Contents
Preface…………………………………………………………….xv
Author……………………………………………………………………………….xvii
Chapter 1 Design Criteria…………………………………………………………1
Classification of Buildings………………………………………………………………………………..1
Building Codes………………………………………………………………………………………………..1
Standard Unit Loads…………………………………………………………………………………………1
Tributary Area…………………………………………………………………………………………………1
Working Stress Design, Strength Design, and Unified Design of Structures……………6
Elastic and Plastic Designs………………………………………………………………………………..9
Elastic Moment Capacity……………………………………………………………………………. 10
Plastic Moment Capacity……………………………………………………………………………. 11
Combinations of Loads………………………………………………………………………………….. 13
Other Loads………………………………………………………………………………………………….. 14
Continuous Load Path for Structural Integrity………………………………………………….. 17
Problems………………………………………………………………………………………………………. 17
Chapter 2 Primary Loads: Dead Loads and Live Loads……………………23
Dead Loads…………………………………………………………………………………………………..23
Live Loads…………………………………………………………………………………………………….23
Floor Live Loads……………………………………………………………………………………………24
Basic Design Live Load, L0…………………………………………………………………………24
Effective Area Reduction Factor………………………………………………………………….25
Other Provisions for Floor Live Loads………………………………………………………………27
Roof Live Loads, Lr………………………………………………………………………………………..27
Tributary Area Reduction Factor, R1…………………………………………………………….28
Slope Reduction Factor……………………………………………………………………………….28
Problems……………………………………………………………………………………………………….28
Chapter 3 Snow Loads…………………………………. 31
Introduction………………………………………………………………………………………………….. 31
Minimum Snow Load for Low-Slope Roofs……………………………………………………… 31
Balanced Snow Load………………………………………………………………………………………34
Importance Factor……………………………………………………………………………………..34
Thermal Factor, Ct…………………………………………………………………………………….. 35
Exposure Factor, Ce…………………………………………………………………………………… 35
Roof Slope Factor, Cs…………………………………………………………………………………. 35
Rain-On-Snow Surcharge……………………………………………………………………………….36
Partial Loading of the Balanced Snow Load……………………………………………………..38
Unbalanced across the Ridge Snow Load………………………………………………………….38
Snow Drift from a Higher to a Lower Roof……………………………………………………….40
Leeward Snow Drift on Lower Roof of Attached Structure……………………………. 41
Windward Snow Drift on Lower Roof of Attached Structure…………………………. 42
Leeward Snow Drift on Lower Roof of Separated Structure…………………………… 42
Windward Snow Drift on Lower Roof of Separated Structure………………………… 43
Sliding Snow Load on Lower Roof………………………………………………………………….. 45
Sliding Snow Load on Separated Structures……………………………………………………… 47
Problems………………………………………………………………………………………………………. 47
Chapter 4 Wind Loads…………………………………………….. 51
Introduction………………………………………………………………………………………………….. 51
Definition of Terms……………………………………………………………………………………….. 51
Wind Hazard Maps……………………………………………………………………………………….. 52
Procedures for MWFRS………………………………………………………………………………… 52
Simplified Procedure for MWFRS for Low-Rise Buildings……………………………….. 52
Horizontal Pressure Zones for MWFRS………………………………………………………. 53
Vertical Pressure Zones for MWFRS………………………………………………………….. 62
Minimum Pressure for MWFRS…………………………………………………………………. 62
Procedures for Components and Cladding……………………………………………………….. 71
Simplified Procedure for Components and Cladding for Low-Rise Buildings………. 72
Minimum Pressures for C and C…………………………………………………………………. 72
Problems……………………………………………………………………………………………………….89
Chapter 5 Earthquake Loads………………………………………………… 91
Seismic Forces………………………………………………………………………………………………. 91
Seismic Design Procedures…………………………………………………………………………….. 91
Definitions…………………………………………………………………………………………………….92
Structural Height……………………………………………………………………………………….92
Stories above Base and Grade Plane…………………………………………………………….92
Fundamental Period of Structure…………………………………………………………………93
Site Classification………………………………………………………………………………………93
Seismic Ground Motion Values……………………………………………………………………….94
Mapped Acceleration Parameters…………………………………………………………………94
Risk-Targeted Maximum Considered Earthquake (MCER) Spectral
