Seismic Risk Assessment and Retrofitting (eBook)

Foreword 5
Preface 7
Contents 9
Contributors 11
1 Seismic Monitoring to Assess Performance of Structures in Near-Real Time: Recent Progress 14
1.1 Introduction 15
1.1.1 Background and Rationale 15
1.1.2 Requisites 16
1.2 Two Approaches for Measuring Displacements 16
1.2.1 Use of GPS for Direct Measurements of Displacements 17
1.2.1.1 Early Pioneering Application of GPS 17
1.2.1.2 Recent Developments with Higher Sampling Rate GPS 19
1.2.2 Displacement via Real-Time Double Integration 20
1.3 Monitoring Single Structure vs. Campus Structures 24
1.4 Conclusions 24
Appendix: Review of Seismic Monitoring Issues 26
Introduction 26
Historical Perspective 27
General Instrumentation Issues 28
Data Utilization 28
Code Versus Extensive Instrumentation 28
Associated Free-Field Instrumentation 30
Record Synchronization Requirement 31
Recording Systems, Constraints and New Developments 31
References 33
Soil-Structure Interaction Array(s) 32
2 Dance for Modern Times: Insurance, Economic Stability and Building Strength 38
2.1 Preparing the Stage 38
2.2 Government Schemes Insurance 39
2.3 Building Strength 41
2.4 CAT Models Do You Want To Dance? 42
2.5 Lets Dance The TCIP 45
2.6 Conclusion 48
References 49
3 A Critical Review of Current Assessment Procedures 51
3.1 Introduction 51
3.2 The SPEAR Project: Framework, Motivation, Methods 55
3.3 The SPEAR Structure 56
3.4 Assessment Exercise: Introductory Remarks 58
3.4.1 Prescriptions and Methods 59
3.4.1.1 FEMA 356 59
3.4.1.2 New Zealand Assessment Guidelines (2000 and 2002) 59
3.4.1.3 Japanese Guidelines 60
3.4.1.4 EC8 Part 3 (Draft 2001) 60
3.4.2 Implementation and Outcomes 62
3.4.2.1 FEMA and New Zealand Outcomes 62
3.4.2.2 Japanese Guidelines and EC8 Procedures Outcomes 66
3.4.3 Comparison between the Experimental Results and the Assessment Outcomes 69
3.4.3.1 Maximum Displacements 69
3.4.3.2 Column Drifts 71
3.4.3.3 Concluding Remarks 76
3.4.4 Further Developments and Recent Advancements 77
3.4.4.1 FEMA 440 and ATC58 78
3.4.4.2 EC8 Part 3 (2006) 79
References 80
4 Risk Management and a Rapid Scoring Technique for Collapse Vulnerability of RC Buildings 82
4.1 Introduction 82
4.2 Need for Mitigation Strategies at National Level 83
4.2.1 Education and Research 83
4.2.2 Seismic Network 85
4.2.3 Inventory of Buildings and Data Collection 85
4.2.4 Supervision of New Constructions 86
4.2.5 Earthquake Damage Indemnity -- The Old System 87
4.2.6 Earthquake Damage Indemnity -- The DASK System 89
4.3 The Zero Loss of Life Project 90
4.4 P25 Rapid Scoring Technique 91
4.4.1 Calculation of the Basic Score, P 1 92
4.4.2 Short Column Score, P2 94
4.4.3 Soft-Weak Storey Score, P3 95
4.4.4 Frame Discontinuity Score, P4 95
4.4.5 Pounding Failure Score, P5 96
4.4.6 Soil Failure Scores, P6 and P7 96
4.5 Final Score in the P25 Method 96
4.6 Conclusions 98
References 99
5 The Importance of Plan-Wise Irregularity 101
5.1 Introduction 101
5.2 The SPEAR Project: Framework, Motivation, Methods 102
5.3 The SPEAR Structure 104
5.4 Critical Review of the Experimental Results 106
5.4.1 As-Built Configuration 106
5.4.2 Torsional Issues vs Other Critical Issues 107
5.5 Retrofitting Strategies: Conceptual Design 108
5.5.1 FRP-Retrofitted Configuration 109
5.5.2 RC-Jacketed Configuration 110
5.6 Retrofitting Strategies: Comparative Critical Review of the Experimental Results 111
5.6.1 FRP-Retrofitted Configuration 111
5.6.2 RC-Jacketed Structure 113
5.7 Critical Evaluation of the Performance of the Interventions 115
