基于桥梁单元刚度损伤识别的新型间接量测方法研究

Bridge Element Bending Stiffness Damage Identification Based on New Indirect Measurement Method

基于移动车辆在桥梁上运行来测试桥梁基频的间接量测法已经获得实桥的验证,提出一种新型间接量测法,该方法有别于牵引车拖动测试车辆一直运行并同步采集信号的传统间接量测方式,需牵引车同时拖动固定间距的前、后2辆测试车辆前行,并在固定点静止采集少许时间后,继续重复操作至测试车辆通行整跨桥梁,利用测试车辆上采集的信号,计算整跨桥梁的传递率矩阵,然后利用奇异值分解识别出桥梁的第1阶模态,进而利用改进的直接刚度法计算桥梁单元弯曲刚度,并进行损伤识别。首先从理论上说明该方法的可行性,然后在各类影响因素下进行数值模拟分析,最后通过某实桥试验进行初步验证。研究结果表明:相比于常规在桥梁上直接测试的方法,提出方法耗时短,机动性好,适用于大面积大区域桥梁集群快速测试;相比于传统间接量测方式,提出方法通行时间虽有少量增加,但能较好解决桥梁阻尼比、测试车阻尼、外激励变化、噪音、桥面粗糙度等传统间接量测方法中存在的问题。

An indirect measurement method to test the fundamental frequency of a bridge based on a moving vehicle running on the bridge has been verified in a field test.The new indirect measurement method is different from the traditional indirect measurement method,where a tractor drags the test vehicle and collects signals synchronously.In this study,the tractor is required to move forward while simultaneously dragging two test vehicles at a fixed distance.Signals are collected for a short period of time as the test vehicles move to each designated measuring point,repeating the operation until the two test vehicles pass through the entire span of the bridge.The transfer rate matrix of the entire span of the bridge is calculated,and then the singular value decomposition is used to identify the first-order mode shape of the bridge.Then,the element bending stiffness of the bridge can be evaluated by using the improved direct stiffness method for damage identification.First,the feasibility of the method is illustrated theoretically,and then the numerical simulation analysis is performed by considering various influencing factors.Finally,a field test is carried out on a practical bridge.The results show that the element bending stiffness of the bridge can be obtained by using the new indirect measurement method.Compared with the direct test method on the bridge,the new method is quicker,less work,and good mobility.It is suitable for the rapid testing of large-area bridge clusters.Compared with the traditional indirect measurement method,although the new method has a small increase in data collection time,it can better address the problems of the bridge damping ratio,test vehicle damping,external excitation variation,environmental noise,and other factors.