Location

San Diego, California

Session Start Date

3-26-2001

Session End Date

3-31-2001

Abstract

It has been recognized that the nature of the surface deposits can significantly alter the incident ground motion characteristics. Particularly, in large earthquakes, the soil deposits behave as a non-linear material. The characteristics of soil response during earthquake excitations are analyzed at Chiba vertical array site in Japan. Both frequency domain and time domain analyses are performed for investigation of nonlinear soil response and identification of dynamic soil properties. In the frequency domain analysis, the frequency-dependent transfer function of soil is calculated as a ratio of the spectrum at uphole to the spectrum at downhole. Shear modulus and damping ratio are evaluated from peaks in the transfer function amplitude. In the time domain analysis, acceleration data from the site are processed directly for evaluation of site shear stress-strain hysteresis curve. The shear modulus and damping ratio are evaluated from shear stress-strain hysteresis curve using equivalent shear modulus and damping ratio approach. The results of both methods reveal the non-linear soil behavior for recorded strong ground motion at the site with surface PGA of more than 300 gal. The variation of identified soil shear modulus and damping ratio with shear strain amplitude is also examined at the site for both methods. These results indicated that both methods and laboratory results are in general agreement.

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

Identification of Dynamic Soil Properties Using Vertical Array Recordings

San Diego, California

It has been recognized that the nature of the surface deposits can significantly alter the incident ground motion characteristics. Particularly, in large earthquakes, the soil deposits behave as a non-linear material. The characteristics of soil response during earthquake excitations are analyzed at Chiba vertical array site in Japan. Both frequency domain and time domain analyses are performed for investigation of nonlinear soil response and identification of dynamic soil properties. In the frequency domain analysis, the frequency-dependent transfer function of soil is calculated as a ratio of the spectrum at uphole to the spectrum at downhole. Shear modulus and damping ratio are evaluated from peaks in the transfer function amplitude. In the time domain analysis, acceleration data from the site are processed directly for evaluation of site shear stress-strain hysteresis curve. The shear modulus and damping ratio are evaluated from shear stress-strain hysteresis curve using equivalent shear modulus and damping ratio approach. The results of both methods reveal the non-linear soil behavior for recorded strong ground motion at the site with surface PGA of more than 300 gal. The variation of identified soil shear modulus and damping ratio with shear strain amplitude is also examined at the site for both methods. These results indicated that both methods and laboratory results are in general agreement.