Multi-Storey Precast Concrete Framed Structures – Kim S. Elliott (KEBT0004)

Multi-Storey Precast Concrete Framed Structures, CONTENTS:      

1 Precast Concepts, History and Design Philosophy

1.1 A Historical Note on the Development of Precast Frames 1

1.2 The Scope for Prefabricated Buildings 11

1.2.1 Modularisation and standardisation 11

1.3 Current Attitudes towards Precast Concrete Structures 17

1.4 Recent Trends in Design, and a New Deinition for Precast Concrete 21

1.5 Precast Superstructure Simply Explained 23

1.5.1 Differences in precast and cast-in situ concrete structures 23

1.5.2 Structural stability 26

1.5.3 Floor plate action 29

1.5.4 Connections and joints 30

1.5.5 Foundations 32

1.6 Precast Design Concepts 32

1.6.1 Devising a precast solution 32

1.6.2 Construction methods 36

2 Procurement and Documentation

2.1 Initial Considerations for the Design Team 43

2.2 Design Procurement 45

2.2.1 Deinitions 45

2.2.2 Responsibilities 45

2.2.3 Routes to procurement 46

2.2.4 Design ofice practice 46

2.2.5 Project design stages 48

2.2.6 Structural design calculations 49

2.2.7 Layout drawings 50

2.2.8 Component schedules and the engineer’s instructions to factory and site 54

2.3 Construction Matters 58

2.3.1 Design implications 58

2.4 Codes of Practice, Design Manuals, Textbooks and Technical Literature 60

2.4.1 Codes and Building Regulations 60

2.4.2 Non-mandatory design documents 64

2.4.3 Other literature on precast structures 67

2.5 Deinitions 68

2.5.1 General structural deinitions 68

2.5.2 Components 68

2.5.3 Connections and jointing materials 69

3 Architectural and Framing Considerations

3.1 Frame and Component Selection 71

3.2 Component Selection 75

3.2.1 General principles 75

3.2.2 Roof and loor slabs 76

3.2.3 Staircases 96

3.2.4 Roof and loor beams 101

3.2.5 Beam-to-column connections 106

3.2.6 Columns 107

3.2.7 Bracing walls 111

3.3 Special Features 113

3.3.1 Hybrid and mixed construction 113

3.3.2 Precast–in situ concrete structures 118

3.3.3 Structural steelwork and precast concrete in skeletal frames 123

3.3.4 Precast concrete with structural and glue-laminated timber 127

3.3.5 Precast concrete–masonry structures 131

3.3.6 The future of mixed construction 131

3.4 Balconies 136

4 Design of Skeletal Structures

4.1 Basis for the Design 145

4.2 Materials 148

4.2.1 Concrete 149

4.2.2 Concrete admixtures 150

4.2.3 Reinforcement 151

4.2.4 Prestressing steel 152

4.2.5 Structural steel and bolts 152

4.2.6 Non-cementitious materials 153

4.3 Structural Design 153

4.3.1 Terminology 153

4.3.2(a) Design methods 154

4.3.2(b) Reduced partial safety factors for precast design 157

4.3.3 Design of beams 162

4.3.4 Non-composite reinforced concrete beams 163

4.3.5 Beam boot design 167

4.3.6 Upstand design 172

4.3.7 Non-composite prestressed beams 183

4.3.8 Beam end shear design 198

4.3.9 Recessed beam ends 199

4.3.10 Design methods for end shear 205

4.3.11 Hanging shear cages for wide beams 211

4.3.12 Prefabricated shear boxes 217

4.4 Columns Subjected to Gravity Loads 226

4.4.1 General design 226

4.4.2 Columns in braced structures 230

4.4.3 Columns in unbraced structures 230

4.4.4 Columns in partially braced structures 230

4.5 Staircases 237

4.5.1 Reinforced concrete staircases 237

4.5.2 Prestressed concrete staircases 238

4.5.3 Staircase and landing end reinforcement 239

