罕遇地震作用下高速铁路简支梁桥抗震性能分析

简支梁桥在高速铁路中占到了极高的比例,其抗震性能值得深入研究。结合西部高速铁路中典型的简支梁桥结构形式,建立不同墩高的高速铁路多跨简支梁桥的全桥空间分析模型,在模型中采用纤维单元模拟桥墩,并对固定支座锚固螺栓在罕遇地震作用下可能被剪断的力学特性予以适当的模拟,采用非线性时程方法分析高烈度地震区内该类桥梁在罕遇地震作用下的弹塑性地震响应,讨论该桥的损伤模式。分析结果表明:相比纵桥向地震作用,墩高20 m以内的高速铁路大跨度简支梁桥在横桥向地震作用下的桥墩损伤程度更大;整体看来桥墩具有较好的抗震性能,而合理控制支座锚固螺栓被剪断后主梁所产生的较大位移将成为铁路简支梁桥抗震设计中的重点。

Study on Seismic Performance of High-speed Railway Simply-supported Girder Bridge under Strong Earthquake Motion

The simply-supported girder bridges cover a vast majority of railway line,and the seismic performance of the bridges need to studied intensively. To further study the simply-supported girder of high-speed railway in West China,a nonlinear numerical analysis model is established on the basis of the fiber unit to simulate the pier. With suitable simulation hypotheses of the fixed bearing dynamics performance,the nonlinear time history analysis is conducted to study the elastic-plastic seismic response and the damage mode under rare earthquakes. The calculation results show that the damage degree of bridge pier below 20 m height in transverse direction of bridge is heavier than that in longitudinal direction. In general,the pier has a better seismic performance. In view of the bearing failure under strong earthquake motion,reasonable control of relative displacements between superstructure and the pier should be addressed in seismic design of simply-supported girder of high-speed railway.