Seismic Response of Isolated Bridges
Publication: Journal of Bridge Engineering
Volume 9, Issue 2
Abstract
The seismic response of bridges seismically isolated by lead-rubber bearings (L-RB) to bidirectional earthquake excitation (i.e., two horizontal components) is presented in this paper. The force-deformation behavior of L-RB is considered as bilinear, and the interaction between the restoring forces in two orthogonal horizontal directions is duly considered in the response analysis. The specific purpose of the study is to assess the effects of seismic isolation on the peak response of the bridges, and to investigate the effects of the bidirectional interaction of restoring forces of isolation bearings. The seismic response of the lumped mass model of continuous span isolated bridges is obtained by solving the governing equations of motion in the incremental form using an iterative step-by-step method. To study the effectiveness of L-RB, the seismic response of isolated bridges is compared with the response of corresponding nonisolated bridges (i.e., bridges without isolation devices). A comparison of the response of the isolated bridges obtained by considering and ignoring the bidirectional interaction of bearing forces is made under important parametric variation. The important parameters included are the flexibility of the bridge piers and the stiffness and yield strength of the L-RB. The results show that the bidirectional interaction of the restoring forces of the L-RB has considerable effects on the seismic response of the isolated bridges. If these interaction effects are ignored, then the peak bearing displacements are underestimated, which can be crucial from the design point of view.
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Information & Authors
Information
Published In
Journal of Bridge Engineering
Volume 9 • Issue 2 • March 2004
Pages: 156 - 166
Copyright
Copyright © 2004 American Society of Civil Engineers.
History
Received: Jun 4, 2001
Accepted: Nov 12, 2002
Published online: Feb 19, 2004
Published in print: Mar 2004
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