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INDEX Acceleration, 6 angular, 4 in building codes, 232, 233, 235, 238 constant acceleration method, 124, 129 d’Alembert’s principle, 9 dynamic nonlinear analysis, 187 earthquake ground motion, 18, 19 earthquake response in SDOF systems, 212, 213 elastic design response, 210 Holzer method, 159 linear acceleration method, 124, 127 linear elastic response, 203–206 measuring, 96 Newmark’s numerical method, 127 numerical integration methods, 124–127 and resonance, 87 seismic response analysis, 179 spectral analysis, 225 time-dependent force, 15–17, 24 undamped free vibration, 51 Amendments (building codes), 261 American Society of Civil Engineers (ASCE), 251 Amplitude: defined, 54 half-power, 92 Angular acceleration, 4 Angular momentum, 3, 4 Applied load, in static vs. dynamic problems, 9 Applied Technology Council (ATC), 256 Applied Technology Council (ATC) 3–06 resource document for model codes (1978), 256–261 1985 NEHRP 85, 256–258 1988 UBC, 258–159 1997 UBC, 259–261 Approximate analysis, 13 of earthquake ground motion response, 205 for short-duration impulse loads, 112–117 Arbitrary dynamic loading, 121–134 Duhamel integral, 121–122 Newmark’s numerical method, 127–134 numerical formulation of equation of motion, 123 numerical integration methods, 124–127 step-by-step integration method, 123–124 Basic Structural Dynamics James C. Anderson and Farzad Naeim Copyright © 2012 John Wiley & Sons, Inc. 265 266 INDEX ASCE (American Society of Civil Engineers), 251 ASCE, 7, 232–233, 261 Assumed deflection pattern method, 14 ATC (Applied Technology Council), 256 ATC 3–06, see Applied Technology Council 3–06 resource document for model codes (1978) Attenuation relations, 211–212 Axial load effects, 10 multiple-degree-of-freedom systems, 162–164 single-degree-of-freedom systems, 42–44 Beating, 82 Bernoulli, Johann, 8 Betti’s theorem (law), 153–154 Blast-induced loads, 2 Block pulse, 101 Bozorgnia, Y., 212 Building code seismic provisions, 232–244 defining design criteria for buildings, 217 equivalent lateral force procedure, 234–237, 241–242 historical development of, 249–261 1978 ATC 3–06 resource document for model codes, 256–261 2000–2009 International Building Code, 261 overview, 250–256 modal response spectrum procedure, 234, 237–244 new generation of attenuation relations in, 211–212 regional and local codes, 232 California: California Building Code, 232, 261 California Strong Motion Instrumentation Program, 246, 247 earthquakes in, 207, 209, 218–219, 224, 240, 250 Field Act, 250–251 model codes for California building codes, 251–252 Riley Act, 250 California Building Code (CBC), 232, 261 California Strong Motion Instrumentation Program (CSMIP), 246, 247 Campbell, K. W., 212 CBC (California Building Code), 232, 261 Changing coordinates, MDOF systems, 156–159 Circum-Pacific belt, 203 Close-coupled systems, 159 Clough, R., 166 Conservation laws, 8 Conservative forces, 8 Constant acceleration method, 124, 129 Constantinides, Margarita, 190 Constraints, 8 Continuous parameters, SDOF systems, 31–37 Critical damping, 61–62, 66 Crust (of Earth), 203 CSMIP (California Strong Motion Instrumentation Program), 246, 247 D’Alembert, Jean le Rond, 8–9 D’Alembert’s principle, 8–9, 19–20 Damped dynamic systems, harmonic loading response for, 84–90 Damped force vibration, 174–178 Damped free vibration, SDOF systems, 61–72 logarithmic decrement, 66–67 radical positive, 67–72 rotating vector form, 63–65 Damped rectangular pulse, 108 Damping: critical, 61–62, 66 in discrete-parameter systems, 23 generalized, 24 and harmonic loading response, 91–95 overdamped systems, 67 viscous, 139–140 Damping coefficient, 10 Damping