Location
San Diego, California
Presentation Date
29 May 2010, 8:00 am - 9:30 am
Abstract
This paper is an attempt to clarify a possible confusion regarding which maximum ground acceleration (amax) should be used when performing a site-specific liquefaction analysis. Usually, one-dimensional free-field site response analysis is performed to estimate amax at the foundation elevation and the strain-compatible soil parameters within the soil profile. From the soil-structure interaction (SSI) analysis perspective, this calculation is repeated for the best-estimate, lower-bound, and upper-bound soil profiles. For this, the shear moduli are adjusted using a coefficient of variation (cv) to account for the spatial variation in the soil properties and the uncertainties in SSI calculations. The procedure is explained in ASCE 4-98. On the other hand, establishing a design amax is open to interpretation in current guidelines and procedures that discuss the liquefaction analysis. The simplified cyclic stress ratio (CSR) procedure is an empirical method that uses a depth dependent stress reduction factor (rd). In the CSR procedure, amax corresponds to the magnitude of an earthquake that is assumed to occur at the site. The question is, should the amax from the one-dimensional response analysis using the best estimate (or representative) soil profile be used in liquefaction analysis? Or, should the average or possibly the least favorable amax be used? If the least favorable amax is used, then the corresponding soil profile should also be used in liquefaction analyses. Historically, rd values are based on studies done using different earthquake time histories and average soil profiles. In this study, a small scale parametric study is conducted to show that the average amax from the one-dimensional response analyses with best estimate soil profile is appropriate to use in simplified liquefaction analyses.
Department(s)
Civil, Architectural and Environmental Engineering
Meeting Name
5th International Conference on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics
Publisher
Missouri University of Science and Technology
Document Version
Final Version
Rights
© 2010 Missouri University of Science and Technology, All rights reserved.
Creative Commons Licensing
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.
Document Type
Article - Conference proceedings
File Type
text
Language
English
Recommended Citation
Sarica, Rabia Z., "Selection of an Appropriate amax for Liquefaction Analyses from One-Dimensional Site Response Analyses" (2010). International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics. 14.
https://scholarsmine.mst.edu/icrageesd/05icrageesd/session03/14
Included in
Selection of an Appropriate amax for Liquefaction Analyses from One-Dimensional Site Response Analyses
San Diego, California
This paper is an attempt to clarify a possible confusion regarding which maximum ground acceleration (amax) should be used when performing a site-specific liquefaction analysis. Usually, one-dimensional free-field site response analysis is performed to estimate amax at the foundation elevation and the strain-compatible soil parameters within the soil profile. From the soil-structure interaction (SSI) analysis perspective, this calculation is repeated for the best-estimate, lower-bound, and upper-bound soil profiles. For this, the shear moduli are adjusted using a coefficient of variation (cv) to account for the spatial variation in the soil properties and the uncertainties in SSI calculations. The procedure is explained in ASCE 4-98. On the other hand, establishing a design amax is open to interpretation in current guidelines and procedures that discuss the liquefaction analysis. The simplified cyclic stress ratio (CSR) procedure is an empirical method that uses a depth dependent stress reduction factor (rd). In the CSR procedure, amax corresponds to the magnitude of an earthquake that is assumed to occur at the site. The question is, should the amax from the one-dimensional response analysis using the best estimate (or representative) soil profile be used in liquefaction analysis? Or, should the average or possibly the least favorable amax be used? If the least favorable amax is used, then the corresponding soil profile should also be used in liquefaction analyses. Historically, rd values are based on studies done using different earthquake time histories and average soil profiles. In this study, a small scale parametric study is conducted to show that the average amax from the one-dimensional response analyses with best estimate soil profile is appropriate to use in simplified liquefaction analyses.
