Equivalent Modal Damping of Short-Span Bridges Subjected to Strong Motion
Publication: Journal of Bridge Engineering
Volume 16, Issue 2
Abstract
In this paper four different methods are investigated for estimating the equivalent modal damping ratios of a short-span bridge under strong ground motion by considering the energy dissipation at the boundary. The Painter Street Overcrossing (PSO) is investigated because of seismic data availability. Computed responses using the response-spectrum method with the equivalent damping ratios estimates are compared with the recorded responses. The results show that the four methods provide reasonable estimation of equivalent modal damping ratios and that neglecting off-diagonal elements in the damping matrix is the most efficient and practical method. The equivalent damping ratio of the PSO was nearly 25% under an earthquake with peak ground acceleration of , which is much higher than the conventional assumption of 5%.
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Acknowledgments
The study presented in this paper was supported by the California Department of Transportation (Caltrans) under Grant No. CADOT59A0495, the NaeKyung Engineering Company, and the Infra-Structures Assessment Research Center (ISARC) funded by the Ministry of Land, Transport, and Maritime Affairs, Korea. The writers would like to thank Dr. Joseph Penzien, Professor Emeritus at University of California, Berkeley, and Mr. Mike Keever and Mr. Lihong Sheng of Caltrans for their guidance and support.
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Information & Authors
Information
Published In
Journal of Bridge Engineering
Volume 16 • Issue 2 • March 2011
Pages: 316 - 323
Copyright
© 2011 American Society of Civil Engineers.
History
Received: Apr 17, 2009
Accepted: Jun 9, 2010
Published online: Jun 15, 2010
Published in print: Mar 1, 2011
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