基于小波变换的台风激励下千米级斜拉桥模态参数识别

Modal parameter identification of kilometer cable-stayed bridge under typhoon excitation based on wavelet transform

为了给大跨桥梁结构损伤识别和安全性评价提供现实依据,采用小波变换(WT)方法进行千米级斜拉桥的模态参数识别研究.以"海葵"台风激励下的苏通大桥为研究对象,基于结构健康监测系统(SHMS)采集的数据,采用WT方法共识别出包括频率和阻尼比在内的主梁前4阶竖弯模态参数、前2阶扭转模态参数和第1阶侧弯模态参数,并将结果与相关文献提供的模态参数进行对比;在此基础上研究了海葵台风期间该桥主梁模态参数的全过程变化情况.结果表明:基于WT的模态参数识别方法稳定可靠;随着时间的变化,主梁各阶模态频率均较稳定,而模态阻尼比的波动则较明显.

In order to provide realistic basis for structural damage identification and security evaluation of long span bridges, the modal parameter identification of a kilometer cable-stayed bridge was studied by using the wavelet transform （WT） method. The Sutong Bridge excited by the typhoon Halkui was taken as the research object. Based on the structural vibration responses recorded by the structural health monitoring system （SHMS） of this bridge, the first four vertical, the first two torsional and the first lateral modal parameters, including the frequency and the damping ratio of the girder, were identified by using the WT method. Then, these results were compared with those from some related references. On this basis, the whole process variation of the parameters of the girder during the typhoon Halkui was investigated. The results show that the modal parameter identification based on the WT method is stable and reliable. With the time passing by, the modal frequencies of the girder are stable while the modal ratios fluctuate obviously.