Seismic Design of Steel Structures
Seismic Design of Steel Structures
Contents
1 Failure of a myth
1.1 The myth of steel as a perfect material
for seismic-resistant structures 1
1.1.1 Why steel is considered a perfect material 1
1.1.2 Seismic events justifying this myth 2
1.1.2.1 1906 San Francisco earthquake 2
1.1.2.2 1923 Kanto earthquake 3
1.1.2.3 1957 Mexico City earthquake 4
1.1.2.4 Is this myth justified? 6
1.1.3 Seismic decade 1985–1995: Failure of a myth 7
1.2 Behavior of steel structures during American and Asian earthquakes 8
1.2.1 1985 Mexico City earthquake (Mexico) 8
1.2.1.1 Earthquake characteristics 8
1.2.1.2 Soil conditions 8
1.2.1.3 Damage of some steel structures 11
1.2.1.4 Collapse of Pino Suarez buildings 11
1.2.2 1994 Northridge earthquake (USA) 18
1.2.2.1 Earthquake characteristics 18
1.2.2.2 Damage of connections 21
1.2.3 1995 Kobe earthquake (Japan) 24
1.2.3.1 Earthquake characteristics 24
1.2.3.2 Damage in some steel structures 27
1.2.3.3 Connection damage 28
1.2.4 1999 Kocaeli earthquake (Turkey) 37
1.2.4.1 Earthquake characteristics 37vi Contents
1.2.4.2 Steel structure damage 39
1.2.5 2003 Bam earthquake (Iran) 40
1.2.5.1 Earthquake characteristics 40
1.2.5.2 Steel structure damage 40
1.2.6 2010 Maule earthquake (Chile) 42
1.2.6.1 Earthquake characteristics 42
1.2.6.2 Steel structure damage 43
1.2.7 2011 Christchurch earthquake (New Zealand) 44
1.2.7.1 Earthquake characteristics 44
1.2.7.2 Steel structure damage 46
1.2.8 2011 Tohoku earthquake (Japan) 47
1.2.8.1 Earthquake characteristics 47
1.2.8.2 Steel structure damage 49
1.3 Behavior of steel structures during European earthquakes 51
1.3.1 General 51
1.3.2 1977 Vrancea earthquake (Romania) 52
1.3.2.1 Earthquake characteristics 52
1.3.2.2 Damage to one-story steel buildings 53
1.3.2.3 Damage to multistoried steel buildings 54
1.3.3 1999 Athens earthquake 55
1.3.3.1 Earthquake characteristics 55
1.3.3.2 Steel structure damage 56
1.3.4 2009 Abruzzo earthquake (Italy) 57
1.3.4.1 Earthquake characteristics 57
1.3.4.2 Steel structure damage 58
1.3.5 2012 Emilia earthquake (Italy) 58
1.3.5.1 Earthquake characteristics 58
1.3.5.2 Steel structure damage 59
1.4 Engineering lessons learned from the last strong earthquakes 62
1.4.1 Advances in structural design 62
1.4.2 Challenges in seismic design 66
2 Steel against earthquakes
2.1 Steel as the material of choice for seismic areas 73
2.2 Development of steel structural systems 76
2.2.1 Early development 76
2.2.2 Development in the United States 77Contents vii
2.2.3 Development in Asia 82
2.2.4 Development in Europe 88
3 Challenges in seismic design
3.1 Gap in seismic design methodologies 101
3.1.1 Seismic loading versus structural response 101
3.1.2 Critics of current design methodologies 102
3.1.3 Needs and challenges for the next design practice 105
3.2 Earthquake types 108
3.2.1 Plate tectonics 108
3.2.2 Factors influencing earthquakes 111
3.2.2.1 Source depth 111
3.2.2.2 Epicentral distance 111
3.2.2.3 Source types 112
3.2.3 World seismic zones 115
3.3 Strong seismic regions 118
3.3.1 Earthquake types in strong seismic regions 118
3.3.2 Structural problems for near-field earthquakes 121
3.3.2.1 Main characteristics of near-field earthquakes 121
3.3.2.2 Characteristics of structural responses 125
3.3.3 Structural problems for far-field earthquakes 129
3.3.3.1 Main characteristics of farfield earthquakes 129
3.3.3.2 Characteristics of structural responses 130
3.4 Low-to-moderate seismic regions 132
3.4.1 Earthquake types in low-to-moderate seismic regions 132
3.4.2 Low-to-moderate earthquakes in European seismic areas 135
3.4.3 Main characteristics of low-to-moderate ground motions 137
3.4.4 Structural design problems in the low to-moderate seismic regions 141
