Presetressed Concrete Structures

Description

Cover Dedication Contents Preface About the Author Chapter 1: Basic Principles 1.1 Introduction 1.2 Need for Prestressed Concrete 1.3 Brief History of Prestressed Concrete 1.4 Structural Behaviour of Prestressed Concrete Member 1.5 Methods of Prestressing 1.5.1 Pre-tensioning 1.5.2 Post-tensioning 1.6 Types of Prestressed Concrete 1.6.1 Classification as per IS:1343–19801 1.6.2 Other Classifications 1.7 Comparison with Reinforced Concrete 1.8 Applications of Prestressed Concrete 1.9 Design Code Chapter 2: Materials 2.1 Introduction 2.2 Prestressing Steel 2.2.1 High Tensile Steel 2.2.2 Need for High Tensile Steel 2.2.3 Types of Prestressing Steel 2.2.4 Modulus of Elasticity of Prestressing Steel 2.2.5 Maximum Initial Prestress in Tendon 2.3 Concrete 2.3.1 Need for High Strength Concrete 2.3.2 Compressive Strength of Concrete 2.3.3 Tensile Strength of Concrete 2.3.4 Modulus of Elasticity of Concrete 2.3.5 Time-dependent Deformation of Concrete Chapter 3: Limit State Design 3.1 Introduction 3.2 Limit States 3.3 Characteristic and Design Load 3.4 Characteristic and Design Strength of Material 3.5 Characteristic and Design Stress–Strain Curves 3.5.1 Stress–Strain Curves for Concrete 3.5.2 Stress–Strain Curves for Prestressing Steel 3.6 Design Requirements as per LSM 3.7 Limit State Design of Prestressed Concrete Members Chapter 4: Losses in Prestress 4.1 Introduction 4.2 Immediate Losses 4.2.1 Loss Due to Elastic Shortening of Concrete 4.2.2 Loss Due to Friction 4.2.3 Loss Due to Slip in Anchorage 4.3 Time Dependent Losses 4.3.1 Loss Due to Shrinkage of Concrete 4.3.2 Loss Due to Creep of Concrete 4.3.3 Loss Due to Relaxation of Steel 4.4 Total Loss in Prestress Problems Chapter 5: Analysis of Sections 5.1 Introduction 5.2 Analysis at Serviceability Limit State 5.2.1 Combined Load Approach 5.2.2 Internal Couple Approach 5.2.2.1 Kern Points 5.2.2.2 Pressure Line 5.2.3 Concept of Equivalent Loads 5.3 Load Balancing 5.4 Decompression Moment (Mdec) 5.5 Cracking Moment Mcr 5.6 Additional Stress in Tendon Due to Bending 5.7 Flexural Behaviour of Prestressed Concrete Member 5.7.1 Load Deflection Behaviour 5.7.2 Stress in Tendon 5.7.3 Modes of Failure in Flexure 5.7.4 Types of Section 5.8 Analysis at Ultimate Limit State 5.8.1 Analysis of Rectangular Sections with Bonded Tendons 5.8.2 Analysis of Post-tensioned Rectangular Beams Having Unbonded Tendons 5.8.3 Analysis of Flanged Sections Problems Chapter 6: Shear and Torsion 6.1 Introduction 6.2 Design for Shear 6.2.1 Effect of Prestress in Shear Strength 6.2.2 Identification of Zones for Shear Design 6.2.3 Ultimate Shear Resistance 6.2.4 Ultimate Shear Resistance of Concrete Vuc 6.2.5 Design of Shear Reinforcement 6.2.6 Minimum Shear Reinforcement 6.2.7 Maximum Ultimate Shear Force (Vu, max) 6.2.8 Steps for Shear Design 6.3 Design for Torsion 6.3.1 Equilibrium Torsion and Compatibility Torsion 6.3.2 Failure of Concrete Member Due to Torsion 6.3.3 Design Methods for Torsion 6.3.4 Design Provisions for Torsion as per IS:1345–1980 6.3.5 Detailing of Torsion Reinforcement 6.3.6 Steps for Torsion Design Problems Chapter 7: Anchorage Zones 7.1 Introduction 7.2 Anchorage Zones in Pre-tensioned Members 7.2.1 Bond Mechanisms 7.2.2 Transmission Length 7.2.3 Flexural Bond Length 7.2.4 Development Length 7.2.5 End Zone Reinforcement 7.3 Anchorage Zones in Post-tensioned Members 7.3.1 Bearing Stresses Behind Anchorage 7.3.2 Bursting Forces in Anchorage Zones 7.3.3 End Zone Reinforcement Problems Chapter 8: Deflections 8.1 Introduction 8.2 Deflections in Uncracked Beams 8.2.1 Short Term Deflection at Transfer Δst 8.2.2 Long Term Deflection at Service Condition Δls 8.3 Deflection of Type 3 Members 8.4 Deflection Limits Problems Chapter 9: Design of Members 9.1 Introduction 9.2 Governing Inequalities 9.3 Minimum Section Modulus 9.3.1 Minimum Section Modulus for the Top Fibre Za 9.3.2 Minimum Section Modulus for the Bottom Fibre Zb 9.4 Design of Prestressing Force 9.5 Magnel Diagram 9.6 Cable Zone 9.7 Selection of Cross-section 9.7.1 Flexural Efficiency Factor Q 9.7.2 General Guidelines for Beam Sections 9.8 Requirements for Flexural Reinforcement 9.8.1 Concrete Cover 9.8.2 Spacing of Tendons 9.8.3 Minimum Longitudinal Steel 9.8.4 Minimum Side Face Reinforcement 9.9 Design Procedure for Prestressed Concrete Members Problems Chapter 10: Composite Members 10.1 Introduction 10.2 Analysis at Serviceability Limit State 10.2.1 Stresses in Precast Web at Transfer 10.2.2 Stresses in Precast Web After Time Dependent Losses 10.2.3 Stresses in Precast Web After Casting of In-situ Slab 10.2.4 Stresses in Composite Section at Service Condition (Total Design Load Condition) 10.3 Stresses Due to Differential Shrinkage 10.4 Horizontal Shear Transfer 10.5 Ultimate Moment of Resistance 10.6 Design of Composite Members 10.6.1 Minimum Section Modulus 10.6.2 Required Prestressing Force and Allowable Cable Zone Problems Chapter 11: Indeterminate Structures 11.1 Introduction 11.2 Effects of Prestress in Indeterminate Structure 11.2.1 Primary and Secondary Moments and Shears 11.2.2 Section Moments and Concrete Moments 11.2.3 Pressure Line Due to Prestressing Force 11.2.4 Calculating the Effects of Prestress Using the Concept of Equivalent Loads 11.3 Linear Transformation of Cable Profile 11.4 Concordant Cable 11.5 Analysis of Real Cables 11.6 Calculation of Elastic Stresses in Concrete 11.7 Behaviour at Ultimate Load Problem Chapter 12: Slabs 12.1 Introduction 12.2 General Design Procedure 12.3 One-way Slabs 12.4 Edge-supported Two-way Slabs Problems Chapter 13: Circular Prestressing 13.1 Introduction 13.2 Circumferential Prestressing 13.2.1 Analysis at Transfer (Fig. 13.1(a)) 13.2.2 Analysis at Service Condition (Fig. 13.1(b)) 13.2.3 Design 13.3 Prestressed Concrete Pipes 13.4 Prestressed Concrete Circular Tanks 13.4.1 Behaviour 13.4.2 Analysis 13.4.3 Design 13.4.4 Detailing Requirements 13.5 Ring Beams 13.5.1 Analysis and Design Problems References Index