Response Acceleration Parameters………………………………………………………………94
Adjustments to Spectral Response Acceleration Parameters for Site Class
Effects………………95
Design Spectral Acceleration Parameters……………………………………………………..95
Design Response Spectrum…………………………………………………………………………95
Site-Specific Ground Motion Procedure…………………………………………………………. 104
Importance Factor, I…………………………………………………………………………………….. 105
Seismic Design Category……………………………………………………………………………… 105
Exemptions from Seismic Designs…………………………………………………………………. 106
Equivalent Lateral Force (ELF) Procedure to Determine Seismic Force……………. 106
Effective Weight of Structure, W……………………………………………………………….. 106
Seismic Response Coefficient, Cs………………………………………………………………. 106
Minimum Value of Cs………………………………………………………………………………. 107
Maximum SDS Value in Determining Cs…………………………………………………….. 107
Response Modification Factor or Coefficient, R 107
Distribution of Seismic Forces………………………………………………………………………. 108
Distribution of Seismic Forces on Vertical Wall Elements……………………………. 109
Distribution of Seismic Forces on Horizontal Elements (Diaphragms)…………… 110
Design Earthquake Load in Load Combinations……………………………………………… 110
Vertical Seismic Load Effect (Evertical)………………………………………………………… 111
Maximum SDS Value in Determining Evertical……………………………………………….. 111
Soil–Structure Interaction…………………………………………………………………………….. 115
Problems…………………………………………………………………………………………………….. 116
Chapter 6 Wood Specifications…………………………………………………………………………………….. 119
Engineering Properties and Design Requirements…………………………………………… 119
Format Conversion Factor, KF…………………………………………………………………… 120
Resistance Factor, ϕ………………………………………………………………………………… 120
Time Effect Factor, λ……………………………………………………………………………….. 121
Wet Service Factor, CM…………………………………………………………………………….. 121
Temperature Factor, Ct…………………………………………………………………………….. 121
Fire Retardant Treatment Factor……………………………………………………………….. 122
Design with Sawn Lumber……………………………………………………………………………. 122
More Factors Applicable to Lumber………………………………………………………………. 125
Incising Factor, Ci……………………………………………………………………………………. 125
Size Factor, CF………………………………………………………………………………………… 125
Size Factor, CF, for Dimension Lumber………………………………………………….. 125
Size Factor, CF, for Timber…………………………………………………………………… 125
Repetitive Member Factor, Cr……………………………………………………………………. 125
Flat Use Factor, Cfu………………………………………………………………………………….. 126
Buckling Stiffness Factor, CT……………………………………………………………………. 126
Bearing Area Factor, Cb…………………………………………………………………………… 126
LRFD Basis Lumber Design…………………………………………………………………………. 126
Structural Glued Laminated Timber………………………………………………………………. 130
Reference Design Values for GLULAM…………………………………………………………. 131
Adjustment Factors for GLULAM…………………………………………………………………. 132
Flat Use Factor for GLULAM, Cfu…………………………………………………………….. 132
Volume Factor for GLULAM, Cv………………………………………………………………. 132
Curvature Factor for GLULAM, Cc…………………………………………………………… 134
Stress Interaction Factor, CI………………………………………………………………………. 134
Shear Reduction Factor, Cvr………………………………………………………………………. 134
Structural Composite Lumber……………………………………………………………………….. 136
Adjustment Factors for Structural Composite Lumber……………………………………… 137
Repetitive Member Factor, Cr……………………………………………………………………….. 137
Volume Factor, Cv………………………………………………………………………………………… 137
Cross-Laminated Timber (CLT)……………………………………………………………………. 139
Effective Flexure Stiffness and Flexural Strength……………………………………………. 141
Effective Shear Strength Factor…………………………………………………………………….. 142
Effective Shear Stiffness………………………………………………………………………………. 143
Summary of Adjustment Factors……………………………………………………………………. 144
Problems…………………………………………………………………………………………………….. 146
Chapter 7 Flexure and Axially Loaded Wood Structures………………………………………………… 149
Introduction………………………………………………………………………………………………… 149
Design of Beams…………………………………………………………………………………………. 149
Bending Criteria of Design…………………………………………………………………………… 149
Beam Stability Factor, CL……………………………………………………………………………… 151
Effective Unbraced Length……………………………………………………………………….. 153
