Case Studies of Damage to Tall Steel Moment-Frame Buildings in Southern California during Large San Andreas Earthquakes

Section: Discussionmentioning

confidence: 92%

Spatial Variability of "Did You Feel It?" Intensity Data: Insights into Sampling Biases in Historical Earthquake Intensity Distributions

Hough

2013

“…The normalized histograms of slip (m) in a finite-source inversion model of the magnitude 7.9 Denali earthquake of 2002 (Krishnan et al, 2006) and one stochastic source realization using the outlined method are shown in Figure 7. The similarity in the two distributions (with the exception of the frequency of subfaults with zero slip) suggests that a series of lognormal PDFs can indeed be used to define slip distribution in stochastic source models.…”

Section: Methodology Slip Distributionmentioning

confidence: 99%

“…generated by these models against the peak velocities generated by finite-source inversions of comparable earthquakes with similar magnitudes (also simulated using SPEC-FEM3D). The finite-source inversions selected for this exercise include that of the 2002 M w 7.9 Denali fault earthquake (Krishnan et al, 2006;Fig. 15) and the 2004 M w 6.0 Parkfield earthquake (Ji, 2004).…”

Section: Application To the Southern San Andreas Faultmentioning

confidence: 99%

“…Rupture-to-rafters simulations offer an alternative (and perhaps more realistic) approach for risk quantification and design of new structures (Krishnan et al, 2006(Krishnan et al, , 2011. Generating stochastic seismic source models for these simulations is a crucial step, given the limited number of credible source models from large historical earthquakes.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A Laboratory Earthquake‐Based Stochastic Seismic Source Generation Algorithm for Strike‐Slip Faults and its Application to the Southern San Andreas Fault

Siriki¹,

Bhat²,

Lü³

et al. 2015

There is a sparse number of credible source models available from largemagnitude past earthquakes. A stochastic source-model-generation algorithm thus becomes necessary for robust risk quantification using scenario earthquakes. We present an algorithm that combines the physics of fault ruptures as imaged in laboratory earthquakes with stress estimates on the fault constrained by field observations to generate stochastic source models for large-magnitude (M w 6.0-8.0) strike-slip earthquakes. The algorithm is validated through a statistical comparison of synthetic groundmotion histories from a stochastically generated source model for a magnitude 7.90 earthquake and a kinematic finite-source inversion of an equivalent magnitude past earthquake on a geometrically similar fault. The synthetic dataset comprises threecomponent ground-motion waveforms, computed at 636 sites in southern California, for 10 hypothetical rupture scenarios (five hypocenters, each with two rupture directions) on the southern San Andreas fault. A similar validation exercise is conducted for a magnitude 6.0 earthquake, the lower magnitude limit for the algorithm. Additionally, ground motions from the M w 7.9 earthquake simulations are compared against predictions by the Campbell-Bozorgnia Next Generation Attenuation relation, as well as the ShakeOut scenario earthquake. The algorithm is then applied to generate 50 source models for a hypothetical magnitude 7.9 earthquake originating at Parkfield, California, with rupture propagating from north to south (toward Wrightwood), similar to the 1857 Fort Tejon earthquake. Using the spectral element method, three-component ground-motion waveforms are computed in the Los Angeles basin for each scenario earthquake and the sensitivity of ground-shaking intensity to seismic source parameters (such as the percentage of asperity area relative to the fault area, rupture speed, and rise time) is studied.Online Material: Figures of source and simulated peak ground motions for an M w 6.05 scenario on the southern San Andreas fault, and table of V S30 and basin depth at stations.

“…From a nonlinear time history analysis, the authors found that some 20-story models exceeded their interstory drift capacities, including models with higher strengths. Krishnan et al (2006) studied the response of a common type of building in the Los Angeles area to simulated ground motions from hypothetical magnitude 7.9 ruptures on the southern San Andreas fault. They used a fully three-dimensional building model to compare the responses of 18-story steel MRF buildings designed to the 1982 and 1997 Uniform Building Codes (UBCs).…”

Section: Introductionmentioning

confidence: 99%

Long-Period Building Response to Earthquakes in the San Francisco Bay Area

Olsen¹,

Aagaard²,

Heaton³

2008

This article reports a study of modeled, long-period building responses to ground-motion simulations of earthquakes in the San Francisco Bay Area. The earthquakes include the 1989 magnitude 6.9 Loma Prieta earthquake, a magnitude 7.8 simulation of the 1906 San Francisco earthquake, and two hypothetical magnitude 7.8 northern San Andreas fault earthquakes with hypocenters north and south of San Francisco. We use the simulated ground motions to excite nonlinear models of 20-story, steel, welded moment-resisting frame (MRF) buildings. We consider MRF buildings designed with two different strengths and modeled with either ductile or brittle welds. Using peak interstory drift ratio (IDR) as a performance measure, the stiffer, higher strength building models outperform the equivalent more flexible, lower strength designs. The hypothetical magnitude 7.8 earthquake with hypocenter north of San Francisco produces the most severe ground motions. In this simulation, the responses of the more flexible, lower strength building model with brittle welds exceed an IDR of 2.5% (that is, threaten life safety) on 54% of the urban area, compared to 4.6% of the urban area for the stiffer, higher strength building with ductile welds. We also use the simulated ground motions to predict the maximum isolator displacement of base-isolated buildings with linear, single-degree-of-freedom (SDOF) models. For two existing 3-sec isolator systems near San Francisco, the design maximum displacement is 0.5 m, and our simulations predict isolator displacements for this type of system in excess of 0.5 m in many urban areas. This article demonstrates that a large, 1906-like earthquake could cause significant damage to long-period buildings in the San Francisco Bay Area.