Abstract

SUMMARY: There is no consensus at the present time regarding an appropriate approach to model viscous damping in nonlinear time-history analysis of base-isolated buildings because of uncertainties associated with quantification of energy dissipation. Therefore, in this study, the effects of modeling viscous damping on the response of base-isolated reinforced concrete buildings subjected to earthquake ground motions are investigated. The test results of a reduced-scale three-story building previously tested on a shaking table are compared with three-dimensional finite element simulation results. The study is primarily focused on nonlinear direct-integration time-history analysis, where many different approaches of modeling viscous damping, developed within the framework of Rayleigh damping are considered. Nonlinear direct-integration time-history analysis results reveal that the damping ratio as well as the approach used to model damping has significant effects on the response, and quite importantly, a damping ratio of 1% is more appropriate in simulating the response than a damping ratio of 5%. It is shown that stiffness-proportional damping, where the coefficient multiplying the stiffness matrix is calculated from the frequency of the base-isolated building with the post-elastic stiffness of the isolation system, provides reasonable estimates of the peak response indicators, in addition to being able to capture the frequency content of the response very well. Furthermore, nonlinear modal time-history analyses using constant as well as frequency-dependent modal damping are also performed for comparison purposes. It was found that for nonlinear modal time-history analysis, frequency-dependent damping, where zero damping is assigned to the frequencies below the fundamental frequency of the superstructure for a fixed-base condition and 5% damping is assigned to all other frequencies, is more appropriate, than 5% constant damping. © 2013 John Wiley & Sons, Ltd.

Department(s)

Civil, Architectural and Environmental Engineering

Publication Status

Full Access

Keywords and Phrases

Base isolation; Nonlinear analysis; Rayleigh damping; Shaking table test

International Standard Serial Number (ISSN)

1096-9845; 0098-8847

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2024 Wiley, All rights reserved.

Publication Date

01 Jan 2013

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