基于改进Hilbert-Huang变换的结构损伤识别方法研究

Structural damage detection based on improved Hilbert-Huang transform

针对Hilbert-Huang变换(HHT)在信号处理中存在的模态混叠的问题,引入总体经验模态分解(EEMD)对HHT方法进行改进,并将改进的HHT方法应用于工程结构损伤识别中。建立一个三自由度剪切型结构模型,结构刚度退化模型采用双线性刚度退化模型,计算结构在地震作用下的响应,对结构加速度响应进行改进的HHT分析,提出了利用损伤前后结构响应一阶固有模态函数(IMF)特征能量比识别结构损伤位置的方法。结果表明:通过结构响应瞬时频率的变化可以判断结构是否损伤和出现损伤的时间,根据损伤前后各层一阶IMF能量比的变化可以识别损伤的位置。将改进的HHT应用到对实际工程的强震记录分析中,通过提取一阶瞬时频率和一阶IMF特征能量比较好地识别了结构在强震作用下的损伤。

Aiming at the problem of mode mixing in signal analysis by using Hilbert-Huang transform （HHT）, an improved HHT method based on ensemble empirical mode decomposition （EEMD）was introduced and applied in the identification of structural damages. A three degrees of freedom bilinear stiffness degradation model of shear type structure was established. Structural responses under earthquake were calculated and analyzed by the improved HHT. A method to detect the location of damage based on intrinsic mode function （IMF） energy was proposed. It is shown that whether or not a structure is damaged and when the damage occurs can be decided by an instantaneous frequency change of structural acceleration and the location of damage is detected by the variation of corresponding IMF energy at the first modal frequency of structural response before and well identified by extracting the first modal after damage. The damage of an actual engineering under earthquake can be instantaneous frequency and the first modal IMF energy.