from actual earthquakes are applied in incremental dynamic analyses of the building models. In the incremental dynamic analyses, the fault-normal and vertical components (if available) are scaled by scaling factors ranging from 0.6 to 2.0 with increments of 0.2. The scaled ground motion records are then applied to the building models.
ifornia region that is compatible with the SCEC Community Velocity model is created using an advanced unstructured mesher, CUBIT, developed by Sandia National Laboratory [64] and adapted as GeoCubit for large-scale geological applications [7]. The limitation on the frequency content of the simulated ground motions is primarily due to insufficient resolution of the model of the seismic wave speed structure of the earth for propagating high-frequency waves, and the higher frequency waveforms need to be obtained differently. In this ground motion simulation, a variant of the classi- cal Empirical Green’s Function (EGF) method presented by Mourhatch and Krishnan [56] is applied at each of the 636 sites to produce high-frequency (0.5 - 5 Hz) ground motion waveforms. Then, using a matching pair of low-pass and high-pass Butterworth filters, the two sets of ground motion time histories are synthesized to give broadband (0 - 5 Hz) ground motion waveforms.
Amplification due to site-specific geology is not considered in the low-frequency portion of the simulations. However, Krishnan et al. [46, 47] suggest that site amplification is likely to be minimal for low-frequency (<0.5 Hz) waves, and consequently the effects on long-period (low- frequency) structures such as the ones considered in this study are also likely to be minimal. As for the high-frequency (0 - 5 Hz) portion of the simulations, the generated ground motion time histories are basically constructed from real ground motions that are recorded at the ground surface at sites reasonably close to the target site, and contain potential amplifications due to site-specific geology.
In Figure 4.1, a map of the greater Los Angeles metropolitan area is presented, showing the locations of the 636 sites where ground motion time histories are generated and the building models are analyzed. The relation of the study area to the 290 km hypothetical rupture of the San Andreas fault is shown in the inset. Maps of peak ground acceleration (PGA), peak ground velocities (PGV), and peak ground displacements (PGD) realized in the earthquake scenario are shown for EW and NS directions in Figure 4.2. Peak ground velocities are in the range of 1-2 m/s in the San Fernando Valley, 0.25-0.75 m/s in the Los Angeles basin, and 0.25-1 m/s in the San Gabriel Valley. Ground acceleration, velocity, and displacement time-histories for four sites located near downtown Los Angeles, Pasadena, Santa Monica, and Long Beach are shown in Figures 4.3 and 4.4.
−119˚ −118.75˚ −118.5˚ −118.25˚ −118˚ −117.75˚
33.75˚
34˚
34.25˚
Anaheim Azusa Baldwin Park Beverly Hills
Brea Burbank
Canoga Park
Compton El Segundo Encino
Hollywood
Huntington Beach Irvine La Canada
La Puente
Long Beach Los Angeles Malibu
Northridge
Norwalk Pasadena
Point Dume
San Fernando
Santa Ana Santa Monica
Simi Valley
Thousand Oaks
Torrance
Whittier
−121˚−120˚−119˚−118˚
34˚
35˚
36˚
Los Angeles
Figure 4.1:Geographic scope of the 1857-like scenario earthquake simulations. Black triangles represent the 636 sites where ground motion time histories are generated and the building models are an- alyzed. The color scheme reflects topography with green representing low elevation and yellow representing high elevations. The red line in the inset shows the surface trace of the hypothetical 290 km rupture of the San Andreas fault. The nucleation point of the rupture is indicated by a yellow star. In the inset, the extent of the greater Los Angeles metropolitan region, which is the geographic focus of this study, is indicated by a blue rectangle.
