考虑板式支座滑移的中小跨度梁式桥振动台试验

基于汶川地震中小跨度梁式桥普遍出现的板式橡胶支座滑移典型震害，采用大比例全桥振动台试验手段探究了考虑板式支座滑移对该类桥梁抗震性能影响。以一座25m跨径的标准简支T梁桥为例，设计了1/4缩尺比的全桥试验模型，选取一条近场脉冲型实际地震动记录作为振动台试验输入，对不同墩梁横向约束体系的结构开展了一系列振动台试验研究。试验结果表明：①强震作用下板式橡胶支座与梁底间会出现摩擦滑移效应，从而在一定程度上对下部结构起到隔震作用；②在地震动较小时，常规横向混凝土挡块可以起到一定限位效果，但在强震作用下，随着板式橡胶支座开始发生滑移，混凝土挡块的限位效果逐渐减弱，同时混凝土挡块还会造成下部结构较大的地震损伤；③新型弹塑性挡块具有良好稳定的滞回耗能能力，可有效控制强震作用下墩梁间最大相对位移需求，减低其震后残余位移，同时弹塑性挡块的屈服还可避免下部结构造成严重地震损伤。

Shaking table tests of a short to medium-span girder bridge considering the sliding of laminated-rubber bearings

Based on the sliding of laminated-rubber bearings for short to medium-span girder bridges observed in Wenchuan earthquake, shaking table tests were used to investigate the effects of bearing sliding on the seismic performance of these types of bridges. A simply-supported, T-girder bridge with a span length of 25m was selected as the prototype, and a 1/4 scale bridge model was then designed and constructed just based on the bridge prototype. The bridge model was subjected to a near-fault earthquake record on the shaking tables. A series of shaking table tests were conducted on the bridge model with different types of superstructure-substructure connections. Results show that (1) The laminated-rubber bearings will slide along the girders under strong excitations, which to some extent provides isolation for the substructure; (2) Although concrete shear keys can restrain the girder displacements during small earthquakes, the restraining effect may diminish under strong earthquakes, especially when bearing sliding occurs; (3) Elastic-plastic retainers are proved to have powerful energy dissipation capacities. They can effectively control the maximum and residual seismic displacements of girders, and simultaneously, the yielding of retainers can prevent severe damages of substructures.