Behavior of Bidirectional Spring Unit in Isolated Floor Systems
Publication: Journal of Structural Engineering
Volume 136, Issue 8
Abstract
To investigate the mechanical behavior of bidirectional spring units used as isolators in a kind of isolated floor system, three types of characterization tests were conducted—from spring components alone to the complete spring unit in its implemented configuration. The test results show that the behavior of the springs and spring units is stable when subjected to cyclic repeated motions, and is not sensitive to the velocity of motion. The hysteretic behavior of the spring units was found to be unconventional, with bilinear and different ascending (loading) and descending (unloading) branches. Based on the experimental behavior, a physical model was developed to replicate the unique behavior of such bidirectional spring units. Good agreement was found from the comparison between the results from the physical model and the corresponding tests. Finally, a sensitivity study, with respect to the model’s four primary defining parameters, shows that this physical model is more sensitive to the sliding friction coefficient between the spring cable and the bushing in the spring unit than to the other three parameters.
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Acknowledgments
This work was supported in whole by the Earthquake Engineering Research Centers Program of the National Science Foundation under Award No. NSFECC-9701471 to the Multidisciplinary Center for Earthquake Engineering Research. The bidirectional spring unit is a proprietary device patented by Dynamic Isolation Systems, Inc. (DIS). The floor isolation system and the springs were provided by DIS for this study. Any opinions, findings, conclusions, and recommendations presented in this paper are those of the writers and do not necessarily reflect the views of the sponsors.
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Information
Published In
Journal of Structural Engineering
Volume 136 • Issue 8 • August 2010
Pages: 944 - 952
Copyright
© 2010 ASCE.
History
Received: Dec 2, 2008
Accepted: Jan 9, 2010
Published online: Jan 13, 2010
Published in print: Aug 2010
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