关键词: 斜拉桥, 强地震动, 抗震性能, 地震反应, 线性能力需求比, 非线性弹塑性单元

Abstract:

This paper deals with the seismic performance of cable-stayed bridges subjected to longitudinal strong ground motions,with one typical medium-span cable-stayed bridge as the research object. In the investigation,the linear seismic capacity-to-demand ratio of the bridge is determined,based on which different types of nonlinear electroplastic elements are introduced to reveal the plastic behaviors of the main bridge components as well as their effects on the whole-bridge seismic response. The results show that ( 1) under strong ground motions,the plastic behaviors of the bridge tower and the piers correlate with not only the characteristics but also the intensity of seismic waves; ( 2) the bridge tower may yield before the auxiliary and the side piers do; and ( 3) the yielding of the bridge tower results in a significant reduction of seismic-induced moment of tower columns. Therefore,in strong earthquakes,it is necessary to take into consideration the nonlinear seismic response of the bridge tower and its effect on the seismic performance of the whole bridge. Meanwhile,in current practical design,the bridge tower and piers may still conserve certain plasticity margin under longitudinal strong ground motions.

Key words: cable-stayed bridge, strong ground motion, seismic performance, seismic response, linear seismic capacity-to-demand ratio, nonlinear elastoplastic element