5 Design of Precast Floors Used in Precast Frames

5.1 Flooring Options 245

5.2 Hollow-core Slabs 249

5.2.1 General 249

5.2.2 Design 253

5.2.3 Design of cross section 257

5.2.4 Web thickness 257

5.2.5 Edge proiles 258

5.2.6 Reinforcement 260

5.2.7 Lateral load distribution 260

5.2.8 Flexural capacity 267

5.2.9 Precamber and delections 272

5.2.10 Shear capacity 275

5.2.11 Anchorage and bond development lengths 288

5.2.12 Slippage of tendons 291

5.2.13 Calculation of crack width 295

5.2.14 Cantilever design using hollow-core slabs 298

5.2.15 Bearing capacity 300

5.2.16 Wet cast hollow-core looring 301

5.2.17 Summary examples of product design data 305

5.3 Double-Tee Slabs 309

5.3.1 General 309

5.3.2 Design 312

5.3.3 Flexural and shear capacity, precamber and delections 314

5.3.4 Special design situations 315

5.4 Composite Plank Floor 315

5.4.1 General 315

5.4.2 Design 316

5.4.3 Voided composite slab 320

5.5 Precast Beam-and-Plank Flooring 324

5.5.1 General 324

5.5.2 Design of prestressed beams in the beam-and-plank looring system 325

5.6 Design Calculations 325

5.6.1 Hollow-core unit 325

6 Composite Construction

6.1 Introduction 335

6.2 Texture of Precast Concrete Surfaces 339

6.2.1 Classiication of surface textures 339

6.2.2 Surface treatment and roughness 340

6.2.3 Effects of surface preparation 341

6.3 Calculation of Stresses at the Interface 344

6.4 Losses and Differential Shrinkage Effects 346

6.4.1 Losses in prestressed composite sections 346

6.4.2 Design method for differential shrinkage 347

6.4.3 Cracking in the precast and in situ concrete 351

6.5 Composite Floors 352

6.5.1 General considerations 352

6.5.2 Flexural analysis for prestressed concrete elements 354

6.5.3 Propping 356

6.5.4 Design calculations 358

6.5.5 Ultimate limit state of shear 360

6.6 Economic Comparison of Composite and Non-composite Hollow-core Floors 364

6.7 Composite Beams 365

6.7.1 Flexural design 365

6.7.2 Propping 370

6.7.3 Horizontal interface shear 370

6.7.4 Shear check 370

6.7.5 Delections 371

7 Design of Connections and Joints

7.1 Development of Connections 375

7.2 Design Brief 377

7.3 Joints and Connections 383

7.4 Criteria for Joints and Connections 384

7.4.1 Design criteria 384

7.5 Types of Joint 386

7.5.1 Compression joints 386

7.5.2 Tensile joints 395

7.5.3 Shear joints 396

7.5.4 Flexural and torsional joints 404

7.6 Bearings and Bearing Stresses 405

7.6.1 Average bearing stresses 405

7.6.2 Localised bearing stresses 412

7.7 Connections 413

7.7.1 Pinned connections 413

7.7.2 Moment-resisting connections 413

7.8 Design of Speciic Connections in Skeletal Frames 425

7.8.1 Floor slab to beam connections 425

7.8.2 Connections at supports 426

7.8.3 Connections at longitudinal joints 430

7.8.4 Floor connections at load-bearing walls – load-bearing components 431

7.9 Beam-to-Column and Beam-to-Wall Connections 435

7.9.1 Deinitions for different assemblies 435

7.9.2 Connections to continuous columns using hidden steel inserts 436

7.9.3 Beam-to-column inserts 436

7.10 Column Insert Design 438

7.10.1 General considerations 438

7.10.2 Single-sided wide-section insert connections 442

7.10.3 Addition of welded reinforcement to wide-section inserts 453

7.10.4 Double-sided wide-section inserts 457

7.10.5 Three- and four-way wide-section connections 462

7.10.6 Narrow-plate column inserts 467

