车辆冲击荷载作用下桥梁振动响应分析

Analysis of bridge vibration response under vehicle impact load

如何测试行车荷载条件下桥梁的力学性能是桥梁动态测试的重要研究方向之一,考虑到路面平整度对桥梁动态测试影响的复杂性,提出采用枕木跳车测试技术来压制路面平整度影响的测试方法。首先,基于车-桥耦合振动理论,利用数值计算方法求解振动方程,研究了车辆行驶速度和路面平整度与桥梁冲击系数的关系。其次,建立了枕木跳车条件下车-桥振动系统模型,研究了车辆行驶速度、跳车高度、路面平整度对桥梁冲击系数的影响。研究结果表明:桥梁冲击系数在同一等级路面上满足正态分布,其在不同等级路面上变化显著;当车辆行驶速度、跳车高度满足一定条件时,路面平整度的影响可以忽略;经工程实例验证,该模型能准确反映简支梁在车辆冲击荷载作用下的响应,可以用于计算桥梁冲击系数。

Test on the mechanical properties of bridges under the moving loads of vehicles is one of the important aspects of bridge dynamic test.Considering the complex influence of the pavement roughness on the bridge dynamic test,this paper proposes a measuring technique of the crosstie vehicle′s bumping test which is aimed to suppress the pavement roughness.Firstly,based on the vehicle-bridge coupled vibration theory,the vibration equation is solved by numerical calculation method.The paper studies the factors that have significant influence on the bridge′s impact coefficient,such as the vehicle velocity and pavement roughness.Secondly,a vehicle bridge vibration system model under the condition of crosstie vehicle′s bumping is established.The calculation result shows the major factors which influence the bridge′s impact coefficient are vehicle speed and the height of vehicle′s bumping and pavement roughness.Analysis shows that the bridge′s impact coefficient follows Gaussian distribution on the same grade pavement,bringing significant changes on different grade pavements;the pavement roughness can be ignored when the vehicle speed and the height of vehicle′s bumping meet a certain condition.An engineering example shows that this model can accurately reflect the response of the simply supported beam under the impact load of the vehicle,and can be used to calculate the bridge′s impact coefficient.