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基于工程结构振动信号的分析与处理识别结构的模态参数,是结构健康监测和损伤诊断的重要手段之一。基于傅里叶分析的信号处理方法对非线性、非稳态信号的处理能力差,传统的模态参数识别方法也存在阻尼比识别精度不高的问题。基于Hilbert-Huang变换和自然激励技术,提出了一种新的模态参数识别方法,首先通过经验模态分解和Hilbert变换提取信号的瞬时特性,进而利用自然激励技术和模态分析的基本理论识别结构的模态频率和模态阻尼比。利用这一方法,对12层钢筋混凝土框架模型振动台试验一测点的加速度记录进行了处理,识别了模态参数,识别结果与其它识别方法及有限元分析结果的对比表明该方法识别模态频率是可靠的,而模态阻尼比的识别虽然较传统的基于傅里叶变换的半功率带宽法有所改进,但识别的精准性仍然难以确认。
Analysis and processing of structural vibration signals to identify modal parameters of the structure are one of the important means of structural health monitoring and damage diagnosis. The signal processing method based on Fourier analysis has poor ability to process nonlinear and unsteady signals, and the traditional method of modal parameter identification also has the problem of low accuracy of damping ratio identification. Based on the Hilbert-Huang transform and the natural excitation technique, a new method of modal parameter identification is proposed. First, the transient characteristics of the signal are extracted by empirical mode decomposition and Hilbert transform, and then the natural excitation technique and the basic theory of modal analysis are used to identify Modal frequency and mode damping ratio of the structure. Using this method, the acceleration records of a measuring point in shaker test of 12-story reinforced concrete frame model were processed and the modal parameters were identified. The comparison between recognition results and other identification methods and finite element analysis results showed that this method could recognize modal The frequency is reliable, while the recognition of modal damping ratio is improved compared with the traditional half-power bandwidth method based on Fourier transform, but the recognition accuracy is still hard to confirm.