forces, 9, 23, 31, 139, 184 INDEX Damping ratios, 177 and harmonic loading, 86, 92, 93 single-degree-of-freedom systems, 67–72 Dead load, 10 Deflected shape, 144–145 and earthquake motion, 216 frequency equation for, 143 fundamental period in transverse direction, 55–58 selection of, 25, 60 static, 14, 22, 33, 56, 57 true, 58 Deflection: assumed deflection pattern method, 14 reciprocal, Maxwell’s law of, 154 Deflection amplification factor (seismic design), 234 Degrees of freedom, 8 and complexity of structural system, 10–11 defined, 8 reduction of, 13–14 Design spectra (earthquakes): ASCE 7 definition of spectral accelerations, 232–233 attenuation relations, 211–212 elastic design response spectrum, 208–215 Internet-based software for, 212 linear elastic response, 203–208 USGS Hazard Calculator, 213–215 Deterministic analysis, 1–2 Deterministic loads, periodic and nonperiodic, 2 Discrete parameters, SDOF systems, 23–31 Discretized model, 13 Displacement(s), 13, 20–22 generalized coordinates in SDOF systems, 22–46 axial load effect, 42–44 continuous parameters, 31–37 discrete parameters, 23–31 linear approximation, 44–46 transformation factors, 38–41 267 relative, 15, 22, 23, 173, 205, 215, 216 spectral analysis, 225 virtual: defined, 8 in single-degree-of-freedom systems, 20–22 Displacement function, 22 Displacement method, static equilibrium equation in, 9 DLF (dynamic load factor), 79 Duhamel integral: arbitrary dynamic loading, 121–122 seismic response, 203–206, 215–216 Dynamic (term), 1 Dynamic environment, 1–2 Dynamic equilibrium, 9–11. See also Equation of motion basic equation of, 9 under severe dynamic loading, 10 Dynamic force, effective, 16 Dynamic load factor (DLF), 79 Dynamic loads: evaluating response to: deterministic analysis, 1–2 nondeterministic analysis, 2 sources of, 2 types of, 2–3 Dynamic nonlinear analysis, MDOF systems, 185–189 Earthquakes: ground motion in SDOF systems, 18–19 and plate tectonics, 202–203 seismic accelerometers and seismographs, 95–97 Earthquake engineering, 201. See also Seismic response Earthquake loads: design spectra. See also Building code seismic provisions attenuation relations, 211–212 elastic design response spectrum, 208–215 Internet-based software for, 212 linear elastic response, 203–208 268 INDEX Earthquake loads: (continued ) USGS Hazard Calculator, 213–215 duration of, 2 Effective dynamic force, 16 Eigenvalue equation, 141 Elastic design response spectrum, 208–215 Elastic properties, MDOF systems, 137–140 flexibility, 137–138 inertia, 139 stiffness, 138–139 viscous damping, 139–140 El Centro, California earthquake, 207, 209, 218–219, 240 Environmental loads, sources of, 2 Equation of motion, 9 arbitrary dynamic loading: numerical formulation of, 123–124 numerical integration methods, 126 damped free vibration, 61 harmonic response: damped dynamic systems, 84 undamped dynamic systems, 77 impulse loads, 101 damped rectangular pulse, 108 rectangular pulse, 104 seismic accelerometers and seismographs, 95–96 seismic response, 179 damped oscillator subjected to base acceleration, 203 linear elastic response, 206 SDOF systems, 215 undamped MDOF system with time-dependent force, 185 undamped oscillator, 205 for single-degree-of-freedom systems, 19–22 d’Alembert’s principle, 19–20 earthquake response, 215 and gravitational forces, 17 and linear approximation, 44 in terms of generalized coordinates and parameters, 24 virtual work (virtual displacements), 20–22 undamped free vibration, 141, 155 Equilibrium equations: time-dependent force, 15 undamped free vibration, 141 Equipment motions, loads from, 2 Equivalent lateral force procedure (seismic response), 234–237, 241–242 Equivalent static pressures, 