Earthquake Engineering, Application to Design

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Earthquake Engineering, Application to Design

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In view of the relatively large number of steel moment-resisting frames damaged during the Northridge earthquake, the book expands on the evaluation and performance of structures of this type. The pre- and post-Northridge experimental research and new design strategies to improve moment connections for new buildings are also discussed, keeping in mind basic building code concepts to demonstrate the application of general strength-level load combinations.

Topics relevant to seismic design in other areas of engineering, such as concrete, masonry, and wood-framed buildings, are also included. An attempt has been made to maintain a practical approach. In lieu of problem-solving, single design issues, the book walks the reader through step-by-step design of actual projects in moderate-to-high seismicity areas in compliance with building regulations.

Chapter 12 introduces a new method of dynamic analysis and discusses the causes of joint failure in steel design. Subjects like matrices, differential equations, numerical analysis, and engineering applications are presented for completeness and ready reference for the reader.

It is hoped that the book will help practicing engineers not yet fully familiar with seismic design and graduating students to use the building codes in their seismic design practice.

TOC

PREFACE xi
ACKNOWLEDGMENTS xiii
NOTATION xv
1 OVERVIEW 1
1.1 Introduction / 1
1.2 Concepts, Terminology, and Source of Earthquakes / 2
1.3 Wave Propagation and Velocities / 5
1.4 Magnitude of Earthquakes / 7
1.5 Building Damage / 7
1.6 Structural Failures: Overall Failure / 10
1.7 Component or Joint Failure / 17
1.8 Code Design Forces: Reserve Strength to Counter Extreme Forces / 21
2 SEISMIC DESIGN REGULATIONS 25
2.1 Building Codes / 25
2.2 UBC 1997: A Model Code / 26
2.3 Interaction of Building Codes and Other Standards / 27
2.4 IBC 2006 / 29
3 REINFORCED-CONCRETE STRUCTURES 36
3.1 Introduction / 36
3.2 Shearing Resistance of RC Beams / 40
3.3 Development Length / 45
3.4 Northridge Experience / 49
3.5 Case 1: Reinforced-Concrete Parking Garage / 50
3.6 Case 2: Reinforced-Concrete Retaining Wall System / 62
References / 67
4 SEISMIC STEEL DESIGN: SMRF 68
4.1 Design of SMRF Structure: LRFD Method / 68
4.2 Design Steps / 69
4.3 Project Description: Four-Story Office Building / 70
4.4 Project Layout and Typical SMRF per UBC 1994 / 70
4.5 1994 Design / 71
4.6 Wind Analysis: 1997 UBC, CHAPTER 16, DIV. III / 72
4.7 Example: Wind Analysis of Four-Story Building / 73
4.8 Seismic Zones 3 and 4 / 75
4.9 Earthquake Analysis of Four-Story Office Building / 76
4.10 Design for Earthquake / 79
4.11 Significant Changes in 1997 Design / 84
4.12 1997 versus 1994 Design / 86
4.13 Summary of Procedure / 87
4.14 Design Strategies / 89
4.15 Design of Beams: Code Requirements / 89
4.16 Second-Floor Beam / 91
4.17 Beam-to-Column Joint / 92
4.18 Flexural Resistance of Beam-to-Column Joint / 92
4.19 Shear Tab Design / 96
4.20 Shear Tab-to-Beam Welded Connection / 99
4.21 Second-Floor Panel Zone / 99
4.22 Third-Floor Beam / 102
4.23 Third-Floor Shear Tab Connection / 103
4.24 Third-Floor Beam-to-Column Moment Connection / 107
4.25 Third-Floor Panel Zone / 108
4.26 Design of Columns / 109
4.27 Column Final Design Data / 115
4.28 First-Story Column Design for Compression: Major Axis / 116
4.29 Column Design Flowchart / 120
4.30 Design of Third-Story Column for Compression / 120
4.31 Design of Third-Story Column Splice / 120
4.32 Reexamination of Pre- and Post-Northridge Research and Literature / 124
References / 126
5 SEISMIC STEEL DESIGN: BRACED FRAMES 128
5.1 Introduction / 128
5.2 Project Description: Four-Story Library Annex / 129
