Prestressed Concrete

Transcription

1 N. Rajagopalan Prestressed Concrete Alpha Science International Ltd. Pangbourne England

2 Contents Foreword Preface Acknowledgements Notations v vii xi xiii 1. Introduction Development of Prestressed Concrete Advantages of Prestressed Concrete Classification of Types of Prestressing Tendons and Cables Concepts of Prestressing 12 References Materials Introduction Concrete High Tensile Steel Corrosion of Prestressing Steel Modern Materials 61 References Prestressing Systems and Devices General Anchorage by Embedment Anchorage by External Components Couplers Non-Conventional Prestressing 74 References Analysis for Flexure (Prestressed Concrete Elements) General Behaviour of Prestressed Concrete Elements in Flexure Basic Assumptions Notations General Concept of Stresses Prestressing Force Transferred by Pretensioning System 86

3 xviii Contents 4.7 Prestressing Force Transferred by Post Tensioning System Resultant Compression Line (C.G.C. line) Load Balancing Concept 115 References Losses in Prestress Introduction Immediate losses Time dependent losses 140 References Ultimate Strength in Flexure General Failure of Beam by Fracture of Steel Failure of Under Reinforced Beams Failure of Over Reinforced Beams Balanced Beam Design Failure Loads and Moments Evaluation of Failure Load/Failure Moment Code Provisions 173 References Philosophy of Design Introduction Concepts of Limit States and Partial Safety Factors Design Loads and Stresses Limit State of Collapse Limit State of Serviceability 201 References Design for Flexure Introduction Flexural Design Using Allowable Stresses at Service Load Stress Range Approach Lins Approach Magnel's Approach 239 References Shear and Torsional Behaviour (Analysis and Design) Concept of Shear Mechanism of Shear Resistance in Concrete Beams Design for Shear in Prestressed Concrete Beams Shear in Flanged Beams Concept of Torsion Behaviour of Structural Elements Under Torsion Failure of Concrete Elements Under Torsion 278

4 Contents xix 9.8 IS Code Provisions British Code Provision BS American Code Specification ACI References Transmission and Anchorage Zone (Analysis and Design) General Pretensioned Prestressed Concrete Elements Post Tensioned Prestressed Concrete Elements Indian Standards Code Provisions FIP Recommendations 1984 Specifications BS Specifications Detailing of Reinforcement in General 329 References Composite Construction General Need for Composite Construction Types of Composite Construction Behaviour of Composite Construction Flexural Stresses Longitudinal Shear Transfer Transverse Shear Creep and Shrinkage Effects in Composite Construction Stage Prestressing Additional Design Considerations 351 References Statically Indeterminate Structures (Analysis and Design) General Analysis of Prestressed Indeterminate Structures Continuous Beams Linear Transformation and Concordancy of Cable Profiles Frames Choice of Prestressing and Cable Profiles Comparison for Choice for Best Profile Effect of Time Dependent Deformation on Indeterminate Prestressed Concrete Structures 385 References Cylindrical Structures in Prestressed Concrete Pipes and Tanks (Analysis and Design) General 388

5 xx Contents 13.2 Prestressed Concrete Pipes Types of Prestressed Concrete Pipes Unique Properties of Non-Cylinder Prestressed Pipes Advantages of Prestressed Concrete Pipes Loads on Pipes Design of Prestressed Concrete Pipes Design of Prestressed Concrete Non Cylinder Pipes Prestressed Concrete Water Tanks Choice of Shape of Tanks Structural Behaviour of Cylindrical Tanks Design Effects of Prestressing Design for Flexure in Vertical Plane Influence Line for Moments in Vertical Plane Design Procedure Design Example Construction Problems 427 References Partial Prestressing (Principles, Analysis and Design Concepts) General Case for Partial Prestressing Partial Prestressing and the Codes of Practice Definitions for Partial Prestressing Analysis Design Cracks and Crack width 449 References Other Structures General Flat Slabs Two Sides Supported Slabs Skew Slabs Folded Plates Cylindrical Shell Structures Doubly Curved Shell Structures 476 References 477 SUBJECT INDEX 479