Seismic base isolation by nonlinear mode localization

Y. Wang, D. M. McFarland, A. F. Vakakis, Lawrence Bergman

Research output: Contribution to journalArticlepeer-review

Abstract

In this paper the performance of a nonlinear base-isolation system comprised of a nonlinearly sprung subfoundation tuned in a 1:1 internal resonance to a flexible mode of the linear primary structure to be isolated is examined. The application of nonlinear localization to seismic isolation distinguishes this study from other base-isolation studies in the literature. Under the condition of third-order smooth stiffness nonlinearity it is shown that a localized nonlinear normal mode (NNM) is induced in the system which confines energy to the subfoundation and away from the primary or main structure. This is followed by a numerical analysis wherein the smooth nonlinearity is replaced by clearance nonlinearity and the system is excited by ground motions representing near-field seismic events. The performance of the nonlinear system is compared with that of the corresponding linear system through simulation and the sensitivity of the isolation system to several design parameters is analyzed. These simulations confirm the existence of the localized NNM and show that the introduction of simple clearance nonlinearity significantly reduces the seismic energy transmitted to the main structure resulting in significant attenuation in the response.

Original languageEnglish (US)
Pages (from-to)387-414
Number of pages28
JournalArchive of Applied Mechanics
Volume74
Issue number5-6
DOIs
StatePublished - Mar 1 2005

Keywords

  • Base isolation
  • Nonlinear localization
  • Nonlinear normal modes

ASJC Scopus subject areas

  • Mechanical Engineering

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