DISPLACEMENT-BASED SEISMIC DESIGN OF STRUCTURES

Transcription

1 DISPLACEMENT-BASED SEISMIC DESIGN OF STRUCTURES M.].N. PRIESTLEY Centre oe Research and Graduate Studies in Earthquake Engineering and Engineering Seismology (ROSE School), Istituto Universitario di Studi Superiori (IUSS), Pavia, Italy G.M. CALVI Department oe Structural Mechanics, Universid degli Studi di Pavia, Pavia, Italy M.]. KOWALSKY Department oe Civil, Construction, and Environmental Engineering, North Carolina State University, Raleigh, USA IUSS PRESS, Pavia, ITALY

2 CONTENTS Preface 1 Introduction: The Need for Displacement-Based Seismic Design 1.1 Historical Considerations 1.2 Force-Based Seismic Design 1.3 Problems with Force-Based Seismic Design Interdependency of Strength and Stiffness Period Calculation Ductility Capacity and Force-Reduction Factors Ductility of Structural Systems Relationship between Strength and Ductility Demand Structural Wall Buildings with Unequal Wall Lengths Structures with Dual (Elastic and Inelastic) Load Paths Relationship between Elastic and Inelastic Displacement Demand Summary 1.4 Development of Displacement-Based Design Methods Force-Based/Displacement Checked Deformation-Calculation Based Design Deformation-Specification Based Design Choice of Design Approach 2 Seismic Input for Displacement-Based Design 2.1 Introduction: Characteristics of Accelerograms 2.2 Response Spectra Response Spectra from Accelerograms Design Elastic Spectra Influence of Damping and Ductility on Spectral Displacement Response 2.3 Choice of Accelerograms for Time History Analysis 3 Direct Displacement-Based Design: Fundamental Considerations 3.1 Introduction 3.2 Basic Formulation of the Method v xv

3 vi Priestley, Calvi and Kowalsky. Displacement-Based Seismic Design of Structures Example 3.1 Basic DDBD Design Limit States and Performance Levels Section Limit States Structure Limit States Selection of Design Limit State Single-Degree-of-Freedom Structures Design Displacement for a SDOF structure Yield Displacement Equivalent Viscous Damping Design Base Shear Equation Design Example 3.3: Design of a Simple Bridge Pier Design When the Displacement Capacity Exceeds the Spectral Demand Example 3.4: Base Shear for a Flexible Bridge Pier Multi-Degree-of-Freedom Structures Design Displacement Displacement Shapes Effective Mass Equivalent Viscous Damping Example 3.5: Effective Damping for a Cantilever Wall Building Distribution of Design Base Shear Force Analysis of Structure under Design Forces Design Example 3.6: Design moments for a Cantilever Wall Building Design Example 3.7: Serviceability Design far a Cantilever Wall Building P-~ Effects Current Design Approaches Theoretical Considerations Design Recommendations for Direct Displacement-based Design Combination of Seismic and Gravity Actions A Discussion ofcurrent Force-Based Design Approaches Combination of Gravity and Seismic Moments in Displacement-Based Design Consideration oftorsional Response in Direct Displacement-Based Design Introduction Torsional Response of Inelastic Eccentric Structures Design to Inc1ude Torsional Effects Capacity Design for Direct Displacement-Based Design Some Implications of DDBD Influence of Seismic Intensity on Design Base Shear Strength

4 Contents vii Influenee of Building Height on Required Frame Base Shear Strength Bridge with Piers of Different Height Building with Unequal Wall Lengths Analysis Tools for Direct Displacement-Based Design Introduction Foree-Displaeement Response of Reinforeed Conerete Members Moment-Curvature Analysis Conerete Properties for Moment-Curvature Analysis Masonry Properties for Moment-Curvature Analyses Reinforcing Steel Properties for Moment-Curvature Analyses Strain Limits for Moment-Curvature Analysis Material Design Strengths for Direet Displaeement-Based Design Bilinear Idealization of Conerete Moment-Curvature Curves Foree-Displaeement Response from Moment-Curvature Computer Program for Moment-Curvature and Foree-Displacement Foree-Displaeement Response of Steel Members Elastie Stiffness of Craeked Conerete Seetions Cireular Conerete Columns Rectangular Conerete Columns Walls Flanged Reinforeed Conerete Beams Steel Beam and Column Seetions Storey Yield Drift of Frames Summary ofyield Deformations Analyses Related to Capacity Design Requirements Design Example 4.1: Design and Overstrength of a Bridge Pier Based on Moment-Curvature Analysis Default Overstrength Faetors Dynamie Amplifieation (Higher Mode Effeets) Equilibrium Considerations in Capacity Design Dependable Strength of Capacity Proteeted Aetions Flexural Strength Beam/ColumnJoint Shear Strength Shear Strength of Conerete Members: Modified UCSD model Design Example 4.2: Shear Strength of a Cireular Bridge Column Shear Strength of Reinforeed Conerete and Masonry Walls Response to Seismie Intensity Levels Exeeeding the Design Level 185