−119˚ −118.75˚ −118.5˚ −118.25˚ −118˚ −117.75˚
33.75˚
34˚
34.25˚
−119˚ −118.75˚ −118.5˚ −118.25˚ −118˚ −117.75˚
33.75˚
34˚
34.25˚
Anaheim Azusa Baldwin Park Beverly Hills
Brea Burbank
Canoga Park
Compton El Segundo Encino
Hollywood
Huntington Beach Irvine La Canada
La Puente
Long Beach Los Angeles Malibu
Northridge
Norwalk Pasadena
Point Dume
San Fernando
Santa Ana Santa Monica
Simi Valley
Thousand Oaks
Torrance
Whittier
0.00 0.25 0.50 0.75 1.00 East−West PGA (g)
−119˚ −118.75˚ −118.5˚ −118.25˚ −118˚ −117.75˚
33.75˚
34˚
34.25˚
−119˚ −118.75˚ −118.5˚ −118.25˚ −118˚ −117.75˚
33.75˚
34˚
34.25˚
Anaheim Azusa Baldwin Park Beverly Hills
Brea Burbank
Canoga Park
Compton El Segundo Encino
Hollywood
Huntington Beach Irvine La Canada
La Puente
Long Beach Los Angeles Malibu
Northridge
Norwalk Pasadena
Point Dume
San Fernando
Santa Ana Santa Monica
Simi Valley
Thousand Oaks
Torrance
Whittier
0.00 0.25 0.50 0.75 1.00 North−South PGA (g)
−119˚ −118.75˚ −118.5˚ −118.25˚ −118˚ −117.75˚
33.75˚
34˚
34.25˚
−119˚ −118.75˚ −118.5˚ −118.25˚ −118˚ −117.75˚
33.75˚
34˚
34.25˚
Anaheim Azusa Baldwin Park Beverly Hills
Brea Burbank
Canoga Park
Compton El Segundo Encino
Hollywood
Huntington Beach Irvine La Canada
La Puente
Long Beach Los Angeles Malibu
Northridge
Norwalk Pasadena
Point Dume
San Fernando
Santa Ana Santa Monica
Simi Valley
Thousand Oaks
Torrance
Whittier
0.0 0.5 1.0 1.5 2.0
East−West PGV (m/s)
−119˚ −118.75˚ −118.5˚ −118.25˚ −118˚ −117.75˚
33.75˚
34˚
34.25˚
−119˚ −118.75˚ −118.5˚ −118.25˚ −118˚ −117.75˚
33.75˚
34˚
34.25˚
Anaheim Azusa Baldwin Park Beverly Hills
Brea Burbank
Canoga Park
Compton El Segundo Encino
Hollywood
Huntington Beach Irvine La Canada
La Puente
Long Beach Los Angeles Malibu
Northridge
Norwalk Pasadena
Point Dume
San Fernando
Santa Ana Santa Monica
Simi Valley
Thousand Oaks
Torrance
Whittier
0.0 0.5 1.0 1.5 2.0
North−South PGV (m/s)
−119˚ −118.75˚ −118.5˚ −118.25˚ −118˚ −117.75˚
33.75˚
34˚
34.25˚
−119˚ −118.75˚ −118.5˚ −118.25˚ −118˚ −117.75˚
33.75˚
34˚
34.25˚
Anaheim Azusa Baldwin Park Beverly Hills
Brea Burbank
Canoga Park
Compton El Segundo Encino
Hollywood
Huntington Beach Irvine La Canada
La Puente
Long Beach Los Angeles Malibu
Northridge
Norwalk Pasadena
Point Dume
San Fernando
Santa Ana Santa Monica
Simi Valley
Thousand Oaks
Torrance
Whittier
0.0 0.5 1.0 1.5 2.0
East−West PGD (m)
−119˚ −118.75˚ −118.5˚ −118.25˚ −118˚ −117.75˚
33.75˚
34˚
34.25˚
−119˚ −118.75˚ −118.5˚ −118.25˚ −118˚ −117.75˚
33.75˚
34˚
34.25˚
Anaheim Azusa Baldwin Park Beverly Hills
Brea Burbank
Canoga Park
Compton El Segundo Encino
Hollywood
Huntington Beach Irvine La Canada
La Puente
Long Beach Los Angeles Malibu
Northridge
Norwalk Pasadena
Point Dume
San Fernando
Santa Ana Santa Monica
Simi Valley
Thousand Oaks
Torrance
Whittier
0.0 0.5 1.0 1.5 2.0
North−South PGD (m)
Figure 4.2:Peak ground accelerations (PGA), peak ground velocities (PGV), and peak ground displacements (PGD) realized in the greater Los Angeles metropolitan area for the east-west and north-south directions in the simulated 1857-like scenario earthquake.
