基于二轴车过桥振动响应的桥梁模态特性识别方法研究

Identification method of bridge modal characteristics based on vibration response of 2-axle vehicle passing through bridge

为采用移动车辆过桥振动信号间接识别桥梁模态特性参数,达到快速检测路网桥梁群健康状况目的,研究了常规二轴车用于桥梁频率与模态振型同步识别方法。首先,理论推导了忽略车桥耦合效应情况下二轴车过桥的车桥接触点振动响应封闭解,通过前后车轴振动加速度响应的时滞信号相减构建接触点残余响应,应用双峰理想谱滤波和希尔伯特变换建立了同步识别桥梁频率与模态振型方法。其次,建立了车桥耦合振动数值有限元仿真程序,在考虑车桥耦合效应基础上验证了理论推导的准确性,并同步识别了桥梁频率与模态振型。最后,考虑更不利的路面粗糙度情况,检验了二轴车接触点残差响应的间接识别效果。研究表明在忽略车桥耦合效应情况下接触点残差响应不包含车辆和路面粗糙度影响,可以精准识别桥梁模态特性参数。数值有限元仿真证明通过车体响应间接计算接触点响应、通过桥梁节点插值计算接触点响应以及理论推导三者结果高度吻合,在路面粗糙度等级低的情况下该方法有很好效果。当粗糙度更为不利时,车桥耦合效应明显导致接触点响应残差中仍然包含车辆频率成分,对识别效果有一定干扰。采用接触点残余响应进行桥梁模态特性识别时,建议降低检测速度或优化试验车构造,抑制车桥耦合效应的不利影响。

Here,to indirectly identify modal characteristic parameters of bridge using vibration signals of mobile vehicles passing through bridge and achieve the goal of quickly detecting health status of road network bridge groups,the conventional 2-axle vehicle method for synchronous identification of bridge modal frequencies and modal shapes was studied.Firstly,closed form solutions for vibration responses of vehicle-bridge contact points of 2-axle vehicle passing through bridge were theoretically derived ignoring vehicle-bridge coupled effect.Residual response of contact points was constructed by subtracting time-delay signals of vibration acceleration responses of front and rear axles.The synchronous identification method for bridge modal frequencies and modal shapes was established with dual-peak ideal spectrum filtering and Hilbert transform.Secondly,the finite element numerical simulation program for vehicle-bridge coupled vibration was established to verify the correctness of theoretical derivation considering vehicle-bridge coupled effect,and synchronously identify bridge modal frequencies and modal shapes.Finally,considering more unfavorable road roughness situation,the indirect recognition effect of residual response of contact points of 2-axle vehicle was detected.The study showed that if ignoring vehicle-bridge coupled effect,residual response of contact points does not include effects of vehicle and road roughness,it can accurately identify modal characteristic parameters of bridge;using finite element numerical simulation,contact point response results indirectly calculated with vehicle body response,contact point response results calculated with bridge node interpolation and contact point response results obtained using theoretical derivation are highly consistent,this method has a good effect in the case of low road roughness level;when the road roughness is more unfavorable,the vehicle-bridge coupled effect obviously causes residual response of contact points still containing vehicle frequency components to have a certain interference to recognition effect;when using residual response of contact points for bridge modal characteristics identification,it is recommended to reduce detection speed or optimize test vehicle structure for suppressing unfavorable influences of vehicle-bridge coupled effect.