基于车桥接触点响应的桥梁振型与损伤识别研究

Research on Mode Shapes and Damage Identification of Bridge Based on Vehicle-bridge Contact Point Response

以过桥车辆为桥梁动态特性的信息载体对桥梁进行监测,避免了利用动载试验测量桥梁模态参数而存在的成本高、操作复杂等缺陷。基于车辆与桥梁之间的耦合作用,结合中心差分方法得到车辆与桥梁的接触点加速度,利用变分模态分解与希尔伯特变换获得桥梁的各阶分量响应,并重构振型。以某一简支梁桥为例,研究车速、路面粗糙度、随机交通等参数对振型识别的影响,利用重构的一阶振型结合曲率模态法对桥梁的损伤定位进行了探索。结果表明:路面粗糙度对振型识别不利,通过加入一辆伴随车辆激励桥梁能较为精确地识别出A级粗糙度下桥梁的前三阶振型。由于随机交通的存在,量测车采集到的加速度信号中包含交通流中车辆的频率信息,但重构的振型仍可以满足工程精度。当量测车的行驶速度较低时,信号数据中包含的桥梁模态信息丰富,重构的一阶振型具有较高的分辨率,结合曲率模态法可以准确地定位桥梁的损伤。

Using vehicle as the information carrier of bridge dynamic characteristics to monitor the bridge avoids the defects of high cost and complex operation in measuring bridge modal parameters by dynamic load test.Based on the coupling effect between the vehicle and the bridge,the acceleration of the contact point between the vehicle and the bridge is obtained by combining the central difference method,and the response of each order component of the bridge is obtained by using the variational mode decomposition and the Hilbert transform,hence the mode shapes are reconstructed.Taking a simply supported beam bridge as an example,the influence of parameters such as vehicle speed,road surface roughness and random traffic on mode shapes identification are studied.The damage location of the bridge is explored by using reconstructed first-order mode shape combined with curvature mode method.The results show that the road surface roughness is unfavorable for the mode shapes identification.By adding a companion vehicle to excite the bridge,the first three mode shapes of the bridge can be more accurately identified under the A-level roughness.Due to the existence of random traffic,the acceleration signal collected by the measuring vehicle contains the frequency information of the vehicle in the traffic flow,but the reconstructed mode shapes can still meet the engineering accuracy.When the speed of the measuring vehicle is low,the bridge modal information contained in the signal data is rich,the reconstructed first-order mode shape has a high resolution,and the damage of the bridge can be accurately located with the curvature mode method.