重心高度对不同体系斜拉桥地震响应特性影响研究

Study of Seismic Response Characteristics of Gravity Center's Height to Different Structure System Cable-Stayed Bridge

针对目前关于重心高度对不同体系斜拉桥地震响应特性的认识还不够全面这一现状,以某斜拉桥为例,分别建立飘浮体系和纵向固结体系有限元模型,通过改变下塔柱高度的方式改变斜拉桥的重心高度,分析重心高度对斜拉桥地震响应的影响规律。研究表明:随着斜拉桥重心高度的变化,存在纵向固结体系中塔底截面弯矩和剪力响应同时小于飘浮体系的情况;当重心较低时,纵向固结体系下塔底截面的剪力响应大于飘浮体系的剪力响应,但下塔底截面弯矩响应却一直小于飘浮体系的弯矩响应;而对于关键点位移响应,纵向固结体系明显小于飘浮体系,重心高度越低,这种优势越明显。因此针对具体斜拉桥应具体分析,以便选择合理的结构体系,提高其整体抗震性能。

Currently with regard to the cable-stayed bridge of different structure systems, the understanding of gravity center height to seismic response characteristics is not comprehensive. Taking a cable--stayed bridge as an example, the FEM modeling of longitudinal floating system and consolidation system are built. With changing the height of lower tower, the effect laws of the gravity center height to seismic response are studied. The results show that, along with the change of the gravity center height, to the shear and moment response of the middle pylon bottom, the longitudinal consolidation system is lower than longitudinal floating system. To the force response of low pylon bottom, when the gravity center height is low, shear response of longitudinal consolidation system is greater than that of longitudinal floating system, but moment response is lower than that of longitudinal floating system. To the displacement response of key points, longitudinal consolidation system is superior to floating system. The lower the gravity center height becomes, the more obvious the advantage is. As a conclusion, only when concrete cable-stayed bridge is specifically analyzed, that can rational structure system be chosen to improve its overall seismic performance.