运用小波分析方法进行结构模态参数识别

结构的模态参数反映了结构自身特性，是基于动态特性的结构损伤识别和健康评估的重要因子。本文首先介绍了环境激励下基于小波分析的模态参数识别方法，针对土木工程结构的前几阶自振频率处于低频区域以及环境激励下结构响应信号信噪比很低的特点，着重论述了采用小波方法抑制原始测量信号中的高频成分（即噪音），从而突出结构低频特性的降噪处理方法的基本原理。通过比较传统傅里叶变换、短时傅里叶变换和小波变换三种方法对一实际高层建筑结构现场测试信号的处理结果以及有限元分析结果，认为小波分析方法可以更精确、更有效地识别工程结构的模态参数。

IDENTIFICATION OF STRUCTURAL MODAL PARAMETERS WITH WAVELET TRANSFORMATION

Structural modal parameters reflecting intrinsic characteristics of a structure are critical factors in vibration-based damage detection and health assessment. Firstly,application of wavelet analysis for important identification of structural modal parameters under environmental excitation is introduced.First several natural frequencies of civil engineering structures are mainly in low frequency region and signal-noise ratio of structural response signals under environmental excitation is usually lower,thus,emphasis has then been laid on the denoising technology based on wavelet analysis,which filters the curde signals and gains more worthy information by restraining high frequency components and extracting low frequency ones.The comparison between identified results of an actual tall building through field test by using traditional Fourier transformation(FT), short-time Fourier transformation(STFT) and Wavelet transformation(WT) and the theoretical results from its finite element model indicates that the wavelet-based method is able to extract its characteristics more accurately and more effectively.