3.5 Proposals for improving the new code provisions 145
3.5.1 Two topics for new codes 145
3.5.2 Performance-based design 145
3.5.3 Influence of earthquake type 146
4 New generation of steel structures
4.1 Introduction 155
4.2 Improving existing solutions 157
4.2.1 Advanced eccentric-braced systems 157
4.2.2 Dog-bone systems 168
4.2.2.1 General concept 168
4.2.2.2 Dog-bone design 172
4.2.2.3 Experimental activity 174
4.2.2.4 Numerical activity 176
4.2.2.5 Further developments 182
4.2.3 Buckling-restrained-braced systems 183
4.2.3.1 Criticism to classical concentric braces (CBs) 183
4.2.3.2 BRB concept and details 184
4.2.3.3 Applications of BRBs in new and existing buildings 188
4.2.3.4 Seismic upgrading of existing RC buildings 191
4.3 New solutions of bracing systems 201
4.3.1 Shear wall systems 201
4.3.2 Behavior of metal shear panels 206
4.3.2.1 General concept 206
4.3.2.2 Theoretical issues 207
4.3.2.3 Shear panels modeling 210
4.3.3 Type of shear panels 214
4.3.3.1 Thin plates 214
4.3.3.2 Dissipative shear panels 218
4.3.3.3 Lightweight sandwich shear panels 224
4.3.4 Pure aluminum shear panels 236
4.3.4.1 General concept 236
4.3.4.2 Innovation by pure aluminum 237
4.3.4.3 Full bay-type shear panels 240
4.3.4.4 Bracing-type pure aluminum shear panels 244
4.3.5 Buckling inhibited shear panels: A new hysteretic damper typology 250
4.3.6 Retrofitting of existing RC structures 255
4.4 New solutions for connections 260
4.4.1 Introduction 260
4.4.2 PTED systems concept 260Contents ix
4.4.3 Studies on PTED systems: General framework 262
4.4.3.1 Technological solutions 262
4.4.3.2 Experimental studies 263
4.4.4 Numerical studies 268
5 Advances in steel beam ductility
5.1 New concepts on structural ductility 287
5.2 DUCTROT-M computer program 292
5.2.1 Investigation on local plastic mechanism models for beams 292
5.2.2 Characteristics of DUCTROT-M computer program 294
5.2.2.1 Modeling the member behavior 294
5.2.2.2 Computer performance 296
5.2.3 Local plastic mechanism for gradient moments 297
5.2.3.1 In-plane local plastic mechanism 297
5.2.3.2 Out-of-plane local plastic mechanism 306
5.2.3.3 Interaction between the in-plane and out-of-plane local plastic mechanisms 308
5.2.4 Local plastic mechanism for quasi-constant moments 309
5.2.5 Definition of ultimate rotation and rotation capacity 310
5.2.6 Validation of the DUCTROT-M computer program 312
5.3 Monotonic available ductility 313
5.3.1 Applications of the DUCTROT-M computer program 313
5.3.2 Cross-section ductility versus member ductility 315
5.3.3 Gradient versus quasi-constant moments 321
5.3.4 In-plane versus out-of-plane plastic mechanisms 323
5.3.5 Available rotation capacity of rolled beams 325
5.3.5.1 Influence of junction 325
5.3.5.2 Ductility of the RBS 328
5.3.5.3 Member ductility of the IPE and HEA beams 330
5.3.6 Available rotation capacity for welded beams 334
5.3.6.1 Influence of welding type 334x Contents
5.3.6.2 Influence of steel grade and yield stress random variability 335
5.3.6.3 Parametric studies on member rotation capacity 336
5.3.6.4 Suggestions for a proper selection of profile dimensions 339
5.3.7 Other applications of DUCTROT-M computer program 340
5.4 Local ductility under far-field earthquakes 343
5.4.1 Characteristics of far-field earthquakes 343
5.4.1.1 Crustal earthquakes (subduction or strike-slip types) 343
5.4.1.2 Subcrustal earthquakes 344
5.4.2 Ductility under cycle loading produced by far-field earthquakes 345
5.4.2.1 Shaking duration 345
5.4.2.2 Effective number of cycles of earthquake ground motions 346
5.4.2.3 Typology of cycle loading in function of earthquake type 347
5.4.2.4 Main effects of cycle loadings 350
5.4.3 Ultralow-cycle fatigue: A new opportunity to solve the dispute on cycle fatigue-accumulation of plastic deformations?
