Post-tensioned concrete floors

Front Cover......Page 1
Post-tensioned Concrete Floors......Page 4
Copyright Page......Page 5
CONTENTS......Page 6
INTRODUCTION......Page 10
NOTATIONS......Page 12
1.1 Introduction......Page 16
1.2 Prestressing in principle......Page 17
1.3 Stress reversal......Page 20
1.4 Tendons......Page 21
1.5 Prestress losses......Page 22
1.6 Initial and final stresses......Page 23
1.7 Pre-tensioning and post-tensioning......Page 24
1.8 Reinforced and post-tensioned concrete floors......Page 25
1.9 Bonded and unbonded post-tensioning......Page 29
1.10 Stressing stages......Page 32
1.13 Holes through completed floors......Page 33
1.14 Post-tensioning in refurbishment......Page 34
1.15 Some misconceptions about post-tensioned floors......Page 35
2.1 Formwork......Page 39
2.2 Dense concrete......Page 41
2.3 Lightweight concrete......Page 50
2.4 Post-tensioning tendons......Page 54
2.5 Prestressing hardware......Page 62
2.6 Equipment......Page 70
3.1 General......Page 76
3.2 Structural elements of a floor......Page 79
3.3 Panel configuration......Page 85
3.4 Span to depth ratio......Page 89
4.1 Design objectives and buildability......Page 94
4.2 Restraint from vertical elements......Page 97
4.3 Dispersion of the prestressing force......Page 100
4.4 Column moments......Page 102
4.5 Movements in a concrete floor......Page 105
4.6 Crack prevention......Page 106
4.7 Tendon profile......Page 108
4.8 Access at the live end......Page 109
4.9 Transfer beams......Page 111
4.10 Durability......Page 112
4.11 Fire protection......Page 114
4.12 Minimum and maximum prestress......Page 117
4.13 Additional considerations for structures in seismic zones......Page 118
5.1 General......Page 123
5.2 Equivalent load......Page 124
5.3 Secondary moments......Page 127
5.5 Tendon profile elements......Page 129
5.6 Composite profiles......Page 137
5.7 Tendon deviation in plan......Page 144
5.8 Clash of beam and slab tendons......Page 145
6.1 The design process......Page 147
6.2 Options in a design......Page 149
6.3 Computer programs......Page 151
6.4 Partial prestressing......Page 152
6.5 Permissible stresses in concrete......Page 153
6.6 Permissible stresses in strand......Page 156
6.7 Analysis......Page 157
6.8 Simply supported span......Page 159
6.9 Continuous spans......Page 162
7.1 General......Page 175
7.2 Friction losses......Page 178
7.3 Anchorage draw-in......Page 179
7.4 Elastic shortening......Page 183
7.5 Shrinkage of concrete......Page 185
7.6 Creep of concrete......Page 186
7.7 Relaxation of tendons......Page 187
7.9 Tendon force from elongation......Page 188
8.1 Failure mechanisms......Page 192
8.2 Level of prestress......Page 195
8.3 Applied loads......Page 196
8.4 Procedure for calculating the strength......Page 197
8.5 Ultimate stresses......Page 200
8.6 Strain compatibility......Page 204
8.7 Anchorage zone......Page 206
9.1 Deflections......Page 213
9.2 Vibration......Page 221
CHAPTER 10. SHEAR......Page 236
10.1 Shear strength of concrete......Page 237
10.2 Beams and one-way slabs......Page 239
10.3 Two-way slabs......Page 245
10.4 Alternatives to conventional shear reinforcement......Page 255
CHAPTER 11. SLABS ON GRADE......Page 264
11.1 The design process......Page 265
11.2 Factors affecting the design......Page 266
11.3 Traditional RC floors......Page 272
11.4 Post-tensioned ground floors......Page 274
11.5 Elastic analysis......Page 276
11.6 Construction......Page 282
12.1 Drawings and symbols......Page 286
12.2 Minimum reinforcement......Page 289
12.3 Tendon spacing and position......Page 291
12.5 Movement joints......Page 292
12.6 Detailing for seismic resistance......Page 296
CHAPTER 13. SITE ACTIVITIES AND DEMOLITION......Page 299
13.1 Storage of materials......Page 301
13.2 Installation......Page 302
13.3 Concreting......Page 303
13.4 Stressing......Page 304
13.5 Grouting......Page 309
13.7 Demolition......Page 310
13.8 Cutting holes......Page 318
REFERENCES......Page 321
INDEX......Page 324