基于车轮-桥面相干激励的大跨连续梁桥振动响应

Vibration response of continuous girder bridge based on wheel⁃deck coherent excitation

为获取桥面相干激励下大跨连续梁桥动力响应规律,基于虚功原理,建立五轴重载车辆动力学模型,采用模态叠加法建立桥梁动力方程,通过谐波叠加法建立桥面相干激励模型,根据轮-桥间几何和力学耦合关系,组建车轮-桥面相干激励模型,采用Matlab软件编译大跨连续梁桥车桥耦合振动分析系统,并开展不同等级的相干桥面激励模型对大跨连续梁桥动力响应影响研究。结果表明:当未考虑桥面不平顺影响时,桥梁冲击系数均小于规范取值,但随着桥面状况的恶化,结构典型截面的动力响应增长较快,且完全相干模型对桥梁动力响应的影响均大于部分相干激励模型,均超过规范值,其中挠度幅值最大偏差约为7.7%,弯矩幅值最大偏差约为20%,挠度冲击系数相对误差为4%~34%,弯矩冲击系数相对误差为2%~43%;随着车速的增大,桥梁冲击系数呈先增大后减小变化。最后,给出了大跨连续梁桥挠度和弯矩冲击系数包络图。相关研究成果可为连续梁桥的结构动力响应的分析与研究提供参考。

To obtain the dynamic response characteristics of long-span continuous beam bridges under coherent excitation of the bridge deck,a comprehensive analysis was conducted based on the principle of virtual work.Firstly,a dynamic model of a five-axle heavy-load vehicle was established.Then,the bridge's dynamic equation was derived using the modal superposition method,a wheel-deck coherent excitation model was established by considering the geometric and mechanical coupling between the wheels and the bridge.The coupled vibration analysis system of the long-span continuous beam bridge was implemented using Matlab software.Subsequently,the impact of different levels of coherent deck excitation models on the dynamic response of the bridge was investigated.The findings revealed that when the influence of bridge deck irregularity was ignored,the impact coefficients of the bridges were smaller than the standard values.However,as the condition of the bridge deck deteriorated,the dynamic response of the representative cross-section of the structure increased significantly.Moreover,it was observed that the completely coherent excitation model had a greater influence on the dynamic response of the bridges compared to the partially coherent excitation model,exceeding the standard values.The maximum deviation of the deflection amplitude was approximately 7.7%,with a maximum deviation of bending moment amplitude of around 20%.The relative errors in deflection impact coefficient ranged from 4%to 34%,while the relative errors in bending moment impact coefficient ranged from 2%to 43%.Additionally,it was noted that the impact coefficient of the bridge initially increased and then decreased with an increase in vehicle speed.Finally,an envelope diagram illustrating the deflection and moment impact coefficients of the long-span continuous beam bridge was provided.These research findings offer valuable insights for the analysis and study of the structural dynamics and response of continuous beam bridges.