WI LEY Blackwell. Multi-storey Precast Concrete Framed Structures. Colin K. Jolly MSc, PhD, CEng, MICE, FIStructE

Transcription

1 Multi-storey Precast Concrete Framed Structures Kim S. Elliott BTech, PhD, CEng, MICE Colin K. Jolly MSc, PhD, CEng, MICE, FIStructE WI LEY Blackwell

2 Contents Preface Notation Precast Concepts, History and Design Philosophy 1.1 A Historical Note on the Development of Precast Frames 1.2 The Scope for Prefabricated Buildings Modularisation and standardisation 1.3 Current Attitudes towards Precast Concrete Structures 1.4 Recent Trends in Design, and a New Definition for Precast Concrete 1.5 Precast Superstructure Simply Explained Differences in precast and cast-in situ concrete structures Structural stability Floor plate action Connections and joints Foundations 1.6 Precast Design Concepts Devising aprecast solution Construction methods 2 Procurement and Documentation 2.1 Initial Considerations for the Design Team 2.2 Design Procurement Definitions Responsibilities Routes to procurement Design office practice Project design stages Structural design calculations Layout drawings Component schedules and the engineer's instructions to factory and site 2.3 Construction Matters Design implications 2.4 Codes of Practice, Design Manuals, Textbooks and Technical Literature Codes and Building Regulations Non-mandatory design documents Other literature on precast structures 2.5 Definitions General structural definitions Components Connections and jointing materials IX XI

3 iv Contents 3 Architectural and Framing Considerations 3.1 Frame and Component Selection 3.2 Component Selection General principles Roof and floor slabs Staircases Roof and floor beams Beam-to-column connections Columns Bracing walls 3.3 Special Features Hybrid and mixed construction Precast-in situ concrete structures Structural steelwork and precast concrete in skeletal frames Precast concrete with structural and glue-laminated timber Precast concrete-masonry structures The future of mixed construction 3.4 Balconies Design of Skeletal Structures 4.1 Basis for the Design 4.2 Materials Concrete Concrete admixtures Reinforcement Prestressing steel Structural steel and bolts Non-cementitious materials 4.3 Structural Design Terminology 4.3.2(a) Design methods 4.3.2(b) Reduced partial safety factors for precast design Design of beams Non-composite reinforced concrete beams Beam boot design Upstand design Non-composite prestressed beams Beam end shear design Recessed beam ends Design methods for end shear Hanging shear cages for wide beams Prefabricated shear boxes 4.4 Columns Subjected to Gravity Loads General design Columns in braced structures Columns in unbraced structures Columns in partially braced structures 4.5 Staircases Reinforced concrete staircases Prestressed concrete staircases Staircase and landing end reinforcement

4 Contents v 5 Design of Precast Floors Used in Precast Frames Flooring Options Hollow-core Slabs General Design Design of cross section Web thickness Edge profiles Reinforcement Lateral load distribution Flexural capacity Precamber and deflections Shearcapacity Anchorage and bond development lengths Slippage oftendons Calculation of crack width Cantilever design using hollow-core slabs Bearing capacity Wet cast hollow-core flooring Summary examples of product design data Double-Tee Slabs General Design Flexural and shear capacity, precamber and deflections Special design situations Composite Plank Floor General Design Voided composite slab Precast Beam-and-Plank Flooring General Design of prestressed beams in the beam-and-plank flooring system Design Calculations Hollow-core unit Composite Construction Introduction Texture of Precast Concrete Surfaces Classification of surface textures Surface treatment and roughness Effects of surface preparation Cakulation of Stresses at the Interface Losses and Differential Shrinkage Effects Losses in prestressed composite sections Design method for differential shrinkage Cracking in the precast and in situ concrete Composite Floors General considerations Flexural analysis for prestressed concrete elements Propping Design calculations Ultimate limit state of shear 360

5 vi Contents 6.6 Economic Comparison of Composite and Non-composite Hollow-core Floors Composite Beams Flexural design Propping Horizontal interface shear Shear check Deflections Design of Connections and Joints Development of Connections Design Brief Joints and Connections Criteria for Joints and Connections Design criteria Types of Joint Compression joints Tensile joints Shear joints Flexural and torsional joints Bearings and Bearing Stresses Average bearing stresses Localised bearing stresses Connections Pinned connections Moment-resisting connections Design of Specific Connections in Skeletal Frames Floor slab to beam connections Connections at supports Connections at longitudinal joints Floor connections at load-bearing walls -load-bearing components Beam-to-Column and Beam-to-Wall Connections Definitions for different assemblies Connections to continuous columns using hidden steel inserts Beam-to-column inserts Column Insert Design General considerations Single-sided wide-section insert connections Addition of welded reinforcement to wide-section inserts Double-sided wide-section inserts Three- and four-way wide-section connections Narrow-plate column inserts Cast-in sockets Bolts in sleeves Connections to Columns on Concrete Ledges Corbels Haunched columns Connections to the tops of columns Beam-to-Beam Connections Column Splices Types of splice Column-to-column splices 504

6 Contents vii Coupled joint splice Welded plate splice Grouted sleeve splice Welded lap splice Grouted sleeve coupler splice Steel shoe splices Columns spliced onto beams or other precast components 7.14 Column Base Connections Columns in pockets Columns on base plates Columns on grouted sleeves 8 Designing for Horizontal Load 8.1 Introduction 8.2 Distribution of Horizontal Load 8.3 Horizontal Diaphragm Action in Precast Concrete Floors without Structural Toppings Background Details Structural models for diaphragm action Diaphragm reinforcement Design by testing Finite element analysis of the floor plate 8.4 Diaphragm Action in Composite Floors with Structural Toppings 8.5 Horizontal Forces due to Volumetrie Changes in Precast Concrete 8.6 Vertical Load Transfer Introduction Unbraced structures Deep spandrei beams in unbraced structures Braced structures Uni-directionally braced structures Partially braced structures 8.7 Methods of Bracing Structures Infill shear walls Design methods for infill concrete walls Design method for brickwork infill panels Infill walls without beam framing elements Use of slip-formed or extruded hollow-core walls as infill walls Cantilever shear walls and shear boxes Hollow-core cantilever shear walls Solid cantilever shear walls 9 Structural Integrity and the Design for Accidental Loading 9.1 Precast Frame Integrity - The Vital Issue 9.2 Ductile Frame Design Structural continuity in precast skeletal frames 9.3 Background to the Present Requirements 9.4 Categorisation of Buildings 9.5 The Fully Tied Solution Horizontal ties Calculation of tie forces

7 viii Contents Horizontal ties to columns Ties at balconies Vertical ties 9.6 Catenary Systems in Precast Construction 10 Site Practice and Temporary Stability 10.1 The Effects of Construction Techniques on Design 10.2 Designing for Pitching and Lifting Early lifting strengths Lifting points Handling Cracks 10.3 Temparary Frame Stability Propping The effect of erection sequence Special consideration far braced frames Special considerations far unbraced frames Temporary loads 10.4 On-Site Connections Effect of fixing types Strength and maturity of connections 10.5 Erection Procedure Site preparation Erection of precast superstructure 10.6 In situ Concrete General specification Concrete screeds and joint infill in floars Grouting 10.7 Handover References Index