Location

Arlington, Virginia

Session Start Date

8-11-2008

Session End Date

8-16-2008

Abstract

This paper aims to determine the dependence of seismic response on the shape of the time-domain filter used in the stochastic method of ground motion prediction. Brune’s single-corner point source model was used in conjunction with the current attenuation relationships developed for hard rock sites in the Eastern North America (ENA) to obtain the target ground motion spectrum. A total of three hundred synthetic accelerograms were generated by filtering the Gaussian white noise with exponential, triangular and trapezoidal windows. For each accelerogram, displacement response of the Duffing’s oscillator was calculated, and its average amplitude spectrum was constructed in the joint time-frequency domain using Mexican hat wavelets. This procedure was repeated for three levels of nonlinearity. Among the three shapes examined, the trapezoidal window was associated with longer durations of sustained energy, thereby increasing the level of the expected damage. The dependence of the seismic response to the particular filter shape became more pronounced with increased levels of nonlinearity. This study concludes that ground motions with the same Fourier Amplitude Spectrum could cause substantially different levels of seismic damage on the same structure, depending on the time-frequency localization of the energy imparted to the structure.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conference on Case Histories in Geotechnical Engineering

Meeting Name

Sixth Conference

Publisher

Missouri University of Science and Technology

Publication Date

8-11-2008

Document Version

Final Version

Rights

© 2008 Missouri University of Science and Technology, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Generating Realistic Ground Motions for Nonlinear Seismic Hazard Analysis — An Application to Hard Rock Sites in Eastern North America

Arlington, Virginia

This paper aims to determine the dependence of seismic response on the shape of the time-domain filter used in the stochastic method of ground motion prediction. Brune’s single-corner point source model was used in conjunction with the current attenuation relationships developed for hard rock sites in the Eastern North America (ENA) to obtain the target ground motion spectrum. A total of three hundred synthetic accelerograms were generated by filtering the Gaussian white noise with exponential, triangular and trapezoidal windows. For each accelerogram, displacement response of the Duffing’s oscillator was calculated, and its average amplitude spectrum was constructed in the joint time-frequency domain using Mexican hat wavelets. This procedure was repeated for three levels of nonlinearity. Among the three shapes examined, the trapezoidal window was associated with longer durations of sustained energy, thereby increasing the level of the expected damage. The dependence of the seismic response to the particular filter shape became more pronounced with increased levels of nonlinearity. This study concludes that ground motions with the same Fourier Amplitude Spectrum could cause substantially different levels of seismic damage on the same structure, depending on the time-frequency localization of the energy imparted to the structure.