车桥耦合振动的桥面非平稳随机激励模拟

Simulation of Non-stationary Random Excitation of Bridge Deck under Vehicle-bridge Coupling Vibration

为研究桥面非平稳随机激励对车桥耦合系统的影响,采用滤波白噪声法生成单轮桥面非平稳随机激励时域模型,结合车辆前后轮的时间滞后和左右轮的相干关系,生成车辆六轮相关的桥面非平稳随机激励样本并验证了样本的有效性。分析一座3×30 m连续T梁桥和一辆三轴重载汽车在非平稳桥面激励下的车桥耦合振动响应,现场实测桥面不平度,并采用传统蒙特卡罗法对车辆和桥梁的振动响应进行计算。研究结果表明:根据车辆六轮间的时间滞后关系和相干函数关系所建立的桥面非平稳随机激励模型满足目标相干函数和功率谱密度,且时间滞后关系明确,模型有效可靠;当车辆加速行驶时,因桥面不平顺引起的非平稳随机激励信号的幅值随速度的增大而增大,非平稳激励下的桥梁和车辆振动响应大于平稳激励所产生的振动响应;非平稳激励对桥梁振动响应的均值影响很小,但对车辆振动响应均值影响较大,车辆振动对桥面随机激励更敏感;非平稳激励对车辆和桥梁振动响应标准差的影响较大,且振动响应标准差随着车辆加速度的提高而增大;研究车桥耦合振动很有必要考虑车辆非匀速行驶而引起的桥面非平稳随机激励,建议车辆匀速通过桥梁,尽量避免在桥上加速行驶。

In order to study the influence of non-stationary random excitation of vehicle-bridge coupling system,a time-domain model of single wheel non-stationary random excitation of bridge deck is generated by using the white noise filtering method.Combining the time lag of vehicle front and rear wheels and the coherence between left and right wheels,a sample of 6-wheel correlated non-stationary random excitation of bridge deck is generated and the validity of the sample is verified.The coupling vibration response of a 3×30 m continuous T-beam bridge and a 3-axle heavy-duty vehicle under the non-stationary excitation of bridge deck is analyzed.The bridge deck unevenness is measured on site,and the vibration response of vehicle and bridge is calculated by traditional Monte Carlo method.The result shows that(1)the non-stationary random excitation model based on the time lag relationship and the coherence function relationship between 6 wheels of the vehicle satisfies the objective coherence function and power spectral density,the time lag relationship is clear,and the model is effective and reliable;(2)when the vehicle accelerates,the amplitude of the non-stationary random excitation signal caused by the deck irregularity increases with the increase of the speed,and the vibration response of bridge and vehicle under non-stationary excitation is larger than that under stationary excitation;(3)non-stationary excitation has little influence on the mean value of bridge vibration response,but it has a greater influence on the mean value of vehicle vibration response,vehicle vibration is more sensitive to random excitation of bridge deck;(4)non-stationary excitation has great influence on the standard deviation of vehicle and bridge vibration response,and the standard deviation of vibration response increases with the increase of vehicle acceleration.It is necessary to consider the non-stationary random excitation of bridge deck caused by vehicle non-uniform driving in the study of vehicle-bridge coupling vibration.It is suggested that vehicles should pass through bridge at uniform speed and avoid accelerating driving on bridge as much as possible.