Shear Criteria……………………………………………………………………………………………… 154
Shear Strength of Sawn Lumber, GLULAM, and SCL…………………………………….. 155
Shear Strength of CLT……………………………………………………………………………… 155
Deflection Criteria……………………………………………………………………………………….. 156
Deflection of Sawn Lumber, GLULAM, and SCL…………………………………………… 156
Deflection of CLT………………………………………………………………………………………… 157
Creep Deflection………………………………………………………………………………………….. 159
Bearing at Supports……………………………………………………………………………………… 164
Bearing Area Factor, Cb…………………………………………………………………………… 164
Design of Axial Tension Members…………………………………………………………………. 166
Design of Columns………………………………………………………………………………………. 168
Column Stability Factor, CP………………………………………………………………………….. 169
Critical Buckling for Sawn Lumber, GLULAM, and SCL………………………………… 170
Critical Buckling for CLT…………………………………………………………………………….. 171
Design for Combined Bending and Compression…………………………………………….. 172
Problems…………………………………………………………………………………………………….. 177
Chapter 8 Wood Connections………………………………………………………………………………………. 183
Types of Connections and Fasteners………………………………………………………………. 183
Dowel-Type Fasteners (Nails, Screws, Bolts, Pins)…………………………………………… 183
Yield Limit Theory for Laterally Loaded Fasteners…………………………………………. 184
Yield Mechanisms and Yield Limit Equations………………………………………………… 185
Reference Design Values for Lateral Loads (Shear Connections)………………………. 187
Reference Design Values for Withdrawal Loads……………………………………………… 187
Adjustments of the Reference Design Values………………………………………………….. 187
Wet Service Factor, CM…………………………………………………………………………….. 187
Temperature Factor, Ct…………………………………………………………………………….. 187
Group Action Factor, Cg…………………………………………………………………………… 188
Geometry Factor, CΔ……………………………………………………………………………….. 188
End Grain Factor, Ceg………………………………………………………………………………. 191
Diaphragm Factor, Cdi……………………………………………………………………………… 191
Toenail Factor, Ctn…………………………………………………………………………………… 191
Nail and Screw Connections…………………………………………………………………………. 194
Common, Box, and Sinker Nails……………………………………………………………….. 194
Post-Frame Ring Shank Nails…………………………………………………………………… 194
Wood Screws………………………………………………………………………………………….. 195
Bolt and Lag Screw Connections…………………………………………………………………… 197
Bolts………………………………………………………………………………………………………. 197
Lag Screws…………………………………………………………………………………………….. 197
Problems…………………………………………………………………………………………………….. 199
Chapter 9 Tension Steel Members…………………………………………………………………………………203
Properties of Steel………………………………………………………………………………………..203
Provisions for Design Steel Structures…………………………………………………………….203
Unified Design Specifications………………………………………………………………………..204
Limit States of Design………………………………………………………………………………204
Design of Tension Members…………………………………………………………………………..205
Tensile Strength of Elements………………………………………………………………………….205
Net Area, An…………………………………………………………………………………………….206
Shear Lag Factor, U………………………………………………………………………………………208
Bolted Connection………………………………………………………………………………………..208
Welded Connection………………………………………………………………………………………209
For HSS Shapes…………………………………………………………………………………………… 210
Block Shear Strength……………………………………………………………………………………. 211
Design Procedure for Tension Members…………………………………………………………. 213
Problems…………………………………………………………………………………………………….. 215
Chapter 10 Compression Steel Members…………………………………………………………………………. 221
Strength of Compression Members or Columns………………………………………………. 221
Local Buckling Criteria…………………………………………………………………………………223
Flexural Buckling Criteria…………………………………………………………………………….224
Effective Length Factor for Slenderness Ratio…………………………………………………224
Limit States for Compression Design……………………………………………………………..227
Nonslender Members…………………………………………………………………………………….228
Flexural Buckling of Nonslender Members in Elastic and Inelastic Regions……228
Inelastic Buckling…………………………………………………………………………………….229
Elastic Buckling………………………………………………………………………………………229
Torsional and Flexural-Torsional Buckling of Nonslender Members………………229
Single-Angle Members…………………………………………………………………………………. 231
Built-Up Members……………………………………………………………………………………….. 231
