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BROADBAND SIMULATION METHODOLOGY: A HYBRID DETERMINISTIC AND STOCHASTIC APPROACH. Robert Graves, Arben Pitarka, Nancy Collins, and Paul Somerville URS Corporation. Use Deterministic Methodology at Low Frequencies (f < 1 Hz) Use Stochastic Methodology at High Frequencies (f > 1 Hz)
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BROADBAND SIMULATION METHODOLOGY: A HYBRID DETERMINISTIC AND STOCHASTIC APPROACH Robert Graves, Arben Pitarka, Nancy Collins, and Paul Somerville URS Corporation • Use Deterministic Methodology at Low Frequencies (f < 1 Hz) • Use Stochastic Methodology at High Frequencies (f > 1 Hz) • Apply Site-specific Amplification Factors Based on Vs30 • Combine using matched filters (1 Hz) and summing in time domain NGA Workshop: Validation
Deterministic Methodology (f < 1 Hz) NGA Workshop: Validation
Stochastic Methodology (f > 1 Hz) NGA Workshop: Validation
Site Amplification Factors (Borcherdt, 1994) Applied in Fourier domain, although strictly defined for response spectra. Fv Fa NGA Workshop: Validation
Source Rupture Model - slip distribution - rupture time - slip velocity function Tp Tr A h NGA Workshop: Validation
1994 Northridge Mw 6.7 - strong motion recordings at 69 sites - complex basin geology (SCEC v2.2b) - slip distribution after Hartzell et al. (1996) NGA Workshop: Validation
Time History Comparison Site type C Site type B Site type D NGA Workshop: Validation
Observed and Simulated PGA and PGV NGA Workshop: Validation
Model Bias and Standard Error: Response Spectra Global goodness-of-fit (38 sites, avg. horizontal) Residuals vs. distance / site type Average horizontal without site factors without site factors NGA Workshop: Validation
Residuals show no significant azimuthal trends (slight over-prediction in SF valley) NGA Workshop: Validation
1989 Loma Prieta Mw 6.9 - strong motion recordings at 32 sites - lateral velocity change across SAF - slip distribution after Wald et al. (1991) NGA Workshop: Validation
Time History Comparison Site type BC Site type C Site type D NGA Workshop: Validation
Observed and Simulated PGA and PGV NGA Workshop: Validation
Model Bias and Standard Error: Response Spectra Global goodness-of-fit (32 sites, avg. horizontal) Residuals vs. distance / site type Average horizontal NGA Workshop: Validation
Residuals show no significant azimuthal trends (over-prediction in Gilroy at longer periods) NGA Workshop: Validation
CONCLUSIONS NGA Workshop: Validation