5 viii Priestley, Calvi and Kowalsky. Displacement-Based Seismic Design of Structures Shear Flexibility of Concrete Members Computation of Shear Deformations Design Example 4.3 Shear Deformation, and Failure Displacement of a Circular Column Analysis Tools for Design Response Verification Introduction Inelastic Time-History Analysis for Response Verification Non-Linear Static (Pushover) Analysis Frame Buildings 5.1 Introduction 5.2 Review ofbasic DDBD Process for Frame Buildings SDOF Representation ofmdof Frame Design Actions for MDOF Structure from SDOF Base Shear Force Design Inelastic Displacement Mechanism for Frames 5.3 Yield Displacements of Frames Influence on Design Ductility Demand Elastically Responding Frames Yield Displacement of Irregular Frames Design Example 5.1: Yield Displacement and Damping of an Irregular Frame Yield Displacement and Damping when Beam Depth is Reduced with Height Yield Displacement of Steel Frames 5.4 Controlling Higher Mode Drift Amplification 5.5 Structural Analysis Under Lateral Force Vector Analysis Based on Relative Stiffness ofmembers Analysis Based on Equilibrium Considerations 5.6 Seetion Flexural Design Considerations Beam Flexural Design Column Flexural Design 5.7 Direct Displacement-Based Design of Frames for Diagonal Excitation 5.8 Capacity Design for Frames General Requirements Beam Flexure Beam Shear Column Flexure Column Shear 5.9 Design Verification Displacement Response Column Moments Column Shears

6 Contents ix Column Axial Forces Design Example 5.2: Member Design Forces for an Irregular Two-Way Reinforced Concrete Frame Precast Prestressed Frames Seismic Behaviour of Prestressed Frames with Bonded Tendons Prestressed Frames with Unbonded Tendons Hybrid Precast Beams Design Example 5.3: DDBD of a Hybrid Prestressed Frame Building including P-~ Effects Masonry Infllled Frames Structural Options Structural Action of Intill DDBD of Intilled Frames Steel Frames Structural Options Concentric Braced Frames Eccentric Braced Frames Design Example 5.4: Design Verification ofdesign Example 5.1/ Structural Wall Buildings 6.1 Introduction: Some Characteristics ofwall Buildings Section Shapes Wall Elevations Foundations for Structural Walls Inertia Force Transfer into Walls 6.2 Review ofbasic DDBD Process for Cantilever Wall Buildings Design Storey Displacements 6.3 Wall Yield Displacements: Significance to Design Influence on Design Ductility Limits Elastically Responding Walls Multiple In-Plane Walls 6.4 Torsional Response of Cantilever Wall Buildings Elastic Torsional Response Torsionally Unrestrained Systems Torsionally Restrained Systems Predicting Torsional Response Recommendations for DDBD Design Example 6.1: Torsionally Eccentric Building Simplification of the Torsional Design Process 6.5 Foundation Flexibility Effects on Cantilever Walls Influence on Damping Foundation Rotational Stiffness

7 x Priestley, Calvi and Kowalsky. Displacement-Based Seismic Design of Structures Capacity Design far Cantilever Walls Modified Modal Superposition (MMS) for Design Forces in Cantilever Walls Simplified Capacity Design for Cantilever Walls Precast Prestressed Walls Coupled Structural Walls General Characteristics Wall Yield Displacement Coupling Beam Yield Drift Wall Design Displacement Eguivalent Viscous Damping Summary of Design Process Design Example 6.3: Design ofa Coupled-Wall Building Dual Wall-Frame Buildings 7.1 Introduction 7.2 DDBD Procedure Preliminary Design Choices Moment Profiles for Frames and Walls Moment Profiles when Frames and Walls are Connected by Link Beams Displacement Profiles Eguivalent Viscous Damping Design Base Shear Force Design Results Compared with Time History Analyses 7.3 Capacity Design for Wall-Frames Reduced Stiffness Model far Higher Mode Effects Simplified Estimation of Higher Mode Effects for Design 7.4 Design Example 7.1: Twelve Storey Wall-Frame Building Design Data Transverse Direction Design Longitudinal Direction Design Comments on the Design Masonry Buildings 8.1 Introduction: Characteristics of Masonry Buildings General Considerations Material Types and Properties 8.2 Typical Damage and Failure Modes Walls Coupling ofmasonry Walls by Slabs, Beams or Masonry Spandrels 8.3 Design Process for Masonry Buildings

