基于车辆静置的桥梁模态参数识别方法

Parked vehicle based bridge modal identification method

针对传统工作模态参数识别中存在的振型难以质量归一化和传感器数量多,“移动车辆扫描法”存在对路面不平顺过于敏感和振型难以质量归一化等问题,提出一种采用少量传感器且对路面不平顺不敏感的桥梁模态参数(频率和质量归一化振型)识别方法。该方法将车辆停靠于选定位置,形成静置车辆-桥梁系统,测试系统频率;测完后移动车辆至下一位置,重新停靠后测试频率,以此类推,“随停随测,即测即走”,通过系列系统频率识别模态参数,因此称之为基于车辆静置的模态参数识别。首先,采用数值算例展示静置车辆-桥梁系统频率随着车辆静置位置的变化而变化的现象;其次,通过理论推导揭示静置车辆-桥梁系统频率演化与桥梁模态参数之间的物理关系;然后,提出通过测试系列静置车辆-桥梁系统频率来识别桥梁模态参数的流程并予以验证;最后,系统讨论车/桥质量比和车辆刚度等因素的影响。结果表明:提出的方法化振型识别为频率识别,只需少量加速度传感器,便能快速识别桥梁质量归一化振型。

The traditional operational modal identification involves a large number of sensors and is unable to obtain the mass-normalized mode shape,while the"Moving Vehicle Scanning Method"with limited sensors is usually too sensitive to the irregularity of road surface and difficult to mass-normalize the mode shape.A bridge modal identification method(for frequency and mass-normalized mode shape)that is insensitive to road surface irregularity by using a small number of sensors is proposed.In this method,the vehicle is parked on a selected position to form a parked vehicle-bridge system and the corresponding frequency is estimated.Then the vehicle is moved to the next position and the test procedure is repeated,and so on.The modal parameters are identified via measuring a series of parked vehicle-bridge systems,and thus it is named the"Parked Vehicle based Bridge Modal Identification Method".Firstly,numerical examples are used to demonstrate the phenomenon that the frequencies of the parked vehicle-bridge systems change with the position of the parked vehicle.Secondly,the physical relationship between the frequency variation of the parked vehicle-bridge system and the bridge modal parameters is revealed through theoretical derivation,and the modal identification theory is established accordingly.Then the modal identification procedures by measuring a series of frequencies of the parked vehicle-bridge systems is provided and verified.Finally,the influences of vehicle/bridge mass ratio and vehicle stiffness on the identification results are investigated systematically.The results indicate that the mode shape identification is transformed into frequency identification,and the mass-normalized mode shape of bridge can be quickly identified with only a small number of acceleration sensors.