Testing and Modeling of Prestressed Isolators
Publication: Journal of Structural Engineering
Volume 131, Issue 6
Abstract
Isolation bearings experience tensile forces or uplift under certain conditions during seismic excitation. In general, this phenomenon is undesirable. This paper discusses an uplift prevention mechanism that uses prestress to develop sufficient compressive force on the isolator. A simplified theory of prestressed isolators is presented for three types of isolators, namely flat sliders, spherically shaped sliding bearings friction pendulum system (FPS), and elastomeric bearings. The behavior of prestressed isolators has been experimentally studied and presented. It has been observed that, consistent with the theory, the prestress has significant effects on the behavior of the prestressed isolators. The primary effect of prestress to increase the axial load on the isolators and prevent the uplift phenomenon was clearly observed in all three types of bearings tested in the study. The secondary effect of prestress to introduce additional lateral stiffness was also observed. While the additional axial load affects the behavior of elastomeric bearings, the effects were observed to be minor for the tested elastomeric bearings. In all cases of tested bearings, the experimental response could be predicted with sufficient accuracy by analytical means.
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Acknowledgments
Financial support for the work described herein was provided by the National Center for Earthquake Engineering Research, Project No. UNSPECIFIED95-5104A. SUSPA Spannbeton GmbH of Langenfeld, Germany supplied the fiberglass tendons.
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Information & Authors
Information
Published In
Journal of Structural Engineering
Volume 131 • Issue 6 • June 2005
Pages: 857 - 866
Copyright
© 2005 ASCE.
History
Received: May 28, 2003
Accepted: Jul 12, 2004
Published online: Jun 1, 2005
Published in print: Jun 2005
Notes
Note. Associate Editor: Sanj Malushte
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