Slender Compression Members……………………………………………………………………… 231
Effective Width of Slender Elements, be…………………………………………………………. 231
Use of the Compression Tables……………………………………………………………………… 232
Problems……………………………………………………………………………………………………..234
Chapter 11 Flexural Steel Members……………………………………………………………………………….. 241
Basis of Design……………………………………………………………………………………………. 241
Nominal Strength of Steel in Flexure…………………………………………………………….. 241
Lateral Unsupported Length…………………………………………………………………………. 241
Fully Plastic Zone with Adequate Lateral Support…………………………………………… 243
Inelastic Lateral Torsional Buckling Zone………………………………………………………. 243
Modification Factor Cb………………………………………………………………………………….244
Elastic Lateral Torsional Buckling Zone………………………………………………………….244
Noncompact and Slender Beam Sections for Flexure………………………………………..244
Compact Full Plastic Limit……………………………………………………………………………246
Noncompact Flange Local Buckling……………………………………………………………….246
Slender Flange Local Buckling………………………………………………………………………246
Summary of Beam Relations…………………………………………………………………………246
Design Aids…………………………………………………………………………………………………248
Shear Strength of Steel…………………………………………………………………………………. 251
Beam Deflection Limitations………………………………………………………………………… 252
Problems……………………………………………………………………………………………………..254
Chapter 12 Combined Forces on Steel Members……………………………………………………………… 257
Design Approach to Combined Forces…………………………………………………………… 257
Combination of Tensile and Flexure Forces…………………………………………………….. 258
Combination of Compression and Flexure Forces: The Beam-Column Members……..259
Members without Sidesway………………………………………………………………………. 259
Members with Sidesway……………………………………………………………………………260
Magnification Factor B1……………………………………………………………………………. 261
Moment Modification Factor, Cm………………………………………………………………. 261
K Values for Braced Frames………………………………………………………………………264
Braced Frame Design……………………………………………………………………………………264
Magnification Factor for Sway, B2…………………………………………………………………..268
K Values for Unbraced Frames………………………………………………………………………269
Unbraced Frame Design……………………………………………………………………………….. 270
Open-Web Steel Joists………………………………………………………………………………….. 274
Joist Girders…………………………………………………………………………………………………277
Problems…………………………………………………………………………………………………….. 278
Chapter 13 Steel Connections…………………………………………………………………………………………287
Types of Connections and Joints…………………………………………………………………….287
Bolted Connections………………………………………………………………………………………289
High-Strength Bolts………………………………………………………………………………….290
Types of Connections……………………………………………………………………………….290
Specifications for Spacing of Bolts and Edge Distance…………………………………….. 291
Bearing-Type Connections…………………………………………………………………………….292
Limit State of Shear Rupture…………………………………………………………………………293
Bearing and Tearout Limit State………………………………………………………………..294
Slip-Critical Connections………………………………………………………………………………296
Tensile Load on Bolts……………………………………………………………………………………299
Combined Shear and Tensile Forces on Bolts…………………………………………………..300
Combined Shear and Tension on Bearing-Type Connections…………………………300
Combined Shear and Tension on Slip-Critical Connections…………………………..303
Welded Connections……………………………………………………………………………………..304
Groove Welds………………………………………………………………………………………………305
Effective Area of Groove Weld………………………………………………………………….305
Fillet Welds………………………………………………………………………………………………….305
Effective Area of Fillet Weld……………………………………………………………………..305
Minimum Size of Fillet Weld…………………………………………………………………….306
Maximum Size of Fillet Weld……………………………………………………………………306
Length of Fillet Weld………………………………………………………………………………..306
Strength of Weld…………………………………………………………………………………………..306
CJP Groove Welds……………………………………………………………………………………306
PJP Welds and Fillet Welds……………………………………………………………………….306
Frame Connections……………………………………………………………………………………… 310
Shear or Simple Connection for Frames…………………………………………………………. 310
Single-Plate Shear Connection or Shear Tab………………………………………………. 310
Framed-Beam Connection………………………………………………………………………… 311