5.3 Wind Analysis / 129
5.4 Earthquake Analysis / 130
5.5 Wind and Earthquake Loads / 135
5.6 Response of Braced Frames to Cyclic Lateral Loads / 135
5.7 1997 UBC Provisions / 138
5.8 Rules Applicable to Bracing Members / 139
5.9 Column Strength Requirements / 141
5.10 Design for Earthquake / 141
5.11 Strategies for Brace Member Design / 142
5.12 Brace Members 2 and 3 / 144
5.13 Brace Members 3 and 2: First Story / 144
5.14 Design of Fillet Weld Connection / 148
5.15 Design of Gusset Plate: First and Second Stories / 149
5.16 Brace Member 13: Third Story / 152
5.17 Fillet Weld Design: Third and Fourth-Story Gusset Plates / 154
5.18 Gusset Plate Design: Third and Fourth Stories / 155
5.19 Vertical Component / 156
5.20 Column Design / 157
5.21 Column Splice Design: Third Floor / 166
5.22 Beam Design / 167
5.23 Column Base-Plate Design / 174
5.24 Summary of Design Procedures / 180
5.25 SEAOC Blue Book and the Code / 180
References / 182
6 IBC SEISMIC DESIGN OF SMRF STRUCTURES 184
6.1 IBC Setup of Seismic Design Forces / 184
6.2 Design Example / 184
6.3 IBC Building Categories / 187
7 MASONRY STRUCTURES 191
7.1 Introduction / 191
7.2 Case 1: Retaining Wall System / 193
7.3 Case 2: Seismic versus Wind / 206
7.4 Case 3: Design of CMU Wall and Precast Concrete Plate / 214
7.5 Case 4: Retail Store, Masonry and Steel / 217
References / 226
8 WOOD-FRAMED BUILDINGS 227
8.1 Introduction / 227
8.2 Northridge Lesson / 228
8.3 Case 1: Steel-Reinforced Wood-Framed Building / 237
8.4 Case 2: Wood-Framed Two-Story Home / 247
8.5 Case 3: Steel-Reinforced Two-Story Duplex / 252
8.6 Case 4: Wood-Framed Commercial Building / 256
8.7 Case 5: Wood-Framed Residential Building / 264
8.8 Case 6: Wood-Framed Garage and Workshop / 273
8.9 Light-Gauge Steel as Alternative to Wood Framing / 277
8.10 Case 7: Light-Gauge Steel in Multistory Project / 278
Appendix / 283
References / 289
9 MATRICES IN ENGINEERING 290
9.1 Use of Matrices in Engineering / 290
9.2 Matrix Addition and Multiplication / 292
9.3 Matrix Forms / 294
9.4 Transposition / 295
9.5 Minor and Cofactor Matrices / 295
9.6 Determinant of a Matrix / 296
9.7 Inverse of a Matrix / 297
9.8 Linear Systems of Equations / 298
9.9 Elementary Row Operations / 301
9.10 Summary of Matrix Operations / 302
10 DIFFERENTIAL EQUATIONS 303
10.1 Basic Concepts / 303
10.2 First-Order Differential Equations / 304
10.3 Separation of Variables / 304
10.4 Exact Equations / 305
10.5 Integrating Factor / 307
10.6 Second-Order Linear Equations / 309
10.7 Homogeneous Differential Equations / 313
10.8 Characteristic Equation / 313
11 NUMERICAL METHODS AND ENGINEERING APPLICATIONS 314
11.1 Introduction to Dynamic Analysis / 314
11.2 Equation of Motion / 315
11.3 Damping: Damped Free Vibration / 321
11.4 Free Vibrations: Two-Degree Systems / 323
11.5 Eigenvalues and Eigenvectors / 323
11.6 Modeling Actual Structures / 327
11.7 Three-Degree Systems / 329
11.8 Existence and Uniqueness Theory: Wronskian / 334
11.9 Driving Function (Ft): Seismic Ground Motion
as Ft / 334
12 METHODS AND TOOLS TO UNRAVEL SECRETS OF EARTHQUAKES 336
12.1 Elements of an Earthquake / 336
12.2 Vertical-Acceleration Component / 339
12.3 New Method of Dynamic Analysis / 339
12.4 Background of Research / 340
12.5 Analysis of Actual Structure / 342
12.6 Results and Findings / 344
12.7 Nature and Causes of Joint Failure / 344
References / 348
13 RECENT AND FUTURE DEVELOPMENTS IN SEISMIC
DESIGN 349
13.1 Tests on Joints / 349
13.2 Dogbone Experiment / 350
13.3 Joint Strain Hardening: Speed Straining / 350
13.4 Mechanism of Joint Degradation / 350
13.5 Conclusions / 351
13.6 New Trends / 352
13.7 Seismic Isolation / 353
13.8 Engineered Damping / 357
References / 358
ACRONYMS 359
GLOSSARY 361
References / 370
APPENDIX: COMPUTER ANALYSIS 371
A. SMRF Project Part I / 372
B. SMRF Project Part II / 388
C. Braced-Frame Project / 399
INDEX 423