3 FEDEASLab toolbox (MATLAB), 190–200 Field Act (California), 250–251 Filippou, Filip C., 190 First (fundamental) mode, 142 Flexibility, in MDOF systems, 137–138 Flexure, 31, 36, 100 Force: in continuous-parameter systems, 31 generalized, 24 Framing factor, 252 Free vibration, 51–72 damped, 61–72 logarithmic decrement, 66–67 radical positive, 67–72 rotating vector form, 63–65 defined, 51 multiple-degree-of-freedom systems, 141–153 single-degree-of-freedom systems, 61–72 undamped, 51–60, 141–149, 155 Rayleigh’s method, 58–60 rotating vector form, 53–58 selection of deflected shape, 60 single-degree-of-freedom systems, 51–60 Free-vibration decay, 91 Frequency equation, 142 Fundamental (first) mode, 142 Gauss Reduction method, MDOF systems, 189–190 INDEX Generalized coordinate(s): defined, 22 for multiple-degree-of-freedom systems, 156 for single-degree-of-freedom systems, 22–46 axial load effect, 42–44 continuous parameters, 31–37 discrete parameters, 23–31 linear approximation, 44–46 transformation factors, 38–41 Generalized parameters, 24 Geometric nonlinearity, 10 Gravitational forces, SDOF systems, 17 Gravity loads, 10 Half-power amplitude, 92 Half-power method, 92–93 Harmonic loading, 77–97 damped dynamic systems, 84–90 evaluation of damping, 91–95 seismic accelerometers and seismographs, 95–97 tripartite logarithmic plot, 91, 92 undamped dynamic systems, 77–84 Harmonic motion: at constant circular frequency, 63 simple, 52–53 Holzer method for shear buildings, 159–162 Housner, G. W., 209 Housner’s earthquake design spectrum, 208–209 IBC, see International Building Code ICBO (International Conference of Building Officials), 250 Imperial Valley, California earthquake, 207, 218–219, 224 Importance factors (seismic design), 233 Impulse loads, 101–117 damped rectangular pulse, 108 rectangular pulse, 104–107 short-duration, approximate analysis for, 112–117 triangular pulse, 109–112 Inertia, 139 269 Inertia forces, 10, 25, 31 causes, 23 components of, 139 d’Alembert’s principle, 9 damped forced vibration, 174 spectral analysis, 225 in systems with distributed mass, 216, 217 time-dependent, 15, 19 undamped free vibration, 155 International Building Code (IBC): 2000–2009 seismic provisions, 261 2009 IBC, 232 ASCE 7 provisions adopted by, 232–233, 261 NEHRP provisions adopted by, 261 and USGS Hazard Calculator, 213–215 International Conference of Building Officials (ICBO), 250 Inverse transformation, MDOF systems, 156–159 Japan, seismic design law in, 250, 253 Kanto, Japan earthquake, 250 Kinetic energy (KE), 6, 58, 59 Linear acceleration method, 124 Linear approximation: multiple-degree-of-freedom systems, 162–164 single-degree-of-freedom systems, 44–46 Linear elastic response spectra (seismic response), 203–208 Linear momentum, Newton’s second law of, 3 Linear variation, 126–127 Live load, 10 Load-mass factor, 39–41 Logarithmic decrement: damped free vibration, 66–67 defined, 66 Long Beach, California earthquake, 250 Long-duration nonperiodic loading, 2 Long-duration nonperiodic loads, 2 270 INDEX Los Angeles Building Code, 232, 251, 261 Lumped parameter method, 14 Mass, 3–10, 123 and arbitrary dynamic loading, 123, 125 and building codes, 250 in continuous-parameter systems, 31 and d’Alembert’s principle, 19 and damped force vibration, 174–176 in discrete-parameter systems, 23 distributed, 216 and earthquake ground motion, 18, 19 and elastic properties, 139, 140 generalized, 24, 28, 32, 36, 111, 165, 166 and gravitational forces, 17 lumped, 14, 19, 23, 139–140, 159, 217 and orthogonal mode shapes, 156, 157 properties of common shapes, 7 and seismic response, 179, 216–217, 221 and time-dependent force, 15 and transformation factors, 38–41 in undamped