Seated-Beam Connection…………………………………………………………………………. 311
End-Plate Connection………………………………………………………………………………. 311
Single-Plate Shear Connection for Frames……………………………………………………… 312
Moment-Resisting Connection for Frames……………………………………………………… 315
Problems…………………………………………………………………………………………………….. 317
Chapter 14 Flexural Reinforced Concrete Members…………………………………………………………. 325
Properties of Reinforced Concrete…………………………………………………………………. 325
Compression Strength of Concrete………………………………………………………………… 325
Design Strength of Concrete…………………………………………………………………………. 326
Strength of Reinforcing Steel………………………………………………………………………… 327
Load Resistance Factor Design Basis of Concrete……………………………………………. 327
Reinforced Concrete Beams………………………………………………………………………….. 328
Derivation of the Beam Relations………………………………………………………………….. 328
Strain Diagram and Modes of Failure…………………………………………………………….. 330
Balanced and Recommended Steel Percentages………………………………………………. 331
Minimum Percentage of Steel……………………………………………………………………….. 331
Strength Reduction Factor for Concrete………………………………………………………….. 332
Specifications for Beams………………………………………………………………………………. 332
Analysis of Beams……………………………………………………………………………………….. 334
Design of Beams…………………………………………………………………………………………. 335
Design for Reinforcement Only………………………………………………………………… 335
Design of Beam Section and Reinforcement……………………………………………….. 337
One-Way Slab……………………………………………………………………………………………… 339
Specifications for Slabs…………………………………………………………………………………340
Analysis of One-Way Slab……………………………………………………………………………..340
Design of One-Way Slab………………………………………………………………………………. 341
Problems…………………………………………………………………………………………………….. 343
Chapter 15 Doubly and T-Shaped Reinforced Concrete Beams………………………………………….. 347
Doubly Reinforced Concrete Beams………………………………………………………………. 347
Analysis of Doubly Reinforced Beams……………………………………………………………349
Design of Doubly Reinforced Beams……………………………………………………………… 352
Monolithic Slab and Beam (T-Beams)……………………………………………………………. 354
Analysis of T-Beams……………………………………………………………………………………. 355
Design of T-Beams………………………………………………………………………………………. 357
Problems……………………………………………………………………………………………………..360
Chapter 16 Shear and Torsion in Reinforced Concrete………………………………………………………365
Stress Distribution in Beam…………………………………………………………………………..365
Diagonal Cracking of Concrete……………………………………………………………………… 367
Strength of Web (Shear) Reinforced Beam………………………………………………………368
Shear Contribution of Concrete………………………………………………………………………369
Shear Contribution of Web Reinforcement………………………………………………………369
Specifications for Web (Shear) Reinforcement………………………………………………… 370
Analysis for Shear Capacity………………………………………………………………………….. 372
Design for Shear Capacity…………………………………………………………………………….. 373
Torsion in Concrete……………………………………………………………………………………… 376
Provision for Torsional Reinforcement…………………………………………………………… 378
Problems……………………………………………………………………………………………………..380
Chapter 17 Compression and Combined Forces Reinforced Concrete Members………………….. 387
Types of Columns………………………………………………………………………………………… 387
Pedestals…………………………………………………………………………………………………387
Columns with Axial Loads………………………………………………………………………. 387
Short Columns with Combined Loads……………………………………………………….. 387
Large or Slender Columns with Combined Loads……………………………………….. 387
Axially Loaded Columns……………………………………………………………………………… 388
Strength of Spirals……………………………………………………………………………………….. 389
Specifications for Columns……………………………………………………………………………390
Analysis of Axially Loaded Columns…………………………………………………………….. 391
Design of Axially Loaded Columns………………………………………………………………. 393
Short Columns with Combined Loads……………………………………………………………. 396
Effects of Moment on Short Columns……………………………………………………………..397
Case 1: Only Axial Load Acting………………………………………………………………..397
Case 2: Large Axial Load and Small Moment (Small Eccentricity)………………. 398
Case 3: Large Axial Load and Moment Larger than Case 2 Section………………. 398
Case 4: Large Axial Load and Moment Larger than Case 3 Section………………. 398
Case 5: Balanced Axial Load and Moment………………………………………………….399
