中文摘要：

研究了车桥耦合系统受轨道高低不平顺激励而产生的垂向非平稳随机振动。车辆采用具有两系悬挂10个自由度的四轮模型，桥梁采用Bernoulli—Euler梁单元有限元模型。系统激励源为轨道高低不平顺，假设其为均匀调制演变随机过程，并考虑车轮承受轨道激励相位差，采用虚拟激励法（PEM）将其精确地转化为一系列虚拟垂向简谐不平度的叠加，大大简化了运动方程的求解。同时采用精细积分法（PIM）的简单分解格式来进行数值积分计算，更真实地模拟了车辆与桥梁作用力在时间域和空间域上连续变化。最后通过两个算例给出了耦合系统响应统计值变化的时程曲线，分析了车辆运行速度和轨道不平顺对于系统随机响应的影响。数值计算表明：发展的虚拟激励一精细积分法能够高效精确地进行车桥耦合垂向系统的非平稳随机振动分析；车辆运行速度和轨道不平顺对系统随机振动都有较大影响。

英文摘要：

Vertical non-stationary random vibration of vehicle-bridge coupled systems subjected to track irregularity excitations is investigated. The vehicle is simulated by a four-wheel mass-spring-damper system with two layers of suspension systems possessing 10 degrees of freedom. The bridge is modeled as an elastic Bernoulli-Euler beam, and the track irregularity is assumed to be a uniformly modulated evolutionary random process with the phase-lags between the excitation of the track considered. Pseudo-excitation method （PEM is applied to transform the random surface roughness into the superposition of a series of deterministic pseudo harmonic surface unevenness and thus simplifies the solution of the nonstationary random vibration equations considerably. Meanwhile the precise integration method （PIM） is developed to simulate the continuous varying of the vehicle loads both in the time and space domains in the numerical integration process. The RMS curses given by numerical examples illustrate that the proposed method shows satisfactory efficiency and accuray, and the vehicle speed and track irregularity both have remarkable influences on the system random responses.