Time-variant modal parameters and response behavior of a base-isolated building tested on a shake table

Rodrigo Astroza; Gonzalo Gutiérrez; Christian Repenning; Francisco Hernández

doi:10.1193/032817EQS054M

Time-variant modal parameters and response behavior of a base-isolated building tested on a shake table

Rodrigo Astroza, Gonzalo Gutiérrez, Christian Repenning, Francisco Hernández

Research output: Contribution to journal › Article › peer-review

12 Scopus citations

Abstract

This paper presents the identification of the instantaneous modal properties and the experimental response of a full-scale, five-story base-isolated RC building tested on a shake table. A suite of earthquake motions of various intensities was applied to the building to progressively increase the seismic demand. The deterministic-stochastic subspace identification method is employed to estimate the variations of the modal properties of the building by employing a short-time windowing approach. The changes of the modal parameters during the seismic motions are tracked and analyzed. Observed and measured responses of the structure are analyzed and correlated with the variation of the identified modal parameters. 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 language	English
Pages (from-to)	121-143
Number of pages	23
Journal	Earthquake Spectra
Volume	34
Issue number	1
DOIs	https://doi.org/10.1193/032817EQS054M
State	Published - Feb 2018

Bibliographical note

Funding Information:
The authors acknowledge the access to the “Full-Scale Structural and Nonstructural Building System Performance during Earthquakes” project database (DOI: 10.4231/ D38W38349) though the NEES Project Warehouse (https://nees.org/warehouse/project/ 722). The authors are 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 Fondo de Ayuda a la Investigación (FAI) and from the Chilean National Commission for Scientific and Technological Research (CONICYT), FONDECYT project No. 11160009.

Publisher Copyright:
© 2018 Earthquake Engineering Research Institute.

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10.1193/032817EQS054M

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title = "Time-variant modal parameters and response behavior of a base-isolated building tested on a shake table",

abstract = "This paper presents the identification of the instantaneous modal properties and the experimental response of a full-scale, five-story base-isolated RC building tested on a shake table. A suite of earthquake motions of various intensities was applied to the building to progressively increase the seismic demand. The deterministic-stochastic subspace identification method is employed to estimate the variations of the modal properties of the building by employing a short-time windowing approach. The changes of the modal parameters during the seismic motions are tracked and analyzed. Observed and measured responses of the structure are analyzed and correlated with the variation of the identified modal parameters. 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.",

author = "Rodrigo Astroza and Gonzalo Guti{\'e}rrez and Christian Repenning and Francisco Hern{\'a}ndez",

note = "Funding Information: The authors acknowledge the access to the “Full-Scale Structural and Nonstructural Building System Performance during Earthquakes” project database (DOI: 10.4231/ D38W38349) though the NEES Project Warehouse (https://nees.org/warehouse/project/ 722). The authors are very grateful to Professors Tara C. Hutchinson, Joel P. Conte, and Jos{\'e} 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 Fondo de Ayuda a la Investigaci{\'o}n (FAI) and from the Chilean National Commission for Scientific and Technological Research (CONICYT), FONDECYT project No. 11160009. Publisher Copyright: {\textcopyright} 2018 Earthquake Engineering Research Institute.",

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N2 - This paper presents the identification of the instantaneous modal properties and the experimental response of a full-scale, five-story base-isolated RC building tested on a shake table. A suite of earthquake motions of various intensities was applied to the building to progressively increase the seismic demand. The deterministic-stochastic subspace identification method is employed to estimate the variations of the modal properties of the building by employing a short-time windowing approach. The changes of the modal parameters during the seismic motions are tracked and analyzed. Observed and measured responses of the structure are analyzed and correlated with the variation of the identified modal parameters. 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.

AB - This paper presents the identification of the instantaneous modal properties and the experimental response of a full-scale, five-story base-isolated RC building tested on a shake table. A suite of earthquake motions of various intensities was applied to the building to progressively increase the seismic demand. The deterministic-stochastic subspace identification method is employed to estimate the variations of the modal properties of the building by employing a short-time windowing approach. The changes of the modal parameters during the seismic motions are tracked and analyzed. Observed and measured responses of the structure are analyzed and correlated with the variation of the identified modal parameters. 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.

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Time-variant modal parameters and response behavior of a base-isolated building tested on a shake table

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