The Application Study Of Wavelet Transform And Hilbert-Huang Transform (HHT) In Structural Aseismatic Engineering

Structural earthquake records are the signals that contain a lot of structural response information and motion information. They are basic data to investigate earthquake engineering and the design of aseismatic engineering. In order to gain important information of earthquake records and its characteristics, Fourier transform is used traditionally. With the development of information technology, all kinds of signal management technologies come into being and flourish in recent 20 years, such as Wavelet transform, Hilbert-Huang transform (HHT for short). This paper investigates the last two new methods and their characteristics in order to find their foreground in earthquake records management and analysis, and to discuss possible influence in earthquake function in combination with Fourier transform. At the same time, the shortcoming of aseismatic response spectrum is discussed, and the feature that structure have the selectivity to the earthquake motions frequency and structure response have the close corresponding relation with instantaneous energy spectrum is pointed out.The main achievements of this paper could be summarized as follows:1. The theory of Wavelet transform is systematically expatiated and its basic feature and the application of engineering are pointed out. At the same time, the physical meanings and some critical problem of Hilbert-Huang transform are discussed further.2. From the analysis of earthquake records, the application of three transform and their contactions are analyzed. From the aspect of application, their applied fields in table are listed out. After the comparison of three transform, the difference of three performance contents is analyzed which including the extraction of the earthquake motion characteristics, the filter of earthquake signal, the frequency decomposition in the earthquake response, the solving of shear force between stories and the solution of dynamical equation. At the same time, their application future is analyzed.3. The dynamic analysis and calculation of multi-degree-of-freedom system are discussed. In order to get the displacement, velocity, acceleration of dynamic responseand the distribution of energy, a ten stories and two spans story shear model is analyzed and the results are compared by using Emipirical Mode Decomposition, Wavelet Decomposition and time-history analysis method. It showed that the conclusions of above analysis have the practical application significance to the design of aseismatic engineering.4. The response spectrum of the design of aseismatic is analyzed systematically. At the same time, the shortcoming of aseismatic response spectrum is discussed and the solution is gave out.5. The feature that structures have the selectivity to the earthquake motions frequency and structure response has the close corresponding relation with instantaneous energy spectrum is pointed out. In addition, the relation between response spectrum and HHT spectrum is analyzed. It is considered that the response spectrum have the close relation with HHT spectrum. And the conclusion of HHT and the conclusion of response spectrum is consistent and can verify mutually.All methods in this paper are realized with software Matlab6.5 under the plane of Microsoft Windows xp.