Vertical vibration isolator having piecewise‐constant restoring force |
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| Authors: | Yoshikazu Araki Takehiko Asai Takeshi Masui |
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| Institution: | 1. Department of Architecture and Architectural Engineering, Kyoto University, Katsura, Kyoto 615‐8540, Japan;2. Department of Architecture, Kansai University, Suita, Osaka 564‐8680, Japan |
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| Abstract: | We present a vertical vibration isolator having a piecewise‐constant restoring force, which belongs to a class of passive and nonlinear vibration isolators. In vertical vibration isolation, direct use of low‐stiffness elements leads to unacceptably large deformations due to self‐weight. To overcome the difficulty, we apply a combination of constant‐force springs, each of which sustains a constant load regardless of its stretch. By arranging the constant‐force springs, so that the isolator has a piecewise‐constant restoring force, we alleviate the problem of the excessive deformation caused by self‐weight, provide stability at the static equilibrium state along with the self‐centering capability, and realize a large stroke while keeping the mechanism simple and compact. Further, we attempt to limit the response acceleration within a tolerance regardless of the frequency spectrum and the magnitude of earthquake ground motions. We demonstrate the effectiveness of the present isolator through shaking table tests and numerical simulations. Copyright © 2009 John Wiley & Sons, Ltd. |
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| Keywords: | vertical seismic isolation constant‐force spring shaking table experiment time history analysis |
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