车-轨-桥耦合系统中的非一致地震输入方法研究

Input methods of non-uniform seismic excitation in coupling system of vehicle-track-bridge

为分析地震输入方法对列车-轨道-桥梁系统地震响应的影响,考虑路基和桥梁地震力边界条件,分别采用直接求解法、相对运动法、大质量法和大刚度法输入非一致地震激励,建立不同地震输入方法下的列车—轨道—桥梁动力分析模型,以跨度(48+5×80+48)m的刚构-连续组合梁桥为例,对比不同地震输入方法下车桥系统的地震响应。结果表明:大刚度法与直接求解法求得的车桥地震响应完全相同;大质量法求得的脱轨系数和轮重减载率相比直接求解法偏大,最大偏差达44.0%和26.4%;相对运动法求得的脱轨系数、轮重减载率和桥梁位移相比直接求解法偏小,最大偏差分别为32.5%,12.8%和51.9%。由于大刚度法只需输入地震动位移时程,相比直接求解法计算更为简便,因此,在列车-轨道-桥梁耦合系统中大刚度法是输入非一致地震激励的最优方法。

In order to analyze the influence of input method of seismic on the seismic responses of train -track -bridge system,a dynamic model of train -track -bridge system subjected to earthquakes through considering the seismic force boundary of subgrade and bridge was set up.Four input methods of seismic,including direct sol-ving method,relative movement method,large mass method and large stiffness method,were presented and de-duced.As an example,a rigid -continuous combination beam bridge with spans of 48 ＋5 ＆#215;80 ＋48m was mod-eled,and the seismic responses of vehicle and bridge system under San Fernando seismic wave were calculated and compared.The results show that the seismic responses of vehicle and bridge system solved by large stiffness method and direct solving method are the same.The derailment coefficient and wheel unloading rate solved by large mass method are larger than the ones solved by direct solving method and the maximum deviation are 44.0% and 26.4%,respectively;The derailment coefficient,wheel unloading rate and displacement of bridge solved by relative movement method are smaller than the ones solved by direct solving method and the maximum deviation are 32.5%,12.8% and 51.9%,respectively.Because only the seismic displacement time history is needed for the large stiffness method and the computational process of the large stiffness method is more simple compared with the direct solving method,the most optimal method to input the non -uniform seismic excitations in dynamic system of train -track -bridge is the large stiffness method.