5.8 Criteria for the Design of Retrofitting in Plan-Wise Irregular Structures 118
References 120
6 Advanced Composite Materials and Steel Retrofitting Techniques for Seismic Strengthening of Low-Rise Structures: Review 121
6.1 Introduction 121
6.2 Causes of Collapse 123
6.3 FRP Retrofitting Techniques for Collapse Prevention 125
6.3.1 Strengthening Columns 125
6.3.2 Column-Beam Joints 125
6.3.3 Concrete Columns Confined with Hybrid Composite Materials 128
6.3.4 Masonry Walls 129
6.3.5 Near Surface Mounted Reinforcement Technique 131
6.4 Steel Retrofitting Techniques Used to Prevent Collapse 132
6.4.1 Columns Retrofitted with Steel 132
6.4.2 Existing Frame Retrofitted with Steel Strips 132
6.4.3 URM Retrofitting with Steel 132
6.4.4 Energy Dissipation Devices and Damage Control Structure 133
6.5 Conclusions 134
References 135
7 A Novel Structural Assessment Technique to Prevent Damaged FRP-Wrapped Concrete Bridge Piers from Collapse 137
7.1 Introduction 137
7.2 Failure Mechanisms of FRP-Wrapped Concrete Systems 139
7.3 Structural Assessment Technique Far-Field Airborne Radar NDT 140
7.3.1 Review of Current NDT Techniques 140
7.3.1.1 Acoustic and Ultrasound NDT 140
7.3.1.2 Thermal NDT 140
7.3.1.3 Radiography NDT 140
7.3.1.4 Radar/Microwave NDT 141
7.3.2 Overview of the FAR NDT Technique 142
7.3.3 Specimen Description and Experimental Measurement 143
7.3.4 Progressive Image Focusing 144
7.3.5 Image Reconstruction for Structural Assessment 145
7.3.5.1 Damage Detection 145
7.3.5.2 Effectiveness of Incident Angle 147
7.3.5.3 Effects of Bandwidth and Center Frequency 147
7.4 Conclusions 149
References 150
8 Strengthening of Low-Rise Concrete Buildings:Applications After Dinar (1995) and Adana-Ceyhan (1998) Earthquakes 152
8.1 Introduction 152
8.2 Turkish Seismic Code Provisions for Masonry Buildings 153
8.3 Low-Rise Buildings: Masonry vs. Reinforced Concrete Frame Buildings? 155
8.4 The Dinar (1995) and the Adana-Ceyhan (1998) Earthquakes 156
8.5 Damage in Low-Rise Buildings 157
8.6 Post-Earthquake Evaluation of Damaged Low-Rise Buildings 160
8.7 Strength Evaluation of Low-Rise Buildings 166
8.8 Techniques for the Repair and Upgrading of Damaged Low-Rise Buildings 167
8.9 Application Details 175
8.10 Conclusions 177
References 177
9 Rehabilitation of Precast Industrial Buildings using Cables to Develop Diaphragm Action 178
9.1 Introduction 178
9.2 Prototype Building 181
9.3 Ground Motions 182
9.4 Overview of Rehabilitation Scheme 183
9.5 Analytical Models 187
9.6 Seismic Response of Rehabilitated Building 188
9.7 Strengthening of Connections 189
9.7.1 Interior Connections 191
9.7.2 Exterior Connections 193
9.8 Summary and Conclusions 194
References 196
10 Vulnerability Evaluation and Retrofitting of Existing Building Heritage: an Italian Research Programme 197
10.1 Introduction 197
10.2 Seismic Danger 198
10.3 New Design Code 200
10.4 Seismic Vulnerability 201
10.5 Previous Researches 202
10.5.1 Assobeton 1 203
10.5.2 Assobeton 2 206
10.5.3 Ecoleader 207
10.5.4 Growth 209
10.5.5 Precast Structures 210
10.5.6 Connections 213
References 217
11 Soft-Landing Base-Isolation System 219
11.1 Introduction 219
11.2 Outline of the Soft-Landing Base-Isolation System 220
11.3 Shaking Table Test 222
11.4 Failure Mode Control of Existing Column 223
11.4.1 Necessity of Controlling the Failure Mode of Existing Columns 223
11.4.2 Test Specimens 225
11.4.3 Loading 228
11.4.4 Test Results 228
11.4.5 Strength 229
11.4.6 Axial Load Carrying Capacity 230
