Seismic isolation of cable‐stayed bridges for near‐field ground motions
Seismic isolation of cable‐stayed bridges for near‐field ground motions
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DOI：
10.1002/eqe.318
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发表时间：
2003-11
影响因子：
4.5
通讯作者：
M. Wesolowsky;John C. Wilson
中科院分区：
文献类型：
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作者：
M. Wesolowsky;John C. Wilson
本研究考察了使用隔震对斜拉桥在近场地震地面运动下的地震反应产生积极影响的有效性。在近场地震地面运动中，在许多斜拉桥具有显著结构响应模式的情况下，长周期会出现大振幅谱加速度。这些因素的组合可能导致塔架加速度和基座剪切。在本研究中，对三座斜拉桥的铅橡胶支座隔震器进行了建模，并对每座桥的三种隔震情况进行了检查。采用三维时程分析方法，对9个隔离桥结构和3个非隔离桥结构进行了近场地震地面运动分析。引入少量的隔离被证明对减少地震加速度和力非常有益，同时只产生适度的结构位移增加。通过进一步延长结构的寿命来继续增加隔离量的边际效益很低，因为结构力和加速度以递减的速度减少，而结构位移则大幅增加。在几乎所有情况下，隔离桥的基础剪切量减少了至少50，有些情况下减少了多达80个，单个近场记录显示出从一个记录到下一个记录的巨大变化，平均变异系数高达50，评估近场地面运动的特征，用于斜拉桥隔离设计。版权所有©2003 John Wiley & Sons， Ltd
This study examines the efficacy of using seismic isolation to favorably influence the seismic response of cable‐stayed bridges subjected to near‐field earthquake ground motions. In near‐field earthquake ground motions, large amplitude spectral accelerations can occur at long periods where many cable‐stayed bridges have significant structural response modes. This combination of factors can result in large tower accelerations and base shears. In this study, lead–rubber bearing seismic isolators were modeled for three cable‐stayed bridges, and three cases of isolation were examined for each bridge. The nine isolated bridge configurations, plus three non‐isolated configurations as references, were subjected to near‐field earthquake ground motions using three‐dimensional time‐history analyses. Introduction of a small amount of isolation is shown to be very beneficial in reducing seismic accelerations and forces while at the same time producing only a modest increase in the structural displacements. There is a low marginal benefit to continue to increase the amount of isolation by further lengthening the period of the structure because structural forces and accelerations reduce at a diminishing rate whereas structural displacements increase substantially. In virtually all cases the base shears in the isolated bridges were reduced by at least 50several instances by up to 80individual near‐field records showed large variability from one record to the next, with coefficients of variation about the mean as large as 50assessing the characteristics of near‐field ground motion for use in isolation design of cable‐stayed bridges. Copyright © 2003 John Wiley & Sons, Ltd.