EARTHQUAKE PLANNING SCENARIO: SAN DIEGO–TIJUANA AREA
1 INTRODUCTION 1 11 Goals of Performance-Based Seismic Design 1 12 Enhanced Seismic Performance through Base Isolation 3 13 Objectives of Research 4 14 Organization of Report 5 2 REVIEW OF SEISMIC ISOLATION 7 21 The Concept of Seismic Isolation 7 22 Current Status of Seismic Isolation 8 221 Evolution of Code Provisions for Seismically Isolated Buildings 10 23 Categories of Isolation Devices 12 231 Elastomeric Bearings 12 232 Sliding Bearings 13 24 Supplemental Dampers to Control Isolator Deformation 14 25 Previous Research on Seismic Isolation 15 251 Elastomeric Isolation Systems 15 252 Sliding Isolation Systems 16 253 Behavior of Secondary Systems 17 2531 Nonstructural Component and Content Damage 17 2532 Protection of Secondary Systems through Seismic Isolation 18 3 MULTI-STAGE FRICTION PENDULUM BEARINGS 21 31 Single-Pendulum Bearings 21 32 Double Pendulum Bearings 25 33 Triple Pendulum Bearings 29 331 Stages of Lateral Displacement 32 332 Construction of a Force-Displacement Relation 38 333 The Suitability of Small-Deformation Theory 42 334 Development of Cyclic Model 44 3341 Model Componentss 45 3342 Equilibrium Conditions 45 3343 Compatibility Conditions 45 3344 Constitutive Relations 46 3345 Force-Based Hysteretic Model 47 3346 Selection of Cyclic Series Model Parameters 49 4 EXPERIMENTAL PROGRAM 55 41 Description of Test Facility 56 42 Experimental Specimen 57 421 Supported Model Structure 57 422 Model Friction Pendulum Bearings 61 423 Double Pendulum Bearings 61 424 Triple Pendulum Bearings 63 425 Attachments 65 43 Data Acquisition and Instrumentation 66 44 Harmonic Characterization Tests 68 45 Earthquake Simulation Tests 71 451 Selection of Ground-Motion Recordings 71 452 Scaling of Records for Simulation 72 46 Summary of Shake Table Test Sequence 75 5 EXPERIMENTAL RESULTS 93 51 Cyclic Characterization of Isolator Behavior 93 511 Double Pendulum Bearings 94 512 Triple Pendulum Bearing 97 52 Comparison of Observed Behavior with Cyclic Model of the Triple Pendulum Bearing 115 521 Stage I Sliding 115 522 Stage II Sliding 117 523 Stage III Sliding 119 524 Stage IV Sliding 120 53 Seismic Response of Isolation Systems 121 531 Unidirectional Ground Motion 121 532 Effect of Vertical Ground Motion on Cyclic Behavior of Isolators 126 533 Effect of Tridirectional Ground Motion on Cyclic Behavior of Isolators 129 54 Seismic Response of Supported Structure 132 541 System Identification of Steel Superstructure 132 542 Interstory Drifts 134 543 Floor Accelerations 134 55 Conclusions 138 6 ANALYTICAL SIMULATIONS 147 61 Introduction 147 62 The Role of Interstory Drift and Floor Acceleration in Seismic Performance of Structures 148 63 Parametric Studies of Two-Degree-of-Freedom Systems 149 631 Effect of Nonlinear Damping Elements 151 632 Effect of Linear Viscous Energy Dissipation on Seismic Performance 159 633 Effect of Bilinear Hysteretic Energy Dissipation on Seismic Performance 171 634 Effect of Triple Pendulum Bearings on Seismic Performance 179 64 Seismic Response of Multi-story Isolated Structures 185 641 Ground-Motion Selection 185 642 Methodology for System Parameter Selection 188 643 Parametric Studies 192 644 Analytical Results 195 65 Conclusions 219 7 PERFORMANCE-BASED SEISMIC DESIGN METHODOLOGY FOR BASE ISOLATED STRUCTURES 229 71 Introduction 229 72 Probabilistic Assessment of Seismic Performance 230 721 Multivariate Probability Density 232 722 Estimation of Demand Parameter Distribution 233 723 Computation of Failure Probability 239 73 Applications to Performance-based Earthquake Engineering 240 731 A Multiple-Objective Seismic Performance Classification 241 732 Treatment of Performance Objectives in Building Codes 242 733 Establishment of Limit State Vectors 244 734 Definition of Seismic Performance Classifications 248 74 Reliability Analysis of Seismic Isolation Systems 249 741 Probabilistic Seismic Hazard Analysis 250 742 Probabilistic Seismic Demand Analysis 252 743 Reliability-Based Seismic Performance Classification 271 75 Conclusions 275 8 CONCLUSIONS AND RECOMMENDATIONS 279 81 Summary and Conclusions of Research Program 279 811 Multi-Stage Friction Pendulum Bearings 279 812 Analytical Simulations 281 813 Performance Assessment 282 82 Recommendations for Further Research 283 821 Triple Pendulum Model 283 822 Analytical Simulations 284 823 Performance Assessment 284 REFERENCES 287