Mechanistic Model for Simulating Critical Behavior in Elastomeric Bearings
Publication: Journal of Structural Engineering
Volume 141, Issue 5
Abstract
When an elastomeric bearing is subjected to simultaneous vertical compressive load and lateral displacement, the shear force can pass through a maximum beyond which the bearing exhibits negative tangential horizontal stiffness and a condition of unstable equilibrium. This behavior has been experimentally demonstrated and has important implications on the stability and earthquake response of elastomeric seismic isolation bearings. Yet, analytical bearing models used for numerical earthquake simulation assume a positive second-slope stiffness irrespective of vertical load and/or bearing lateral displacement and therefore are unable to simulate the experimentally observed bearing behavior. Semiempirical bearing models have been developed and some of these models have been shown to simulate the influence of vertical load and lateral displacement on the shear force response with reasonable accuracy, however these models rely on a number of experimentally calibrated parameters, making them impractical for the purpose of design. An alternative approach to modeling the behavior of elastomeric bearings is explored in this study, which uses a series of vertical springs and a simple bilinear constitutive relationship to represent the rotational behavior of elastomeric bearings. The mechanistic bearing model, utilizing vertical springs, is shown to be capable of simulating the experimentally observed behavior with reasonable accuracy without relying on experimentally calibrated parameters.
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Acknowledgments
The authors gratefully acknowledge the support of the National Science Foundation through award number CMMI-1031362. Furthermore, the authors would like to acknowledge the author of Sanchez et al. (2013) for providing experimental data through the NEES Project Warehouse (https://nees.org/warehouse/project/571) and award number CMMI-1113275. Any opinions, findings, and recommendations expressed in this paper are those of the authors and do not necessarily reflect the views of the funding institutions.
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Published In
Journal of Structural Engineering
Volume 141 • Issue 5 • May 2015
Copyright
© 2014 American Society of Civil Engineers.
History
Received: Sep 26, 2013
Accepted: Mar 20, 2014
Published online: Jul 21, 2014
Discussion open until: Dec 21, 2014
Published in print: May 1, 2015
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