dynamic systems, 51 in undamped time-dependent force analysis, 165–167 and undamped vibration, 51 weight vs., 6 Mass moment of inertia, 4–7 Mass participation factors (building codes), 237, 241, 243–244 Material nonlinearity, 10 MATLAB applications: arbitrary dynamic loading, 129–134 FEDEASLab toolbox, 190–200 harmonic loading: damped dynamic system, 89–90 evaluation of damping, 93–95 in undamped dynamic systems, 80–81, 83–84 impulse loads: rectangular pulse, 106–107 short-duration, 114–117 multiple-degree-of-freedom systems, 190–200 free vibration, 151–153 inverse transformation, 158–159 seismic response, 226–232, 237–240, 243–244 undamped free vibration, 145–149 undamped time-dependent force analysis, 169–170, 173–174 Plot Tool, 70–72 seismic response, 226–232, 237–240, 243–244 single-degree-of-freedom systems: axial load effect, 43–44 with continuous parameters, 33–35, 37 damping ratios, 68–72 rotating vector form, 63–65 undamped free vibration, 54–55 Symbolic Math Toolbox, 33–35, 37, 43–44, 151–153, 169–170 Maxwell’s law of reciprocal deflections, 154 MDOF systems, see Multiple-degree-of-freedom systems Modal coordinates, see Normal coordinates Modal equations, MDOF systems: of damped force vibration, 174–178 for seismic response analysis, 179–180 for undamped time-dependent force analysis, 165–174 Modal response spectrum procedure (seismic response), 234, 237–244 Modal superposition method, 166 Model codes: 1978 ATC 3–06 resource document for model codes, 256–261 for California building codes, 251–252 International Building Code, 232, 261 Moment of inertia: defined, 4 mass, 4–7 Moment of momentum, 4 Momentum: angular, 3, 4 defined, 3 INDEX linear, 3 Newton’s second law of, 3 Motion. See also Equation of motion earthquake ground motion, see Earthquakes equipment, 2 Newton’s laws of, 3–8 properties of, 8 rotational, 4. See also Angular momentum Multiple-degree-of-freedom (MDOF) systems, 137–180 axial load effects (linear approximation), 162–164 Betti’s theorem (law), 153–154 changing coordinates (inverse transformation), 156–159 elastic properties, 137–140 flexibility, 137–138 inertia, 139 stiffness, 138–139 viscous damping, 139–140 free vibration, 149–153 Holzer method for shear buildings, 159–162 modal equations: of damped force vibration, 174–178 for seismic response analysis, 179–180 for undamped time-dependent force analysis, 165–174 nonlinear response of, 183–200 dynamic nonlinear analysis, 185–189 Gauss Reduction method, 189–190 MATLAB applications, 190–200 static nonlinear analysis, 184–188 orthogonality properties of mode shapes, 155–156 seismic response, 219–232 modal combinations for spectral analyses, 222–232 271 time history modal analysis, 221–222 undamped free vibration, 141–149 Multiple degrees of freedom, 10–11 National Earthquake Hazard Reduction Program (NEHRP), 256 IBC provisions from, 261 NEHRP 85, 256–258 Natural frequency: effect of damping on, 62–63, 68 and harmonic loading, 93 Holzer method, 160 seismic measurement, 96 in undamped dynamic systems, 77–79, 81, 83 NEHRP, see National Earthquake Hazard Reduction Program NEHRP 85(1985), 256–258 New generation of attenuation (NGA) relations, 211–212 Newmark, N. M., 127 Newmark-Hall earthquake design spectrum, 209–210 Newmark’s numerical method, arbitrary dynamic loading, 127–134 Newton, Sir Isaac, 3 Newton’s laws of motion, 3–8 first law, 3 second law, 3, 4, 7 third law, 3 Newton’s method, 160 NGA (new generation of attenuation) relations, 211–212 Nonconservative forces, 8 Nondeterministic analysis, 2 Nonlinearity: geometric, 10 material, 10 most common source of, 183 Nonlinear response, MDOF systems, 183–200 dynamic nonlinear analysis, 185–189 Gauss Reduction method, 