Case 6: Small Axial Load and Large Moment……………………………………………..399
Case 7: No Appreciable Axial Load and Large Moment……………………………….399
Characteristics of the Interaction Diagram……………………………………………………… 401
Application of the Interaction Diagram………………………………………………………….. 401
Analysis of Short Columns for Combined Loading…………………………………………..402
Design of Short Columns for Combined Loading…………………………………………….403
Long or Slender Columns………………………………………………………………………………405
Problems……………………………………………………………………………………………………..405
Chapter 18 Pre-Stressed Concrete Structures………………….409
Pre-Stressing of Concrete………………………………………………………………………………409
Pre-Tensioning…………………………………………………………………………………………409
Post-Tensioning………………………………………………………………………………………..409
Stressing and Anchorage Devices……………………………………………………………… 411
Pre-Tensioning versus Post-Tensioning………………………………………………………. 411
Materials for Pre-Stressed Concrete………………………………………………………………. 411
High-Strength Steel…………………………………………………………………………………. 411
Allowable Stress in Pre-Stressed Steel……………………………………………………….. 412
High-Strength Concrete……………………………………………………………………………. 412
Shrinkage of Concrete……………………………………………………………………………… 413
Creep of Concrete……………………………………………………………………………………. 413
Allowable Stress in Concrete……………………………………………………………………. 414
Pre-Stress Losses…………………………………………………………………………………………. 415
Loss Due to Elastic Shortening (ES)………………………………………………………….. 415
Loss Due to Shrinkage (SH) of Concrete……………………………………………………. 416
Loss Due to Creep (CR) of Concrete………………………………………………………….. 417
Loss Due to Relaxation (RE) of Steel………………………………………………………… 417
Loss Due to Friction (FL)…………………………………………………………………………. 418
Total Losses of Stress…………………………………………………………………………………… 419
Analysis of Stresses during Pre-Stressing……………………………………………………….. 419
Tendon with Eccentricity……………………………………………………………………………… 419
Stresses at Transfer………………………………………………………………………………….. 420
Stresses at Service Load…………………………………………………………………………… 420
Ultimate Limit State Design…………………………………………………………………………. 426
Cracking Moment………………………………………………………………………………………… 426
Strains at Different Stages of Loading……………………………………………………………. 427
Stage 1: At Transfer…………………………………………………………………………………. 427
Stage 2: After Application of External Load………………………………………………. 427
Stresses and Forces after Application of the Load……………………………………………. 428
Ultimate Moment Capacity…………………………………………………………………………… 429
Maximum and Minimum Reinforcement…………………………………………………… 429
Ultimate Shear Strength Design…………………………………………………………………….. 430
Shear Strength Provided by Concrete…………………………………………………………….. 431
Shear Capacity of Cracked Section (Flexure Induced Shearing)……………………. 431
Shear Capacity of Uncracked Section (Web-Shear Cracking)……………………….. 432
Shear Strength Provided by Web Reinforcement……………………………………………… 433
Problems…………………………………………………………………………………………………….. 434
Chapter 19 Application of Simulations in Structural Design………………… 437
Aaron Trisler, MS, Technical Account Manager, and Ashwini Kumar, PhD,
Principal Engineer
Introduction………………………………………………………………………………………………… 437
Analyzing a Simple Beam Using Analytical Method……………………………………….. 438
Mathematical Modeling Technique……………………………………………………………….. 439
Mathematical Modeling of Beam with Sign Board…………………………………………..440
Model Setup and Input……………………………………………………………………………..440
Model Output………………………………………………………………………………………………442
Solution and Post-Processing…………………………………………………………………….442
Exploring Model Output for “What If?”………………………………………………………….444
Mathematical Modeling of a Staircase……………………………………………………………444
What If?………………………………………………………………………………………………….445
Real-Life Structural Engineering Problems……………………………………………………..445
Accessing ANSYS for Students……………………………………………………………………..446
Summary…………………………………………………………………………………………………….446
Appendix A: General…………………………………….447
Appendix B: Wood…………………………………………. 453
Appendix C: Steel…………………………………………………………….. 515
Appendix D: Concrete…………………………………………………………….. 567
Bibliography………………………………………………. 589
Index……………………………………………………….. 593