Seismic Damage Assessment Based on Wavelet Packet Transform and Time-Varying Frequencies
HE Hao-xiang1,2, CHEN Kui1, YAN Wei-ming1,2
1．Beijing Key Lab of Earthquake Engineering and Structural Retrofit，Beijing University of Technology, Beijing, 100124，China;
2．Beijing Collaborative Innovation Center for Metropolitan Transportation，Beijing 100124，China
The seismic damage assessment method based on frequency changes is applied with the advantages such as clear mechanism and high precision, but the time resolution and the frequency resolution can not be accurately meet at the same time when the traditional methods for signal analysis are used. Hence, the time-varying frequencies cannot be obtained directly from the response signals and the application of this damage assessment method is insufficient. The corresponding accuracy evaluation criterion for different signal analysis methods is presented based on the marginal condition in time-frequency domain, and wavelet packet decomposition method with special wavelet basis functions is verified as an efficient tool in establishing time-varying power spectrum on the basis of theoretical and computational analysis. The time-varying frequency extraction method based on wavelet packet ridge is proposed, and the time-varying seismic damage index can be calculated according to frequency changes, furthermore, the multi-dimensional seismic damage assessment can be realized. The examples show that the damage assessment method based on wavelet packet transform and time-varying frequency can accurately reveal the overall damage evolution process and the eventual damage state. This method only requires structural displacement histories, and has superior adaptability on structural dynamic analysis, seismic design verification and seismic damage assessment for actual structures.
何浩祥1,2，陈奎1，闫维明1,2. 基于小波包变换和时变频率的结构地震损伤评估[J]. 振动与冲击, 2016, 35(7): 23-30.
HE Hao-xiang1,2, CHEN Kui1, YAN Wei-ming1,2 . Seismic Damage Assessment Based on Wavelet Packet Transform and Time-Varying Frequencies. JOURNAL OF VIBRATION AND SHOCK, 2016, 35(7): 23-30.
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