11.5 Existing and New Column Connection 232
11.5.1 Specimens 232
11.5.2 Capacity of the Connections 234
11.5.3 Loading and Measuring System 237
11.5.4 Experimental Test Results 237
11.5.4.1 Vertical Load Carrying Capacity 237
11.5.4.2 Lateral Load-Relative Rotational Angle Relationship 239
11.5.4.3 Relationship between Vertical and Lateral Load Carrying Capacity 239
11.6 Concluding Remarks 242
11.7 Future Studies 242
Reference 243
12 Development of a New Precast Concrete Panel Wall System Incorporated with Energy Dissipative Dowel Connectors 244
12.1 Introduction 244
12.2 Cyclic Panel Tests 245
12.2.1 Test Parameters 246
12.2.2 Loading History 247
12.2.3 Loading Frame Setup 248
12.2.4 Measurement System 249
12.3 Test Results: Measured Force-Displacement Plots 249
12.3.1 Comparison About the Cyclic Envelope and Remarks 251
12.3.2 Calculated Response Energy by the Connectors 253
12.4 Failure Criteria for Connectors 255
12.5 Simplified Tri-Linear Curves for Connectors 260
12.6 Quantifying the Effects of Connectors on Building Response 263
12.6.1 Supplementary Equivalent Viscous Damping by the Connectors 263
12.6.2 Resistance Contribution by the Connectors 270
12.7 Concluding Remarks 272
13 Alternative Performance-Based Retrofit Strategies and Solutions for Existing RC Buildings 274
13.1 Introduction 274
13.2 Moving Towards a Performance-Based Retrofit Approach 276
13.3 Seismic Vulnerability Assessment Phase: The Fundamental and Delicate Role of an Appropriate Diagnosis 278
13.3.1 Understanding the Weaknesses of Beam-Column Joints: The Devil is in the Details 279
13.3.2 Hierarchy of Strength and Sequence of Events: A Dangerous Equivalence 281
13.3.2.1 Importance of Accounting for the Variation of Axial Load 282
13.3.3 Effects of Bi-Directional Cyclic Loading 283
13.3.4 The Controversial Effects of Masonry Infills on the Seismic Response: An Open Debate 286
13.4 Multi-Level Retrofit Strategy: A Rational Compromise with the Reality 286
13.4.1 Implementation of a Multi-Level Retrofit Strategy using Alternative Solutions 288
13.5 Suggestions for Advanced Retrofit Solutions 291
13.5.1 Emerging Trends in Low-Damage Seismic Resisting Systems 291
13.5.2 Use of Precast Post-Tensioned Rocking/Dissipative Shear Walls 292
13.5.2.1 Selective Weakening as a Basis for Seismic Retrofit 293
13.6 Remembering the Bigger Picture: Seismic Risk Analysis and Management as a Decision-Making Tool for the Retrofit Intervention at Territorial Scale 296
13.7 Conclusive Remarks: Time for Some Action 299
References 300
14 FRP Wrapping of RC Structures Submitted to Seismic Loads 303
14.1 Introduction 303
14.2 Experimental Program 304
14.3 Performance Based vs. Conventional Confinement 305
14.4 Test Results 307
14.5 Conclusion 310
References 311
15 Upgrading of Resistance and Cyclic Deformation Capacity of Deficient Concrete Columns 312
15.1 Introduction 312
15.2 RC-Jacketing of Columns 313
15.2.1 Strength, Stiffness and Deformation Capacity of Monolithic Concrete Members with Continuous Reinforcement 313
15.2.2 Simple Rules for the Strength, the Stiffness and the Deformation Capacity of Jacketed Members 317
15.3 FRP-Jacketing of Columns 322
15.3.1 Seismic Retrofitting with FRPs 322
15.3.2 FRP-Wrapped Columns with Continuous Vertical Bars 322
15.3.2.1 Yield Moment and Effective Stiffness to Yield Point 322
15.3.2.2 Flexure-Controlled Deformation Capacity 326
15.3.3 FRP-Wrapped Columns with Ribbed (Deformed) Vertical Bars Lap-Spliced in the Plastic Hinge Region 329
