The large-span simply-supported steel truss girder bridge on the mixed passenger and freight railway features long span,heavy live load,among others.In this paper,based on the case study of a 156 m large-span simply-supported steel truss girder bridge,a simulation model considering the nonlinear hysteretic characteristics of the adjacent bridges,the subgrade,the beam and the track was established for the simply supported steel truss girder bridge with large span.The seismic response of interaction between large-span simply-supported steel truss girder bridge and CWR (continuously welded rail) due to longitudinal seismic traveling wave effect and vertical seismic excitation was analyzed.The influence of temperature change before earthquake on seismic response of railway track-bridge system was explored.In the model,the roadbed and hysteretic effect in the longitudinal resistance of CWR was considered.Calculation results showed that seismic travelling wave effect,which caused the truss axial force of steel truss girder,relative beam end displacement and rail stress to increase significantly,would adversely affect the seismic response of the large-span simply-supported steel truss girder bridge and the CWR on it.The existence of the track structure further increased the axial force response of the steel truss girder.The truss axial force response was extremely sensitive to the apparent wave velocity.With the increase of apparent wave velocity,the rail stress decreased and tended to respond under the uniform excitation.The significant impact of temperature change before earthquake on track stress should be considered.For the bridge in the article,the maximum axial force of the truss under vertical seismic excitation was 1.5 times (tension) and 0.8 times (pressure) greater than the axial force under longitudinal seismic excitation.The maximum value of the rail stress in the steel truss girder was reduced by 42%.%客货共线铁路大跨简支钢桁梁桥具有跨度大、活载重等特点,本文以156 m简支钢桁梁桥为例,建立考虑相邻桥梁、路基和梁轨间非线性滞回特性的大跨简支钢桁梁桥-轨道系统仿真模型,分析纵向行波效应和竖向地震作用下大跨简支钢桁梁桥-轨道系统动力响应特征,探讨震前温度变化对系统地震响应的影响规律.研究表明:行波效应使钢桁梁桁架轴力、梁端相对位移及钢轨应力显著增大,对大跨简支钢桁梁桥和桥上无缝线路的抗震均有不利影响,轨道结构的存在进一步增大钢桁梁桁架轴力响应;桁架轴力响应对视波速极为敏感;钢轨应力随视波速增大而逐渐减小,并趋于一致激励下响应;震前温度变化对轨道应力影响显著,应予以考虑;对本桥而言,与顺桥向激励相比,竖向激励下桁架最大轴力增大1.5倍(拉)和0.8倍(压),钢桁梁段钢轨应力最大值减小42%.
展开▼
