高速铁路门式墩-桥梁-轨道系统地震响应特征

Characteristics of seismic response of high-speed railway frame pier-bridge-track system

为研究地震作用下门式墩结构对梁轨系统受力特性的影响,以合福线高速铁路某门式墩上3跨32 m简支梁桥为例,采用经验证的梁轨接触模拟方法,建立门式墩-桥梁-轨道系统精细化动力仿真模型。研究在多维地震作用下门式墩上简支梁桥-轨道系统动力响应特征,探讨节点连接方式、横梁刚度等关键设计参数对系统受力特性的影响规律。研究结果表明:采用门式墩结构后,结构体系刚度相对较小,系统自振频率降低;在地震作用下,采用门式墩结构的简支梁桥上钢轨纵向应力包络线呈菱形分布,其应力峰值均发生于墩、台及桥梁跨中附近;与普通墩相比,门式墩立柱底最大纵向剪力明显增大,钢轨节点的横向位移减小;水平地震激励角对门式墩系统受力、变形影响较大,在分析过程中需要加以考虑;在竖向地震作用时,钢轨及门式墩墩顶的竖向挠曲随着门式墩梁柱节点刚度的增大略减小;鉴于刚性节点可能导致结构延性降低、残余应力增大等,建议门式墩梁柱节点采用半刚性连接。

In order to study the influence of portal pier structure on the force characteristics of the beam-track system under earthquake action,a refined dynamic simulation model of portal pier-bridge-track system was established by using a verified beam-track contact simulation method with a three simply supported beams with length of 32 m on a portal pier of the Hefei-Fuzhou High-speed Railway as an example.The dynamic response characteristics of simply supported beam bridge-track system on portal pier under multi-dimensional seismic action were investigated and the influence of key design parameters such as node connection method and beam stiffness on the system stress characteristics was discussed.The results show that the structural system stiffness is relatively flexible after using portal pier structure.The natural vibration frequency of the system is reduced.During the earthquake,the longitudinal stress envelope of rails on simply supported beam bridges with portal pier structures is rhombic in shape,with the peak stresses occurring near the piers,abutments and bridge spans.The vertical deflection of the rails and the top of the portal pier slightly decreases with the increase of the stiffness of the portal pier beam-column nodes.In view of the disadvantages of rigid nodes that may lead to reduced structural ductility and large residual stresses,it is suggested that beam-column joints of portal pier should adopt semi-rigid connection.