−0.25 0.00 0.25
Los Angeles East−West Component
Acc. (g)
−1.00 0.00 1.00
Vel. (m/s)
0 25 50 75 100 125 150 175 200 225 250
−1.00 0.00 1.00
Dsp. (m)
Time (sec)
−0.25 0.00 0.25
Pasadena East−West Component
Acc. (g)
−1.00 0.00 1.00
Vel. (m/s)
0 25 50 75 100 125 150 175 200 225 250
−1.00 0.00 1.00
Dsp. (m)
Time (sec)
−0.25 0.00 0.25
North−South Component
Acc. (g)
−1.00 0.00 1.00
Vel. (m/s)
0 25 50 75 100 125 150 175 200 225 250
−1.00 0.00 1.00
Dsp. (m)
Time (sec)
−0.25 0.00 0.25
North−South Component
Acc. (g)
−1.00 0.00 1.00
Vel. (m/s)
0 25 50 75 100 125 150 175 200 225 250
−1.00 0.00 1.00
Dsp. (m)
Time (sec)
−0.25 0.00 0.25
Vertical Component
Acc. (g)
−1.00 0.00 1.00
Vel. (m/s)
0 25 50 75 100 125 150 175 200 225 250
−1.00 0.00 1.00
Dsp. (m)
Time (sec)
−0.25 0.00 0.25
Vertical Component
Acc. (g)
−1.00 0.00 1.00
Vel. (m/s)
0 25 50 75 100 125 150 175 200 225 250
−1.00 0.00 1.00
Dsp. (m)
Time (sec)
Figure 4.3:East-west, north-south, and vertical component ground acceleration, velocity, and displacement time histories realized in Los Angeles and Pasadena in the 1857-like earthquake scenario.
−0.25 0.00 0.25
Santa Monica East−West Component
Acc. (g)
−1.00 0.00 1.00
Vel. (m/s)
0 25 50 75 100 125 150 175 200 225 250
−1.00 0.00 1.00
Dsp. (m)
Time (sec)
−0.25 0.00 0.25
Long Beach East−West Component
Acc. (g)
−1.00 0.00 1.00
Vel. (m/s)
0 25 50 75 100 125 150 175 200 225 250
−1.00 0.00 1.00
Dsp. (m)
Time (sec)
−0.25 0.00 0.25
North−South Component
Acc. (g)
−1.00 0.00 1.00
Vel. (m/s)
0 25 50 75 100 125 150 175 200 225 250
−1.00 0.00 1.00
Dsp. (m)
Time (sec)
−0.25 0.00 0.25
North−South Component
Acc. (g)
−1.00 0.00 1.00
Vel. (m/s)
0 25 50 75 100 125 150 175 200 225 250
−1.00 0.00 1.00
Dsp. (m)
Time (sec)
−0.25 0.00 0.25
Vertical Component
Acc. (g)
−1.00 0.00 1.00
Vel. (m/s)
0 25 50 75 100 125 150 175 200 225 250
−1.00 0.00 1.00
Dsp. (m)
Time (sec)
−0.25 0.00 0.25
Vertical Component
Acc. (g)
−1.00 0.00 1.00
Vel. (m/s)
0 25 50 75 100 125 150 175 200 225 250
−1.00 0.00 1.00
Dsp. (m)
Time (sec)
Figure 4.4:East-west, north-south, and vertical component ground acceleration, velocity, and displacement time histories realized in Santa Monica and Long Beach in the 1857-like earthquake scenario.