桥梁板式橡胶支座剪切破坏及摩擦滑移性能试验研究

Experiment of Shear Failure and Friction Sliding Performance of Elastomeric Bearings of Bridges

为充分探明桥梁板式橡胶支座的极限剪切破坏状态及支座摩擦滑移特性,对板式橡胶支座开展循环往复荷载试验。分析单侧摩擦滑移和两端锚固的板式橡胶支座的抗震性能,并与铅芯橡胶支座进行对比,同时分析竖向荷载对板式橡胶支座摩擦滑移性能的影响。结果表明:(1)两端锚固的板式橡胶支座极限剪切变形可达300%~400%,破坏以橡胶层断裂为主,支座剪切耗能能力较弱,滞回曲线呈狭长带状分布;(2)单侧摩擦滑移的板式橡胶支座单循环最大耗能可以达到铅芯橡胶支座的126%,形成类似铅芯橡胶支座的耗能能力,且随着位移量的增加,不断消耗能量;在达到相同的等效剪切应变时,单侧摩擦滑移的板式橡胶支座的实际剪切变形量小于两端固定的支座,延性性能更为优越;(3)增大竖向压力将导致支座的剪切变形增大,支座滑移距离减小,支座的滑移摩擦系数与竖向压力呈反比例关系,而竖向压力对支座滑移后的等效刚度影响较小;(4)可采用能够考虑竖向压力和滑移摩擦系数的双线性弹塑性分析模型模拟板式橡胶支座在地震过程中的摩擦滑移。

To fully ascertain the ultimate shear failure state and the friction sliding performance of laminated elastomeric bearings used in bridges,a series of cyclic loading tests were conducted.The seismic performance of the bearings with two fixed plates and with unilateral friction sliding was analyzed and compared with a lead rubber bearing(LRB).At the same time,the effect of vertical load on the friction sliding of the bearings was analyzed.The results show that:(1)The ultimate shear deformation of the elastomeric bearings with two fixed plates reaches 300%to 400%of the rubber layer thickness,with the damage mainly caused by the rubber layer fracture,resulting in weak energy dissipation capacity of the bearings,and narrow zonal shape of the hysteresis curve.(2)The elastomeric bearings with unilateral friction sliding show a similar energy dissipation capacity compared to the LRB,with maximum energy dissipation in a single cycle up to 126%of the LRB’s maximum energy dissipation.With the increase of sliding distance,the dissipated energy continuously increases.Under the same equivalent shear strain,the actual shear deformation of the bearings with unilateral frictional sliding is less than the common bearings,which means better ductility.(3)The increase of the vertical pressure will increase the shear deformation of bearings and decrease the sliding distance.The sliding friction coefficient of the bearing is inversely proportional to the vertical pressure and the influence of the vertical pressure is minor on the equivalent stiffness of the bearings after sliding.(4)Bilinear elastoplastic analysis model considering vertical pressure and sliding friction coefficient is proposed to simulate the frictional sliding of elastomeric bearings during earthquake.