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Structural Engineering and Mechanics Volume 36, Number 6, December20 2010 , pages 697-714 DOI: https://doi.org/10.12989/sem.2010.36.6.697 |
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Mode-by-mode evaluation of structural systems using a bandpass-HHT filtering approach |
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Jeng-Wen Lin
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| Abstract | ||
| This paper presents an improved version of the Hilbert-Huang transform (HHT) for the modal evaluation of structural systems or signals. In this improved HHT, a well-designed bandpass filter is used as preprocessing to separate and determine each mode of the signal for solving the inherent modemixing problem in HHT (i.e., empirical mode decomposition, EMD, associated with the Hilbert transform). A screening process is then applied to remove undesired intrinsic mode functions (IMFs) derived from the EMD of the signal\'s mode. A \"best\" IMF is selected in each screening process that utilizes the orthogonalization coefficient between the signal\'s mode and its IMFs. Through mode-by-mode signal filtering, parameters such as the modal frequency can be evaluated accurately when compared to the theoretical value. Time history of the identified modal frequency is available. Numerical results prove the efficiency of the proposed approach, showing relative errors 1.40%, 2.06%, and 1.46%, respectively, for the test cases of a benchmark structure in the lab, a simulated time-varying structural system, and of a linear superimposed cosine waves. | ||
| Key Words | ||
| bandpass filter; Hilbert-Huang transform; modal frequency; orthogonalization coefficient; signal filtering. | ||
| Address | ||
| Jeng-Wen Lin: Department of Civil Engineering, Feng Chia University, Taichung 40724, Taiwan | ||