Prestressing losses 22
References 24
3 Structural types 27
3.1 Decks of bridges of typical width 27
3.2 Deck of wide bridges 30
3.3 Bridges supported in the deck axis 34
3.4 Arch and frame bridges 34
3.5 Cable-supported bridges 37
3.6 Stress-ribbon bridges 44
References 45
4 Bridge types 47
4.1 Buried and one-span bridges 47
4.2 Motorway overpasses 49
4.3 Skew crossings 55
4.4 Urban viaducts 56
4.5 Motorway and highway viaducts 59
4.6 Bridges over rivers 67
4.7 Bridges over deep valleys 76
4.8 Footbridges 81
References 81
5 Bridge construction 83
5.1 Cast-in-place structures 83
5.2 Precast structures 96
5.3 Hybrid structures 104
References 109
6 Structural concrete 111
6.2 Behaviour of structural concrete 111
6.3 Design philosophy 113
References 114
7 Effects of concrete creep and shrinkage 115
7.1 Creep and shrinkage functions 115
7.2 Time-dependent analysis 116
7.3 Redistribution of the stresses between members of different age 117
7.4 Redistribution of the stresses due to the deformations of supports 119
7.5 Redistribution of stresses in structures in which the static systems change 119
7.6 Balancing the dead load 121
7.7 Balancing the dead load in cable-stayed structures 123
7.8 Redistribution of stresses in the decks of progressively erected structures 126
References 130
8 Analysis of concrete bridges 131
8.1 Elastic modelling of concrete bridges 131
8.2 Analysis of two basic structural types 133
8.3 Beam analysis for the box girder 134
8.4 Grillage analysis 142
8.5 Analyses of bridge decks 145
8.6 Curved structures and members 146
8.7 Cable-supported bridges 152
8.8 Curved arch and cable-supported structures 153
8.9 Strut-and-tie analyses of selected problems 157
References 162
9 Structures assembled of precast beams 165
9.1 Precast girder decks 165
9.2 Continuous structures 167
9.3 Long-span bridges 173
9.4 Precast overpasses 176
9.5 Precast arch structures 177
References 181
10 Span-by-span construction 183
10.1 Span-by-span construction of cast-in-place structures 183
10.2 Incrementally launched structures 195
10.3 Span-byspan erection of precast segmental structures 200
10.4 Progressive erection of precast segmental structures 200
References 204
11 Cantilever construction 205
11.1 Deck 205
11.2 Supports – stability of the erected structures 206
11.3 Deck above the piers 216
11.4 Design of the prestressing and camber 219
References 226
Index 227