Vibration characteristics change of a base-isolated building with semi-active dampers before, during, and after the 2011 Great East Japan earthquake

Maki Dan, Yuji Ishizawa, Sho Tanaka, Shuchi Nakahara, Shizuka Wakayama, Masayuki Kohiyama

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Structural vibration characteristics of a semi-active base-isolated building were investigated using seismic observation records including those of the 2011 Great East Japan earthquake (Tohoku earthquake). Three different types of analyses were conducted. First, we investigated the long-term changes in the natural frequencies and damping factors by using an ARX model and confirmed that the natural frequency of the superstructure decreased slightly after the main shock of the Tohoku earthquake. Second, we investigated short-term changes in the natural frequencies and damping factors during the main shock by using the N4SID method and observed different transition characteristics between the first and second modes. In the second mode, in which the superstructure response is most significant, the natural frequency changed depending on the response amplitude. In addition, at the beginning of the ground motion, the identified first natural frequency was high possibly as a result of sliding friction. Third, we compared the natural frequencies and damping factors between the conditions of a properly functional semi-active control system and a nonfunctional system, by using the records of the aftershocks of the Tohoku earthquake. However, we could not detect major differences because the response was probably influenced by sliding friction, which had a more significant effect on damping characteristics than did the semi-active dampers.

Original languageEnglish
Pages (from-to)889-913
Number of pages25
JournalEarthquake and Structures
Volume8
Issue number4
DOIs
Publication statusPublished - 2015 Jan 1

Keywords

  • 2011 great East Japan earthquake
  • Base isolation system
  • Semi-active damper
  • Structural response
  • System identification

ASJC Scopus subject areas

  • Civil and Structural Engineering

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