15.3.4 Cyclic Shear Resistance of FRP-Wrapped Columns 332
References 333
16 Supplemental Vertical Support as a Means for Seismic Retrofit of Buildings 334
16.1 Introduction and Background 334
16.2 Conceptual Procedure and Background 337
16.2.1 Horizontal and Vertical Load Characteristics of Weak Story Components 337
16.2.2 System Capacity Boundary (Pushover) 339
16.2.3 Simplified Dynamic Analysis 339
16.2.4 Collapse Mode Risks 341
16.3 Example Application 342
16.4 Summary and Conclusions 346
References 347
17 How to Predict the Probability of Collapse of Non-Ductile Building Structures 348
17.1 Introduction 348
17.2 Strength and Stiffness Deterioration 349
17.2.1 Modes of Deterioration Observed from Experiments 349
17.2.2 Analytical Modeling of Deterioration 351
17.3 Assessment of Collapse 353
17.3.1 Effect of Deterioration on Assessment of Collapse 354
17.3.2 Methods for Assessing the Probability of Collapse 355
17.4 Experimental Observations Frames with Infill Walls 357
17.5 Parameter Study Employing Deteriorating SDOF Systems 360
17.5.1 Ground Motions 360
17.5.2 Parameters of Structural Models 360
17.5.3 Response -- Examples 362
17.5.4 Collapse Fragility Curves 364
17.5.5 Evaluation of Median (and 10-percentile) Collapse Capacity 365
17.6 Concluding Remarks 368
References 369
18 Strengthening of Brick Infilled Reinforced Concrete (RC) Frames with Carbon Fiber Reinforced Polymers (CFRP) Sheets 371
18.1 Introduction 371
18.2 Test Program 372
18.2.1 Test Specimens and Materials 372
18.2.2 Test Setup and Instrumentation 375
18.2.3 Behavior of the Test Specimens 376
18.2.3.1 Series-L Tests 376
18.2.3.2 Series-N Tests 380
18.3 Discussion of Test Results 382
18.4 Conclusions 388
References 389
19 Improved Infill Walls and Rehabilitation of Existing Low-Rise Buildings 391
19.1 Introduction 391
19.2 Common Deficiencies and Material Characteristics 393
19.3 Experimental Works 395
19.3.1 First Stage Experiments 395
19.3.2 Second Stage Experiments 399
19.3.3 Third Stage Experiments 408
19.3.4 Experimentally Obtained Damping Ratios and Earthquake Load Reduction Factors 408
19.3.4.1 Damping Ratios 408
19.3.4.2 Earthquake Load Reduction Factors 411
19.4 Hypothetical Building 414
19.5 The Proposed Rehabilitation Technique 421
19.6 Hypothetical Example 423
19.7 Conclusions 424
19.8 Appendix: Mathematical Model of the Retrofitted Infill Wall 426
References 428
20 How to Simulate Column Collapse and Removal in As-built and Retrofitted Building Structures? 431
20.1 Introduction 431
20.2 Direct Element Removal 433
20.3 Element Removal Criteria 436
20.3.1 RC Columns in Flexure-Axial Collapse 436
20.3.2 RC Columns in Shear-Axial Collapse 437
20.3.3 Truss Elements 437
20.4 Deficient and Retrofitted Component Models 438
20.4.1 Confined RC Cross-Section Model 438
20.4.2 Confined Concrete Material Model 441
20.4.2.1 Behavior in Compression 441
20.4.2.2 Stress Reduction, Damage Index, and Experimental Calibration 443
20.4.2.3 Behavior in Tension 444
20.4.3 Buckling-Enabled Longitudinal Steel Material Model 445
20.4.3.1 Detecting the Onset of Buckling 445
20.4.3.2 Monotonic Post-Buckling Behavior 446
20.4.3.3 Hysteretic Post-Buckling Behavior 448
20.4.3.4 Stress Reduction, Damage Index, and Experimental Calibration 449
20.4.4 Deficient Lap Splice Material Model 450
20.4.4.1 Stress Reduction, Damage Index, and Experimental Calibration 452
20.5 Applications of Damage and Collapse Identification 452
20.6 Concluding Remarks 454
References 455
Color Plates 457
Index 485