Seismic Design of Steel Structures

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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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