基于路面一致激励车桥耦合非平稳随机振动分析

Analysis of Consistent Stimulus of Road Roughness on Vehicle-Bridge Coupling Nonstationary Random Vibrations

基于路面不平顺一致输入激励,采用虚拟激励法研究车辆变速行驶三维车桥耦合非平稳随机振动响应。首先,将桥梁离散为板-壳实体单元,车辆简化为三维九自由度体系,考虑路面输入激励的多点不相干,将路面不平顺引起的荷载等效为虚拟激励荷载,建立三维车-桥耦合非平稳随机振动模型;然后,运用精细积分格式迭代求解,与Monte-Carlo法计算结果对比验证模型的正确性;最后,以某高速公路梁桥为背景,研究车辆匀加速行驶在B级桥面桥梁各点动响应。结果表明:笔者提出的计算模型及算法正确可行;相同路面激励引起的跨中位移和加速度响应峰值大小取决于瞬时最大车速;车辆变速行驶比匀速行驶具有更宽的共振频率区间,跨中位移和加速度最大值随车速呈现先快后缓的增长趋势。

The vibration responses of a 3D random model for a vehicle-bridge system subjected to running vehicle at nonconstant speed are resolved by pseudo excitation method(PEM)based on a consistent stimu lus of road roughness.Taking multipoint coherent road roughness excitation into condition,a new 3D random vibration model for vehicle-bridge systems is proposed.In the vehicle-bridge coupling model,the bridge is modeled as a beam-shell solid element,the vehicle is simplified as a 3D freedom model with nine degrees and the load caused by the road roughness is equivalent to a pseudo excitation load.The model is resolved by a precise integration method(PIM),and the accuracy of results is verified through comparing with the results of a Monte-Carlo method.Taking one highway beam bridge as an example,different point dynamic responses of the bridge subjected to uniformly accelerating vehicle have been researched.The results prove the accuracy and feasibility of the vehicle-bridge coupling random vibration model which has been proposed in the paper.The vehicle speed is the most fact which leads to a peak displacement and a peak acceleration at mid-span with the same road roughness excitation.There is more large resonance frequency region when the vehicle runs on bridge with a nonconstant speed than a constant one.The peak displacement and peak acceleration at mid-span of growth appears fast followed by slow when the vehicle speed increases gradually.