189–190 MATLAB applications, 190–200 static nonlinear analysis, 184–188 Nonperiodic loads, 2 272 INDEX Normal (modal) coordinates: defined, 156 inverse transformation, 156–159 seismic response analysis, 219–220 Normal mode of vibration, 155–156 Northridge earthquake, 245–246, 248 Numerical integration methods: arbitrary dynamic loading, 124–134 earthquake response of SDOF systems, 215 Newmark’s numerical method, 127–134 Occupancy categories, 233 Occupancy load, 10 Olympia, Washington earthquake, 209 Orthogonality properties of mode shapes, MDOF systems, 155–156 Overdamped systems, 67 Parameters: generalized, 24 single-degree-of-freedom systems: continuous, 31–37 discrete, 23–31 P- effect, 10 PE (potential energy), 6, 58–59 Penzien, J., 166 Periodic loads, 2 Period of vibration, 253 fundamental, calculating, 235 and Rayleigh’s method, 59 using transformation factors, 39 Phase angle (term), 54 Plates, 202, 203 Plate tectonics, 202–203 Potential energy (PE), 6, 58–59 Principia (Sir Isaac Newton), 3 Principle of virtual work, 8 Properties of motion, 8 Pushover analysis: defined, 185 for multiple-degree-of-freedom systems, 184–188 Radical positive (damped free vibration), 67–72 Random dynamic loading, 2 Rayleigh, Lord, 14, 175 Rayleigh damping, MDOF systems, 175–176 Rayleigh’s method: damped forced vibration, 175–176, 185–187 multiple-degree-of-freedom systems, 175–176, 185–187 single-degree-of-freedom systems: for discrete parameters, 22–31 undamped free vibration, 58–60 Reciprocal deflections, Maxwell’s law of, 154 Rectangular pulse: damped, 108 ideal, 104–107 Relative displacement, 15, 22, 23, 173, 205, 215, 216 Relative velocity, 15, 22, 205 Resonance, 79–80, 86–88 and damping, 92 defined, 79 Resonate amplification, 92 Response modification factor (seismic design), 234 Response ratio, 79–80 Restoring force, 22, 23, 32, 123 damped force vibration, 174 static nonlinear analysis, 184 time-dependent force, 15 Riley Act (California), 250 Rotating vector form, SDOF systems: damped free vibration, 63–65 undamped free vibration, 53–58 Rotational inertia, 5 Rotational motion, 4 San Francisco building code, 252 San Francisco earthquake, 250 SDOF systems, see Single-degree-of-freedom systems SEAOC (Structural Engineers Association of California), 252, 253 INDEX SEAONC (Structural Engineers Association of Northern California), 251 Seismic accelerometers, 95, 96 Seismic design categories, 233, 234 Seismic response, 201–244 and building codes, 232–244 equivalent lateral force procedure, 234–237, 241–242 modal response spectrum procedure, 234, 237–244 elastic design response spectrum, 208–215 linear elastic response spectra, 203–208 multiple-degree-of-freedom systems, 219–232 modal combinations for spectral analyses, 222–232 modal equations for, 179–180 time history modal analysis, 221–222 single-degree-of-freedom systems, 215–219 Seismic zones, 253, 254 Seismographs, 95–97 Self-weight, 10 Severe dynamic loading, nonlinear behavior under, 10 Shanghai World Financial Center, 185, 187, 188 Shape function, 14, 22, 24–25, 30, 58 Shear, 31 base, 185, 217–218, 234–242, 244, 251–254, 256, 258–260 impulse loads, 103 lateral, 251 seismic design, 217–218, 221, 225, 226, 234–242, 244 spectral analysis, 225 static nonlinear analysis, 185, 186 story, 236, 242, 244, 246 Shear buildings: Holzer method for, 159–162 Newton’s method, 160 undamped free vibration, 143 Shear building approximation, 140, 142 Shock spectra, 110–112 273 Short-duration loads: impulse, approximate analysis for, 112–117 nonperiodic, 2 Simple harmonic loading, 2 Simple harmonic motion, 52–53 Single degree of freedom, 10 Single-degree-of-freedom (SDOF) systems, 13–46 damped free vibration, 61–72 and earthquake