5.4.4 Cyclic actions on steel I-shaped beams 354
5.4.4.1 Review on experimental studies and theoretical approaches 354
5.4.4.2 Experimental testing 354
5.4.4.3 Theoretical approaches 358
5.4.4.4 Comments about experimental and theoretical results 360
5.4.5 Erosion of monotonic ductility due to accumulation of plastic deformations 362
5.4.5.1 Accumulation of plastic deformations 362
5.4.5.2 Example for bended plate under cyclic loading 362
5.4.5.3 Plastic collapse mechanism of I-shaped steel beams under cyclic loading 366
5.4.5.4 Local member plastic mechanism 369
5.4.6 Available beam ductility for far-field earthquakes 372Contents xi
5.4.6.1 The DUCTROT-M computer program for the prediction of available cyclic ductility by considering the affecting factors 372
5.4.6.2 Influence of loading type 373
5.4.6.3 Influence of cross-section shape 374
5.4.6.4 Influence of yield and ultimate stress ratio 375
5.4.6.5 Influence of yield strength 379
5.4.6.6 Influence of strength degradation 380
5.4.6.7 Classification of the cyclic available member ductility 381
5.5 Near-field earthquake effects on the available ductility of steel beams 383
5.5.1 Ductility problems for near-field earthquakes 383
5.5.2 Near-field earthquakes 385
5.5.2.1 General 385
5.5.2.2 Interplate crustal earthquakes 386
5.5.2.3 Intraplate crustal earthquakes 388
5.5.3 Phase 1: Wave propagation for P and S body waves 389
5.5.3.1 Ground motions on free sites or in the presence of buildings 389
5.5.3.2 Wave propagation approach 394
5.5.3.3 Applications in earthquake engineering 396
5.5.4 Phase 2: Effects of surface wave 399
5.5.4.1 Damage produced during the first phase due to the body P and S waves 399
5.5.4.2 Damage produced during the second phase due to the surface R and L waves 400
5.5.5 Influence of strain rate on available rotation ductility 401
5.5.5.1 Effects of strain rate on steel characteristics 401
5.5.5.2 Effects of strain rate on local ductility 406
5.5.6 Influence of strain rates on local fracture 407
5.5.6.1 Replacement of ductile rotation by local fracture due to strain rate 407
5.5.6.2 Fracture rotation of yield lines 410
5.5.6.3 Fracture of beam flanges 413xii Contents
5.5.6.4 Influence of strain rate on local fracture rotation 417
5.5.7 Another vision about the Northridge and Kobe damage 419
5.5.8 Fracture of welded MRF structures due to near-field earthquakes 421
5.5.8.1 P wave propagation 421
5.5.8.2 S wave propagation 424
5.5.8.3 Fracture of welded connections due to S wave propagation 425
5.5.8.4 Applications 429
6 Fire after earthquake
6.1 Introduction 441
6.2 Structural behavior under the effect of fire 443
6.3 Historical events to date 444
6.4 Postearthquake fire and risk management 449
6.4.1 General 449
6.4.2 Methodology 451
6.4.2.1 Building scale 451
6.4.2.2 Regional scale 451
6.4.3 Building-scale issues related to postearthquake fire 452
6.4.4 Regional-scale issues related to postearthquake fire 453
6.5 Computational aspects 454
6.5.1 General 454
6.5.2 Structural analyses 455
6.6 Analysis assumptions 456
6.6.1 Current codification approach 456
6.6.2 Structural and damage modeling 457
6.6.3 Fire modeling 460
6.7 Structural behavior 461
6.7.1 Single-story moment-resisting frame 461
6.7.2 Multistory moment-resisting frame 464
6.7.3 FEM models 468
6.8 Methodology for assessing robustness 478
6.8.1 General 4786.8.2 Case study and seismic performance characterization 480
6.9 Conclusive remarks 484
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