对车桥耦合系统动力响应进行时频特性分析.以欧拉梁模拟有损伤的桥梁,以两轴汽车模型模拟移动车辆,利用有限元法建立有损伤桥梁结构在车辆作用下的运动方程.运用Newmark直接积分法计算出车桥耦合系统振动响应,分析不同裂缝模型对桥梁动力响应影响,并借助Hilbert-Huang变换获得损伤桥梁动力响应时频谱及边际谱.结果表明,由于呼吸裂缝影响,桥梁动力响应呈现明显的谐波效应；对比不同车流状况下桥梁动力响应时频特性,车流会对桥梁呼吸裂缝开合变化产生影响,随车辆的增多,桥梁振动加剧,谐波能量增大.%Here,the time-frequency analysis of a coupled bridge-vehicle system was performed.The bridge was modeled as an Euler beam with breathing cracks.A two-axle car model was used to represent a vehicle.A coupled bridgevehicle system was established using the finite element method,and Newmark direct integration was adopted to calculate the dynamic responses of the coupled system.The effects of different crack models on the dynamic response of the bridge were investigated.The HHT spectrum and HHT marginal spectrum of the dynamic response were obtained with HilbertHuang transformation (HHT).The results of the time-frequency analysis indicated that the complicated harmonic effects of the breathing cracks on the dynamic response of the system appear; the time-frequency characteristics of the responses with different traffic flows are also compared; the traffic flows have an effect on breathing cracks; the vibration of the bridge becomes larger and the energy of harmonics increases when more and more vehicles move passing the bridge.
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