地震作用下辅助墩对斜拉桥支座脱空的影响  

Effects of auxiliary piers on unseating of a cable-stayed bridge under earthquakes

作　　者：李永兴 易江 李建中[1] LI Yongxing;YI Jiang;LI Jianzhong(State Key Laboratory of Disaster Prevention For civil Engineering,Tongji University,Shanghai 200092,China)

机构地区：[1]同济大学土木工程防灾国家重点实验室

出　　处：《振动与冲击》2019年第15期95-102,108,共9页Journal of Vibration and Shock

基　　金：天津市自然科学基金(11JCYBJC27600)

摘　　要：强震中斜拉桥支座通常会受到主梁较强的上拉作用,有时甚至会发生支座脱空的现象。以一座实际的双塔斜拉桥为背景,研究了地震作用下斜拉桥的支座脱空现象以及辅助墩对斜拉桥支座脱空的影响。结果表明,在强震作用下该桥在过渡墩、辅助墩和主塔处均会出现支座脱空现象,具体表现为:主梁出现明显的竖向位移,当梁体与支座再次接触时产生较大的支座碰撞力;当斜拉桥两侧不设置辅助墩时,主梁的竖向位移和支座压力均较大;斜拉桥两侧各增设一辅助墩能够显著地降低地震作用下主梁的竖向位移及主梁与支座的碰撞力,但是随着辅助墩数量的持续增加,支座竖向反力和主梁竖向位移变化幅度不大;同时,提高辅助墩的成桥压力也能够在一定程度上降低支座脱空的不利影响。Supports of a cable-stayed bridge usually bear stronger up-tensile action of the main girder under strong earthquakes, and sometimes an unseating phenomenon happens. A 3-D nonlinear finite element model of a full bridge was established taking an actual double-tower cable-stayed bridge as background to study the unseating phenomenon of a cable-stayed bridge under earthquakes and effects of auxiliary piers on its unseating. The results showed that unseating phenomena of supports may happen at transition pier, auxiliary pier and main tower under strong earthquakes;unseating causes larger vertical displacement of main girder and larger impact forces when bridge body and supports contact again;when there are no auxiliary piers on both sides of cable-stayed bridge, the vertical displacement of main girder and vertical pressure of supports are larger;adding an auxiliary pier, respectively on both sides of cable-stayed bridge can significantly reduce the vertical displacement of main girder and vertical pounding force between main girder and supports;with increase in number of auxiliary piers, vertical displacement of main girder and vertical reaction force of supports change little;increasing bridge completion pressure of auxiliary pier can reduce adverse effects of unseating.

关 键 词：斜拉桥 抗震设计 支座脱空 辅助墩 

分 类 号：U442.5[建筑科学—桥梁与隧道工程]