支座摩擦效应对基于黏滞阻尼器的连续梁桥地震反应的影响

Influence of bearing friction effect to seismic response of continuous beam bridge based on viscous dampers

依托某基于黏滞阻尼器进行减震设计的城际铁路连续梁桥为工程背景,开展多遇及罕遇地震下支座摩擦效应对其地震反应的影响分析。采用Midas软件建立全桥有限元模型,纵桥向输入三条安评波进行非线性时程反应分析,从墩底内力、墩顶位移及墩梁相对位移三个方面对其影响进行评价。结果表明:支座摩擦对减震设计桥梁的影响不同于传统抗震设计桥梁:①多遇地震作用下,考虑支座摩擦作用会增大结构的墩底内力,主要原因是阻尼器的设置使支座处于静摩擦状态,不但无法有效滑动耗能反而增加了墩梁连接刚度;②罕遇地震作用下,支座摩擦作用降低固定墩的墩底内力,滑动支座摩擦对全桥中较高活动墩墩梁相对位移的敏感程度高于较矮的桥墩;③滑动支座对基于黏滞阻尼器减震设计的连续梁桥在多遇和罕遇地震作用下地震反应的影响机理为增加连接刚度和耗散能量。

On the basis of the engineering background of an intercity railway continuous girder bridge based on the damping design of a viscous damper,the influence of friction effect on the seismic response of the bearing is carried out under frequent and rare earthquake.Midas software is used to establish the whole bridge finite element model,the longitudinal bridge is inputted with three safety assessment wave,the nonlinear time history analysis is carried out,and its influence from the three aspects of internal force of the pier,the top displacement and the relative displacement of the pier and beam is evaluated.The results show that:the influence of isolation design bridge is different from that of traditional aseismic design bridge:①under multiple earthquakes,considering the friction of the bearing will increase the internal force of the pier,the main reason is that the damper is set so that the bearing is in the static friction state,not only can not effectively slide the energy dissipation but increase the pier beam connection stiffness;②under rare earthquakes,the bearing friction reduces the internal force of the pier base,and the friction of the movable bearing is more sensitive to the relative displacement of the piers and abutments of the bridge than the shorter piers;③the effect of the active bearing on the seismic response of continuous girder bridges based on the damping design of viscous dampers under multiple and rare earthquakes is to increase the connection stiffness and dissipation energy.