Time evolution of the modal parameters of a five-story building using strong motion data

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Abstract

This paper presents the identification of the time-variant modal properties of a full-scale fivestory RC building tested on a shake table. The building was tested under fixed-base (FB) and base-isolated (BI) configurations and was subjected to a suite of earthquake motions of various intensities. The deterministic-stochastic subspace identification method is employed to estimate the variations of the modal properties of the BI building during the seismic tests by employing a short-time windowing approach. The changes of the modal parameters are tracked, analyzed, and compared to those previously identified from ambient vibrations data and low-amplitude whitenoise base excitation tests. In addition, observed and measured responses of the structure are studied and correlated with the variation of the identified modal parameters. For the base-isolated configuration, the nonlinear behavior of the isolators generates the variation of the identified natural frequencies and equivalent damping ratios of the building, which change in agreement with the input motion intensity. A high correlation between the effective stiffness of the isolators and the instantaneous frequency of the first mode is found. The effective damping ratio of the isolation system and the instantaneous damping ratio of the fundamental mode of the building are highly correlated.

Original languageEnglish
Title of host publication11th National Conference on Earthquake Engineering 2018, NCEE 2018
Subtitle of host publicationIntegrating Science, Engineering, and Policy
PublisherEarthquake Engineering Research Institute
Pages6155-6164
Number of pages10
ISBN (Electronic)9781510873254
StatePublished - 2018
Event11th National Conference on Earthquake Engineering 2018: Integrating Science, Engineering, and Policy, NCEE 2018 - Los Angeles, United States
Duration: 25 Jun 201829 Jun 2018

Publication series

Name11th National Conference on Earthquake Engineering 2018, NCEE 2018: Integrating Science, Engineering, and Policy
Volume10

Conference

Conference11th National Conference on Earthquake Engineering 2018: Integrating Science, Engineering, and Policy, NCEE 2018
Country/TerritoryUnited States
CityLos Angeles
Period25/06/1829/06/18

Bibliographical note

Funding Information:
The author is very grateful to Professors Tara C. Hutchinson, Joel P. Conte, and José I. Restrepo from the University of California, San Diego for making these data available. R. Astroza acknowledges the financial support from the Universidad de los Andes, Chile through the research grant FAI and from the Chilean National Commission for Scientific and Technological Research (CONICYT), FONDECYT project No. 11160009.

Funding Information:
The author is very grateful to Professors Tara C. Hutchinson, Joel P. Conte, and Jos? I. Restrepo from the University of California, San Diego for making these data available. R. Astroza acknowledges the financial support from the Universidad de los Andes, Chile through the research grant FAI and from the Chilean National Commission for Scientific and Technological Research (CONICYT), FONDECYT project No. 11160009.

Publisher Copyright:
Copyright © 2018 Earthquake Engineering Research Institute. All rights reserved.

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