滑动支座摩擦效应对连续梁桥地震响应影响

Influence of Friction Effect of Sliding Bearings on Seismic Response of Continuous Beam Bridge

摘要:

以1座跨度为（55+4×90+55） m的预应力混凝土变截面连续梁桥为研究对象，采用ANSYS软件建立桥梁动力分析模型.选取3条人工地震波作为地震动输入，基于动力非线性分析方法，考虑摩擦效应，分析盆式橡胶支座连续梁桥非固定墩的地震响应和支座的滞回性能，并与未考虑摩擦效应的地震响应进行比较.结果表明：非固定墩处的盆式橡胶支座在地震作用下形成了规则、饱满的滞回曲线，形状近似为矩形；相对未考虑盆式橡胶支座摩擦效应的模型，考虑支座滑动后，固定墩墩底顺桥向弯矩、剪力分别降低了25.91%、27.41%，固定墩墩顶顺桥向位移和非固定墩墩梁相对位移分别降低了26.15%、25.59%；对于多跨长联连续梁桥，滑动支座数量多且反力大，若不考虑滑动支座的摩擦耗能，桥梁结构地震响应结果偏大，抗震设计偏于保守.

关键词:桥梁工程; 连续梁桥; 非线性时程分析法; 盆式橡胶支座; 摩擦效应; 地震响应; 有限元法

Abstract:

A variable crosssection prestressed concrete continuous girder bridge with a span of (55+4×90+55) m as the research object was analyzed, and the dynamic analysis model of the bridge was established by using the software ANSYS. Three artificial seismic waves were selected as seismic input. Based on dynamic nonlinear analysis method, the seismic response of the bridge and the hysteresis performance of the bearing considering friction effect for nonbrake piers were analyzed. Then, the seismic respose of the bridge considering friction effect was compared with that without considering friction effect. The results indicate that the basin rubber bearing at nonbrake pier has a regular and full hysteresis curve under seismic action, and the shape of the hysteresis curve is approximately rectangular. After considering the friction effect of the basin rubber bearing, the longitudinal bending moment and the shear force were reduced by 25.91% and 27.41% respectively at the bottom of nonbrake pier. The longitudinal displacement at the top of brake pier and the pierbeam relative displacement of nonbrake pier were reduced by 26.15% and 25.59% respectively. If the friction energy dissipation of sliding bearings is not considered for the multispan and longunit continuous beam bridge with multiple sliding bearings whose reaction force is large, the seismic response of bridge structure will be larger and the seismic design will be too conservative.

Key words:bridge engineering; continuous girder bridge; nonlinear time history analysis; basin rubber bearings; friction effect; seismic response; finite element method