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 Vs 30 § Combine using matched filters (1 Hz) and summing in time domain 03/24/2004 NGA Workshop: Validation 1
Deterministic Methodology (f < 1 Hz) 03/24/2004 NGA Workshop: Validation 2
Stochastic Methodology (f > 1 Hz) 03/24/2004 NGA Workshop: Validation 3
Site Amplification Factors (Borcherdt, 1994) Applied in Fourier domain, although strictly defined for response spectra. Fv Fa 03/24/2004 NGA Workshop: Validation 4
Source Rupture Model - slip distribution - rupture time - slip velocity function Tp Tr A h 03/24/2004 NGA Workshop: Validation 5
1994 Northridge Mw 6. 7 - strong motion recordings at 69 sites - complex basin geology (SCEC v 2. 2 b) - slip distribution after Hartzell et al. (1996) 03/24/2004 NGA Workshop: Validation 6
Time History Comparison Site type C Site type B 03/24/2004 Site type D NGA Workshop: Validation 7
Observed and Simulated PGA and PGV 03/24/2004 NGA Workshop: Validation 8
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 03/24/2004 NGA Workshop: Validation 9
Residuals show no significant azimuthal trends (slight over-prediction in SF valley) 03/24/2004 NGA Workshop: Validation 10
1989 Loma Prieta Mw 6. 9 - strong motion recordings at 32 sites - lateral velocity change across SAF - slip distribution after Wald et al. (1991) 03/24/2004 NGA Workshop: Validation 11
Time History Comparison Site type BC Site type C 03/24/2004 Site type D NGA Workshop: Validation 12
Observed and Simulated PGA and PGV 03/24/2004 NGA Workshop: Validation 13
Model Bias and Standard Error: Response Spectra Global goodness-of-fit (32 sites, avg. horizontal) Residuals vs. distance / site type Average horizontal 03/24/2004 NGA Workshop: Validation 14
Residuals show no significant azimuthal trends (over-prediction in Gilroy at longer periods) 03/24/2004 NGA Workshop: Validation 15
CONCLUSIONS 03/24/2004 NGA Workshop: Validation 16
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