以三跨简支梁为例,进行车桥系统空间非平稳随机分析.将系统在确定性荷载作用下得到的响应作为均值,采用虚拟激励法将轨道高低、方向和左右轨高差不平顺转化为一系列简谐荷载,将系统在虚拟荷载作用下的响应的自功率谱密度积分得到均方差,运用3σ准则确定系统响应的最大、最小值,取其绝对值的较大值做为响应的代表值,讨论系统响应在不同车速下的变化趋势.研究表明:车体加速度、桥梁跨中横向响应和轮对受到横向轮轨力的随机性较大,轨道不平顺是其主要影响因素,桥梁跨中垂向响应及垂向轮轨力主要由确定性荷载引起.桥梁响应并不随车速的增加而单调增加,车体响应以及轮轨力随车速的增加而单调增加.%Spatial non-stationary stochastic response of train-bridge coupling system was analyzed, taking a three-span simply supported girder bridge as example. The response calculated when the coupling system is only under the determinable load was looked as the simulated mean value of response. Pseudo-excitation method (PEM) was applied to transform the track irregularities into the superposition of a series of deterministic pseudo harmonic surface unevenness. Auto-spectral density of the response was integrated to find the mean-square deviation. Maximum and minimum values of the response were obtained based on 3 principle. Larger value between the absolue values of the maximum and minimum was taken as the representative value of the response. Varying trend of the response was discussed under different speeds. The results show that the acceleration of car body, lateral response at bridge midspan and lateral wheel/rail force are of strong randomness and track irregularities are the major influential factor. Vertical response at bridge midspan and vertical wheel/rail force were caused mainly by the determinable load. Response of the bridge does not increase with the increase of train velocity, but response of car body and wheel/rail force do increase montonely.
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