8 Contents xi Masonry Coupled Walls Response Design of Unreinforced Masonry Buildings Design of Reinforced Masonry Buildings D Response of Masonry Buildings Torsional Response Out-of-Plane Response ofwalls Timber Structures Introduction: Timber Properties Ductile Timber Structures for Seismic Response Ductile Moment-Resisting Connections in Frame Construction Timber Framing with Plywood Shear Panels Hybrid Prestressed Timber Frames DDBD Process for Timber Structures Capacity Design oftimber Structures Bridges Introduction: Special Characteristics of Bridges Pier Section Shapes The Choice between Single-column and Multi-column Piers Bearing-Supported vs. Monolithic Pier/Superstructure Connection Soil-Structure Interaction Influence ofabutment Design Influence ofmovementjoints Multi-Span Long Bridges P-~ Effects for Bridges Design Verification by Inelastic Time-History Analyses Review ofbasic DDBD Equations for Bridges Design Process for Longitudinal Response Pier Yield Displacement Design Displacement for Footing-Supported Piers Design Example 10.1: Design Displacement for a Footing-Supported Column Design Displacement for Pile/Columns Design Example 10.2: Design Displacement for a Pile/Column System Damping for Longitudinal Response Design Example 10.3: Longitudinal Design of a Four Span Bridge Design Process for Transverse Response Displacement Profiles Dual Seismic Load Paths System Damping 498

9 xii Priestley, Calvi and Kowalsky. Displacement-Based Seismic Design ofstmctures Design Example 10.4: Damping for the Bridge of Fig Degree offixity at Column Top Design Procedure Relative Importance oftransverse and Longitudinal Response Design Example 10.5: Transverse Design of a Four-Span Bridge Capacity Design Issues Capacity Design for Piers Capacity Design for Superstructures and Abutments Design Example 10.6: Design Verification of Design Example Structures with Isolation and Added Damping Fundamental Concepts Objectives and Motivations Bearing Systems, Isolation and Dissipation Devices Design Philosophy/Performance Criteria Problems with Force - Based Design ofisolated Structures Capacity Design Concepts Applied to Isolated Structures Alternative Forms ofartificiailsolation/dissipation Analysis and Safety Verification Bearing Systems, Isolation and Dissipation Devices Basic Types of Devices "Non-Seismic" Sliding Bearings Isolating Bearing Devices Dissipative systems Heat Problems Structural Rocking as a Form ofbase Isolation Displacement-Based Design ofisolated Structures Base-Isolated Rigid Structures Base-Isolated Flexible Structures Control1ed Response of Complex Structures Design Verification of Isolated Structures Design Example 11.7: Design Verification of Design Example Design Example 11.8: Design Verification of Design Example Wharves and Piers Introduction Structural Details The Design Process Factors Influencing Design Biaxial Excitation ofmarginal Wharves 603

10 Contents xiü Sequence of Design Operations Port of Los Angeles Performance Criteria POLA Earthquake Levels and Performance Criteria Performance Criteria for Prestressed Concrete Piles Performance Criteria for Seismic Design of Steel Pipe Piles Lateral Force-Displacement Response ofprestressed Piles Prestressed Pile Details Moment-Curvature Characteristics ofpile/deck Connection Moment-Curvature Characteristics of Prestressed Pile In-Ground Hinge Inelastic Static Analysis of a Fixed Head Pile Design Verification Eccentricity Inelastic Time History Analysis Capacity Design and Equilibrium Considerations General Capacity Design Requirements Shear Key Forces Design Example 12.1: Initial Design of a Two-Segment Marginal Wharf Aspects of Pier Response Disp1acement-Based Seismic Assessment 13.1 Introduction: Current Approaches Standard Force-Based Assessment Equivalent Elastic Strength Assessment Incremental Non-linear Time History Analysis 13.2 Displacement-Based Assessment of SDOF Structures Alternative Assessment Procedures Incorporation of P-~ Effects in Displacement-Based Assessment Assessment Example 13.1: Simple Bridge Column under Transverse Response 13.3 Displacement-Based Assessment of MDOF Structures Frame Buildings Assessment Example 2: Assessment of a Reinforced Concrete Frame Structural Wall Buildings Other Structures 14 Draft Disp1acement-Based Code for Seismic Design of Buildings References Symbols List

11 xiv Priestley, Calvi and Kowalsky. Displacement-Based Seismic Design of Structures Abbreviations 713 Index 715 Structural Analysis CD 721