engineering perspective on application of simulated ground motions jonathan p. stewart & emel...
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Engineering Perspective on Application of Simulated Ground Motions
Jonathan P. Stewart & Emel SeyhanUniversity of California, Los Angeles
Robert W. GravesUSGS Pasadena
Outline
• Need for verification, validation, and calibration (VVC)
• Validation procedures• Validation of ShakeOut motions• Calibration of high frequency IMs from Graves-
Pitarka hybrid procedure
Need for VVC
• Verification: consistency of motions across computational platforms for common conditions
Bielak et al., 2010
ShakeOut: example vel.(t)
Need for VVC
• Verification• Validation: results of analysis generally consistent
with recordings
Need for VVC
• Verification• Validation• Calibration: adjustment of parameters to achieve
desired attribute of simulated motions
Validation Procedures
• Waveform comparison using earthquake data
Graves and Pitarka, 2010
Validation Procedures
• Waveform comparison using earthquake data
• IM comparison to earthquake data
Closest Distance (km)
Graves and Pitarka, 2010
Validation Procedures
• Waveform comparison using earthquake data
• IM comparison to earthquake data
• IM comparison to GMPEs
Frankel, 2009
ShakeOut Validation
• Motions from hybrid procedure
ShakeOut Validation
• Motions from hybrid procedure
• Analysis of residuals– 4 NGA GMPEs– R, Vs30, Z for site i
ShakeOut Validation
• Motions from hybrid procedure
• Analysis of residuals• Too-fast distance
attenuation
SO
PH
R
R
Star et al., 20xx
ShakeOut Validation
• Motions from hybrid procedure
• Analysis of residuals• Too-fast distance
attenuation• Too-low intra-event
standard deviation
Star et al., 20xx
Calibration
• Adjustment to high frequency component of hybrid procedure
Calibration
• Adjustment to high frequency component of hybrid procedure
• Increase Q to slow distance attenuation
Seyhan et al., 20xx
Calibration
• Adjustment to high frequency component of hybrid procedure
• Increase Q to slow distance attenuation
Seyhan et al., 20xx
Calibration
• Adjustment to high frequency component of hybrid procedure
• Increase Q to slow distance attenuation
• Randomize Fourier amplitude spectra
Seyhan et al., 20xx
Ar fAfA exp
sA = f(M)
Calibration
• Adjustment to high frequency component of hybrid procedure
• Increase Q to slow distance attenuation
• Randomize Fourier amplitude spectra
Seyhan et al., 20xx
Conclusions
• Engineers want to use simulated motions• Needed for conditions having sparse data• Verification – Validation – Calibration– Each step documented– Avoid circularity in use of data
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