Location

San Diego, California

Session Start Date

3-26-2001

Session End Date

3-31-2001

Abstract

Microtremor measurements are conducted using arrays of sensors at six strong motion stations in Taiwan where the peak ground accelerations over 400 cm/s2 were recorded during the 1999 Chi-Chi earthquake. Shallow shear wave velocity profiles of these stations are estimated based on an inverse analysis of microtremor dispersion characteristics and H/V spectra. At Wufeng (TCU065) where building damage was the most extensive among others, a thick soft surface layer with a shear wave velocity less than or equal to about 200 m/s overlies a stiff layer with Vs greater than 400 m/s at a depth of about 30 m. At other stations, stiff layers with Vs greater than 300-400 m/s occur from the ground surface or at a depth less than 20 m. Linear and equivalent linear analyses are conducted using the estimated Vs profiles. The natural site periods computed from an equivalent linear analysis are generally consistent with the peak periods of the response acceleration spectra of the recorded strong motions, but they are considerably longer than those estimated from a linear analysis, regardless of the value of the shallow shear wave velocity. This suggests that local soil conditions including nonlinear soil behavior might have had significant effects on the ground surface motion and performance of buildings during the earthquake.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Meeting Name

Fourth Conference

Publisher

University of Missouri--Rolla

Publication Date

3-26-2001

Document Version

Final Version

Rights

© 2001 University of Missouri--Rolla, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Mar 26th, 12:00 AM Mar 31st, 12:00 AM

Site Effects Estimated From Microtremor Measurements at Selected Strong Motion Stations in Taiwan

San Diego, California

Microtremor measurements are conducted using arrays of sensors at six strong motion stations in Taiwan where the peak ground accelerations over 400 cm/s2 were recorded during the 1999 Chi-Chi earthquake. Shallow shear wave velocity profiles of these stations are estimated based on an inverse analysis of microtremor dispersion characteristics and H/V spectra. At Wufeng (TCU065) where building damage was the most extensive among others, a thick soft surface layer with a shear wave velocity less than or equal to about 200 m/s overlies a stiff layer with Vs greater than 400 m/s at a depth of about 30 m. At other stations, stiff layers with Vs greater than 300-400 m/s occur from the ground surface or at a depth less than 20 m. Linear and equivalent linear analyses are conducted using the estimated Vs profiles. The natural site periods computed from an equivalent linear analysis are generally consistent with the peak periods of the response acceleration spectra of the recorded strong motions, but they are considerably longer than those estimated from a linear analysis, regardless of the value of the shallow shear wave velocity. This suggests that local soil conditions including nonlinear soil behavior might have had significant effects on the ground surface motion and performance of buildings during the earthquake.