基于改进HHT的高拱坝模态参数识别方法研究  

Study on modal parameters identification method of high arch dam based on improved Hilbert-Huang transform

作　　者：李成业[1] 刘昉[1] 马斌[1] 宋明富 

机构地区：[1]天津大学水利工程仿真与安全国家重点实验室,天津300072 [2]二滩水力发电厂,四川攀枝花617000

出　　处：《水力发电学报》2012年第1期48-55,共8页Journal of Hydroelectric Engineering

基　　金：国家自然科学基金创新研究群体科学基金(51021004);国家杰出青年基金(50725929);西部交通建设科技项目(2009328000084)

摘　　要：水工结构出现损伤会使结构特定部分的质量或刚度发生损失,进而改变结构动力特性,这些都将在结构的模态信息中有所反映,因此如何精确地获取结构的模态信息是水工结构运行状态监测的重要前提。本文针对原型动力试验激励难的问题,结合水工结构环境激励荷载的特点,研究基于改进HHT(Hilbert-Huang Transform)的高拱坝模态参数方法。针对密频结构响应信号EMD分解过程中出现的模态混叠现象,提出了带通滤波和伪信号处理技术相结合的方法,对泄洪振动信号的EMD过程进行控制,得到结构的各阶模态分量,然后应用随机减量法提取出各阶模态分量的自由衰减信息,最后对自由衰减信息进行Hilbert变换和最小二乘拟合,得到拱坝的模态参数。Hydraulic structural damage will make mass or stiffness lose in certain specific parts of the structure,and then variate its dynamic behaviors,which is often reflected in modal information,and thus an accurate technique to obtain modal parameters is a key prerequisite of monitoring the structure operation conditions.Aiming at the difficulties in applying excitation in prototype test,this paper presents a method that directly identifies these modal parameters,with consideration of the features of ambient excitation and the dynamic response of structure under such an excitation.A combination method of band-pass filter and a spurious signal processing are put forward for the first time to solve the mode mixing problem in the EMD process of closely spaced signal of structure response.By this method,the EMD process of vibration signal is controlled and the accurate modal components of each mode are obtained.Then the free decay information is extracted from each modal component with the random decrement technique.In the last step,the structure modal parameters are obtained through a computation of Hilbert transform and least square fitting.

关 键 词：水工结构 模态参数 模态混叠 高拱坝 带通滤波 伪信号 

分 类 号：TV642.4[水利工程—水利水电工程]