Property Modification Factors for Seismically Isolated Bridges
Publication: Journal of Bridge Engineering
Volume 11, Issue 3
Abstract
An analytical study investigating how changes in the mechanical properties of individual seismic isolators affect the response of isolated bridge structures subjected to earthquake excitation is summarized. Nonlinear response-history analyses are conducted utilizing bins of recorded earthquake ground motion pairs. Twenty bilinear isolation systems are considered so that the results of this study are broadly applicable to the design of seismic isolation systems in the United States. Variations in the mechanical properties are considered using a property modification factor, , to modify the appropriate bilinear isolator parameter. The results of analyses considering nominal and modified isolation systems are used to systematically identify changes in system response as a function of the property modification factor. These results are used to determine threshold values of the property modification factor that should aid engineers in the preliminary design and assessment of an isolation system prior to performing the bounding analysis now required by bridge and building design codes.
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Acknowledgments
The writers gratefully acknowledge the financial support of the Multidisciplinary Center for Earthquake Engineering Research and the Federal Highway Administration through Task D1.4 of the Federal Highway Administration Contract DTFH 61-98-C-0094. The authors also wish to thank Professor Eduardo Miranda of Stanford University for contributing ground motion records for use in this study. The opinions expressed in this paper are those of the writers and do not reflect the opinions of the Multidisciplinary Center for Earthquake Engineering Research or the Federal Highway Administration. No guarantee regarding the results, findings, and recommendations are offered by either the Multidisciplinary Center for Earthquake Engineering Research or the Federal Highway Administration.
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Information & Authors
Information
Published In
Journal of Bridge Engineering
Volume 11 • Issue 3 • May 2006
Pages: 371 - 377
Copyright
© 2006 ASCE.
History
Received: Nov 30, 2004
Accepted: May 2, 2005
Published online: May 1, 2006
Published in print: May 2006
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