Experimental Investigation of Elastomeric Isolation Bearings with Flexible Supporting Columns
Publication: Journal of Structural Engineering
Volume 143, Issue 7
Abstract
In an effort to mitigate major costs associated with isolation systems, especially in retrofit applications, isolation bearings may be placed on the tops of columns. In this configuration, a seismic gap and additional rigid diaphragm are no longer necessary, and excavation and foundation work may potentially be avoided in retrofit applications; however, columns under the isolation layer may not provide rigid boundary conditions, resulting in bearing end plates not remaining parallel. To investigate the effects of flexible columns in a column-top isolation system with elastomeric bearings, quasi-static cyclic testing of bearing-column subassemblies were conducted. Findings show that flexible end conditions can significantly reduce the lateral stiffness of elastomeric bearings. A simple analytical stiffness matrix is derived for bearings consisting of translational and rotational degrees of freedom at both end plates and is compared against experimental results. The simple model compares well for initial behavior but diverges from experimental results with larger end-plate rotations; however, when calibrated nonlinear material properties are included, the model performs well at capturing the behavior of elastomeric bearings when subjected to partially restrained boundary conditions.
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Acknowledgments
Financial support for this study was provided by the National Sciences and Engineering Research Council (NSERC). The authors would like to thank Richard Darlington, Paul Heerema, and Kent Wheeler for their assistance in the design and construction of the experimental setup.
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©2017 American Society of Civil Engineers.
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Received: Apr 12, 2016
Accepted: Dec 20, 2016
Published online: Mar 15, 2017
Published in print: Jul 1, 2017
Discussion open until: Aug 15, 2017
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