脉冲型地震动作用下双薄壁墩参数对矮塔斜拉桥地震反应的影响

Influence of Double Thin-wall Parameters on Seismic Responses of Extradosed Cable-stayed Bridge Under Pulse Ground Motions

以某双塔三跨矮塔斜拉桥为背景,通过非线性分析探究脉冲型地震动下双薄壁墩的几何参数对矮塔斜拉桥桥墩地震反应影响规律,为抗震设计中双薄壁墩几何参数取值提供一些参考依据。结果表明:壁厚主要影响结构基频,双肢中心距主要影响结构高阶频率,墩高同时影响结构基频和高阶频率;相比于远场无脉冲地震动,横向脉冲型地震作用下墩的内力反应增幅超过20%,纵向脉冲型地震作用下墩的内力反应增幅超过30%;远场地震动及近断层地震动作用下,墩参数在工程合理取值范围内,减小双薄壁墩的厚度、增加墩高能减小桥墩地震反应;双肢中心距对墩的地震反应影响很小,减小壁厚能提高墩的延性,双肢中心距和墩高不影响桥墩延性。

Taking a double tower three span low tower cable-stayed bridge as the background,this paper explores the influence law of the geometric parameters of double thin-walled piers on the seismic response of low tower cable-stayed bridge piers under impulse ground motion through nonlinear analysis,so as to provide some reference basis for the geometric parameters of double thin-walled piers in seismic design.The results show that the wall thickness mainly affects the fundamental frequency of the structure,the center distance of the two legs mainly affects the high-order frequency of the structure,and the pier height affects both the fundamental frequency and the high-order frequency of the structure;Compared with the far-field non pulse ground motion,the internal force response of the pier under the action of transverse pulse earthquake increases by more than 20%,and the internal force response of the pier under the action of longitudinal pulse earthquake increases by more than 30%;Under the action of far-field earthquake and near fault ground motion,the pier parameters are within the reasonable value range of the project,reducing the thickness of the double thin-walled pier,increasing the high energy of the pier and reducing the seismic response of the pier;The center distance of the two legs has little effect on the seismic response of the pier.Reducing the wall thickness can improve the ductility of the pier,and the center distance of the two legs and the height of the pier do not affect the ductility of the pier.