ground motion, 18–19 formulation of equation of motion, 19–22 d’Alembert’s principle, 19–20 virtual work (virtual displacements), 20–22 free-vibration response of, 51–72 damped free vibration, 61–72 undamped free vibration, 51–60 generalized coordinates for, 22–46 axial load effect, 42–44 continuous parameters, 31–37 discrete parameters, 23–31 linear approximation, 44–46 transformation factors, 38–41 gravitational forces in, 17 reduction of degrees of freedom, 13–14 seismic response, 215–219 with time-dependent force, 15–17 undamped free vibration, 51–60 Spatial shape function, 22 Spectral analyses, seismic response, 222–232 Static deflected shape method, 14 Static equilibrium: in displacement method, 9 equation of, 9 Static nonlinear (pushover) analysis, MDOF systems, 184–188 Steady state, 82 Step-by-step integration method, 123–124 Stiffness: axial load effects, 162–164 in continuous-parameter systems, 31 as function of time, 123 Gauss reduction, 190 generalized, 22, 24, 33, 36 274 INDEX Stiffness: (continued ) geometric, 44–45, 183, 185, 194, 196, 198 global, 190 Holzer method for shear buildings, 159 lateral, 29, 45, 162, 183 lateral force-resisting elements, 26 mode shapes, 156 multiple-degree-of-freedom systems, 137–139 static nonlinear analysis, 184, 186 story, 56–58, 140 string, 44 with time-dependent force, 15 undamped free vibration, 142, 146 undamped time-dependent force analysis, 165–167 for very large structural systems, 190 Stiffness proportional damping, 175, 176 Story stiffness, 56–58, 140 String stiffness, 44 Structural elements, in discrete-parameter systems, 23 Structural Engineers Association of California (SEAOC), 252, 253 Structural Engineers Association of Northern California (SEAONC), 251 Superposition, modal, 166 Superposition principle, in elastic systems, 10 Symbolic Math Toolbox (MATLAB), 33–35, 37, 43–44, 151–153, 169–170 System overstrength factor (seismic design), 234 Taft, California earthquake, 209 Time dependence: earthquake ground motion, 19 equation of dynamic equilibrium, 123 in static vs. dynamic problems, 9 Time-dependent force: generalized parameters: continuous parameters, 31 discrete parameters, 23, 24 multiple-degree-of-freedom systems: damped, 185 undamped, 165–174 single-degree-of-freedom systems, 15–17 Time history modal analysis (seismic response), 221–222 Torque, 4 Traite de Dynamique (Jean le Rond d’Alembert), 8–9 Transformation factors, SDOF systems, 38–41 Transient response, 82 Transitional mass, 7 Triangular pulse, 109–112 Tripartite logarithmic plot: harmonic loading response, 91, 92 Newmark-Hall earthquake design spectra, 210–211 seismic response, 206–208 True vibration shape, 25 UBC, see Uniform Building Code Undamped (term), 51 Undamped dynamic systems: Duhamel integral, 121–122 harmonic loading response, 77–84 time-dependent force analysis for undamped MDOF systems, 165–174 Undamped free vibration: multiple-degree-of-freedom systems, 141–149 single-degree-of-freedom systems, 51–60, 67 Rayleigh’s method, 58–60 rotating vector form, 53–58 selection of deflected shape, 60 Uniform Building Code (UBC): 1961 provisions, 253 1967 provisions, 254 1976 provisions, 254–256 1985 provisions, 256 1988 provisions, 258–259 1997 provisions, 259–261 enactment of seismic provisions, 250 INDEX US Geological Survey (USGS), 212 USGS Hazard Calculator, 213–215 Vehicle loads, 2 Velocity, relative, 15, 22, 205 Virtual displacement: defined, 8 single-degree-of-freedom systems, 20–23 Virtual work: principle of, 8 275 single-degree-of-freedom systems, 20–23 Viscous damping: harmonic loading, 84 multiple-degree-of-freedom systems, 139–140 Weight, mass vs., 6 Wind loads, 2–3 Work: concept of, 6–7 virtual, 8, 20–22