城市轨道交通“公轨合一”型高架桥车桥耦合振动分析

VEHICLE-BRIDGE INTERACTION ANALYSIS OF A SUPER BRIDGE IN URBAN RAILWAY SYSTEM

对某"公轨合一"型高架桥进行了汽车-列车-桥梁耦合振动分析。利用薄板单元和梁单元建立了桥梁的有限元模型,推导了17自由度可以考虑列车车体空间效应的整车垂向模型,引入轨道不平顺因素,轮轨关系假定为密贴,列车-桥梁耦合系统采用分离迭代法求解,利用ANSYS平台和自主编制的FORTRAN计算程序实现,汽车荷载采用移动常力模型,分析了不同工况下车桥子系统之间的影响,同时还讨论了轨道不平顺因素对该车桥耦合系统的影响。结果表明:该文所研究桥梁模型的上部公路部分和下部轨道部分各自通行车辆荷载时相互之间的影响很小,作者认为在做该桥梁的强度设计时,可以忽略上下部分的耦合影响;同时,对于该文模型,当列车车速为低速时(60 km/h),轨道不平顺因素对于桥梁跨中位移的影响很小,因而在做桥梁强度设计时,列车荷载可按轴荷取值而忽略轨道不平顺带来的动态效应。该结论可供同类桥梁设计时作为参考。

Vehicle-Metro-Bridge interaction analysis was conducted upon a super bridge in an urban railway system. The bridge consists of viaducts and railway lines. The numerical analysis in time domain based on the Finite Element Method was applied to the research. The FE model of the bridge was built by using a thin plate and a beam element. The analytical model of the metro has 17 degrees of freedom, of which the carriage is three-dimensional. The parameters of the metro model are determined based on the B type metro. One part of the loadings, vehicle loadings, was designed as a set of moving constant loadings in a range of situations. On the other, the Metro-Bridge interaction model was solved by using a separate iteration method, combining ANSYS and FORTRAN procedures. In this procedure, the wheel-rail interaction was assumed as a non-jump model and the track irregularity was took into consideration as well. Some analyses focused on the running smoothness of metro carriages under a set of situations, and the influence of the track irregularity upon the mid-span dynamic displacement was also discussed. The results states that viaduct and railway line interfere each other slightly. The track irregularity creates little impacts on the mid-span displacement of viaduct and railway line when metro＇s velocity is low. These two results can be a reference to the structural strength design of similar bridges.