Location

San Diego, California

Session Start Date

5-24-2010

Session End Date

5-29-2010

Abstract

Earthquake waves propagate mainly in rock mass from hypocenter to the bedrock directly underneath a monitoring station. Then, it propagates as shear waves from the bedrock to a geophone, where the surface motion is measured. For a deposit with uniform soil layers of horizontal interfaces, one-dimensional finite element analysis can be performed to analyze the dynamic responses of a horizontal soil deposit. In an ideal dynamic soil-structure interaction analysis, seismic waves are propagated from the bedrock through soils and foundations, and then to structure. Thus, it is necessary to obtain the bedrock motion from a measured surface motion registered in geophone. Conventionally the process is called de-convolution. The de-convolution is treated as wave propagation in a frequency domain involving damping factor independent of motion velocity. The time-domain analysis is usually used in assessing the effects of soil-structure interaction. The time domain analysis requires the use of viscous damping proportional to motion velocity. Thus, it is necessary to device a method for the evaluation of viscous damping that, when used in the time domain analysis for the upward wave propagation from the bedrock back to ground surface, produces a surface motion in close agreement to the measured surface motion. This paper presents a procedure for evaluation of viscous damping from a given damping factors. This viscous damping successfully produces a surface motion in close agreement with the measured surface motion in a time domain analysis of upward wave propagation.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

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

Meeting Name

Fifth Conference

Publisher

Missouri University of Science and Technology

Publication Date

5-24-2010

Document Version

Final Version

Rights

© 2010 Missouri University of Science and Technology, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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May 24th, 12:00 AM May 29th, 12:00 AM

Viscous Damping for Time Domain Finite Element Analysis

San Diego, California

Earthquake waves propagate mainly in rock mass from hypocenter to the bedrock directly underneath a monitoring station. Then, it propagates as shear waves from the bedrock to a geophone, where the surface motion is measured. For a deposit with uniform soil layers of horizontal interfaces, one-dimensional finite element analysis can be performed to analyze the dynamic responses of a horizontal soil deposit. In an ideal dynamic soil-structure interaction analysis, seismic waves are propagated from the bedrock through soils and foundations, and then to structure. Thus, it is necessary to obtain the bedrock motion from a measured surface motion registered in geophone. Conventionally the process is called de-convolution. The de-convolution is treated as wave propagation in a frequency domain involving damping factor independent of motion velocity. The time-domain analysis is usually used in assessing the effects of soil-structure interaction. The time domain analysis requires the use of viscous damping proportional to motion velocity. Thus, it is necessary to device a method for the evaluation of viscous damping that, when used in the time domain analysis for the upward wave propagation from the bedrock back to ground surface, produces a surface motion in close agreement to the measured surface motion. This paper presents a procedure for evaluation of viscous damping from a given damping factors. This viscous damping successfully produces a surface motion in close agreement with the measured surface motion in a time domain analysis of upward wave propagation.