7.10.7 Cast-in sockets 468

7.10.8 Bolts in sleeves 468

7.11 Connections to Columns on Concrete Ledges 470

7.11.1 Corbels 470

7.11.2 Haunched columns 485

7.11.3 Connections to the tops of columns 491

7.12 Beam-to-Beam Connections 493

7.13 Column Splices 503

7.13.1 Types of splice 503

7.13.2 Column-to-column splices 504

7.13.3 Coupled joint splice 505

7.13.4 Welded plate splice 507

7.13.5 Grouted sleeve splice 509

7.13.6 Welded lap splice 509

7.13.7 Grouted sleeve coupler splice 510

7.13.8 Steel shoe splices 510

7.13.9 Columns spliced onto beams or other precast components 516

7.14 Column Base Connections 517

7.14.1 Columns in pockets 518

7.14.2 Columns on base plates 535

7.14.3 Columns on grouted sleeves 545

8 Designing for Horizontal Load

8.1 Introduction 547

8.2 Distribution of Horizontal Load 549

8.3 Horizontal Diaphragm Action in Precast Concrete Floors without Structural Toppings 558

8.3.1 Background 558

8.3.2 Details 559

8.3.3 Structural models for diaphragm action 561

8.3.4 Diaphragm reinforcement 567

8.3.5 Design by testing 570

8.3.6 Finite element analysis of the loor plate 574

8.4 Diaphragm Action in Composite Floors with Structural Toppings 576

8.5 Horizontal Forces due to Volumetric Changes in Precast Concrete 577

8.6 Vertical Load Transfer 581

8.6.1 Introduction 581

8.6.2 Unbraced structures 583

8.6.3 Deep spandrel beams in unbraced structures 586

8.6.4 Braced structures 586

8.6.5 Uni-directionally braced structures 590

8.6.6 Partially braced structures 590

8.7 Methods of Bracing Structures 593

8.7.1 Inill shear walls 593

8.7.2 Design methods for inill concrete walls 598

8.7.3 Design method for brickwork inill panels 603

8.7.4 Inill walls without beam framing elements 605

8.7.5 Use of slip-formed or extruded hollow-core walls as inill walls 606

8.7.6 Cantilever shear walls and shear boxes 614

8.7.7 Hollow-core cantilever shear walls 616

8.7.8 Solid cantilever shear walls 620

9 Structural Integrity and the Design for Accidental Loading

9.1 Precast Frame Integrity – The Vital Issue 627

9.2 Ductile Frame Design 628

9.2.1 Structural continuity in precast skeletal frames 628

9.3 Background to the Present Requirements 634

9.4 Categorisation of Buildings 643

9.5 The Fully Tied Solution 643

9.5.1 Horizontal ties 643

9.5.2 Calculation of tie forces 649

9.5.3 Horizontal ties to columns 654

9.5.4 Ties at balconies 659

9.5.5 Vertical ties 659

9.6 Catenary Systems in Precast Construction 662

10 Site Practice and Temporary Stability

10.1 The Effects of Construction Techniques on Design 667

10.2 Designing for Pitching and Lifting 672

10.2.1 Early lifting strengths 672

10.2.2 Lifting points 672

10.2.3 Handling 685

10.2.4 Cracks 685

10.3 Temporary Frame Stability 690

10.3.1 Propping 690

10.3.2 The effect of erection sequence 691

10.3.3 Special consideration for braced frames 692

10.3.4 Special considerations for unbraced frames 694

10.3.5 Temporary loads 696

10.4 On-Site Connections 697

10.4.1 Effect of ixing types 697

10.4.2 Strength and maturity of connections 699

10.5 Erection Procedure 699

10.5.1 Site preparation 699

10.5.2 Erection of precast superstructure 700

10.6 In situ Concrete 709

10.6.1 General speciication 709

10.6.2 Concrete screeds and joint inill in loors 711

10.6.3 Grouting 712

10.7 Handover 714

Multi-Storey Precast Concrete Framed Structures