地震作用下结构拟静力分量对车桥系统动力响应的影响分析

Influence of structure quasi-static components on the dynamic response of train-bridge systems during earthquakes

在地震易发区域当地震发生时桥上正行驶列车的概率越来越大,然而地震作用下结构拟静力分量对于车桥系统动力响应影响的研究不足。将桥梁、车辆分别简化为等截面简支梁、簧上质量系统,建立耦合振动系统在多点地震作用下运动方程,将桥梁结构动力响应分解,推导出拟静力分量影响的精确表达式。在此基础上,给出耦合振动系统求解流程。以簧上质量系统通过32 m简支梁遭遇地震作用为例,进行结构拟静力分量影响规律研究。分析结果表明:1地震作用下车桥耦合振动分析考虑结构拟静力分量的影响需要输入地震位移、速度、加速度时程;2相对于桥梁子系统,结构拟静力分量对簧上质量系统影响较大,最大到16%,且该影响对于车速更加敏感;3忽略结构拟静力分量可能造成车桥动力分析结果出现较大偏差,这与结构抗震分析显著不同。

In regions prone to earthquakes,the possibility of trains running on bridges when an earthquake occurs is high.However,the influence of structure quasi-static components on the seismic response of train-bridge systems has not been well studied.In this paper,a bridge subsystem and the train subsystem were simplified as a simply-supported beam with a uniform cross-section and a moving vehicle with a wheel （unsprung-mass）,a spring,a damper,and a sprung-mass,respectively.Then the motion equations of the train-bridge coupling system subjected to multi-support seismic excitations could be obtained.The influence of structure quasi-static components could be expressed precisely by decomposing the dynamic response of the bridge subsystem and then the solving procedures were proposed.A moving vehicle with a wheel（unsprung-mass）,a spring,a damper and a sprung-mass passing through a 32 m simply-supported beam was taken as a case study,in which the influence rule of structure quasi-static components was analyzed.The results show：（1 ）in the dynamic analysis of the train-bridge system subjected to earthquake actions considering the influence of quasi-static components,it is necessary to input the displacement,velocity as well as acceleration time history of ground motion;（2）compared with the bridge subsystem,quasi-static components have more influence on the train subsystem, which is as high as 1 6% and sensitive to the train speed;（3）neglecting the quasi-static components may lead to large deviation responses of the coupled system,which differs greatly from the aseismatic analysis of bridges.