拟静力分量对列车-轨道-桥梁系统地震响应的影响

为探讨结构拟静力分量对地震作用下高速铁路桥上列车行车安全性的影响,考虑路基和桥梁地震力边界条件,分别采用相对运动法和大质量法,在相对坐标系和绝对坐标系下处理地震力边界条件,建立了不同坐标系下的列车-轨道-桥梁系统地震响应分析模型.以跨度48 m+580 m+48 m的刚构-连续组合梁桥为例,分析了结构单向和三向拟静力分量对列车-轨道-桥梁系统地震响应的影响.结果表明:结构横向拟静力分量将显著增大桥梁横向位移、钢轨横向位移、列车脱轨系数和轮重减载率,而纵向、竖向拟静力分量的影响甚微;同时考虑结构的三向拟静力分量时,列车脱轨系数和轮重减载率均显著增大,且其相对误差随列车速度提高而增大,最大达30.5%和22.2%.因此,不考虑结构拟静力分量在列车速度较高时将严重低估车辆的动力响应,对桥上列车的行车安全性造成误判. 

Effects of Structural Quasi-static Components on Seismic Responses of Train-Track-Bridge System

In order to discuss the effects of structural quasi-static components on the running safety of a train running over a high-speed railway bridge subjected to earthquake action, two dynamic models for a train-track-bridge system subjected to seismic excitation were set up by considering the seismic force boundaries of subgrade and bridge in relative coordinates and absolute coordinates, and the seismic force boundaries were processed respectively by the relative movement method and the large mass method. A rigid-continuous combination beam bridge with spans of 48 m+580 m+48 m was taken as an example, and the effects of structural quasi-static components in different directions on the seismic responses of the train-track-bridge system were analyzed. The research results show that the transversal quasi-static component causes a significant increase in dynamic responses, including the transversal displacements of bridge and rail, derailment coefficient and wheel unloading rate. The longitudinal and vertical quasi-static components have little effect on the seismic responses of the coupling system. When the quasi-static components of all three directions are considered, the derailment coefficient and wheel unloading rate of train increase significantly, their relative errors increase with the raising of train speed and the maximum relative errors can reach 30.5% and 22.2%, respectively. So, if the effects of structural quasi-static components are ignored to a train running through a bridge under earthquake action at a high speed, the dynamic responses of vehicle will be substantially undervalued to lead to an incorrect judgment of the running safety.