利用改良式小波轉換技術進行結構損傷評估

Application of Modified Wavelet Transform for Damage Assessment of Civil Structure Using Vibration Measurements

薛汶(Wen Hsueh)

指導教授 ： 羅俊雄

國立臺灣大學/工學院/土木工程學研究所/碩士(2017年)

https://doi.org/10.6342/NTU201701121

摘要

對於時變系統的結構健康監測，小波轉換已被廣泛應用於取得局部時間的特徵相關訊息。本研究提出改良式小波轉換技術搭配可調式複數莫萊小波進行結構損傷評估，同時也提供較佳的時頻圖表示及簡化訊號重組。基於小波轉換得到的小波係數，本文介紹七種損傷指標包含：(1) Marginal spectrum, (2) Central frequency, (3) Pseudo-instantaneous frequency, (4) Unwrapped phase, (5) Novelty index, (6) Correlation, (7) Normalized component energy。本研究使用兩組振動台試驗的試體（雙塔鋼構架、三層樓鋼構架）以及兩棟實際結構（花蓮明禮國小、台中中興大學）來進行驗證，由分析結果顯示，本文提出之方法能夠取得結構物全域與局部特徵並有效進行結構損傷評估。

關鍵字

結構健康監測 ； 小波轉換 ； 可調式複數莫萊小波 ； 結構損傷評估 ； 結構損傷部位識別

並列摘要

For detecting transient signals and time-varying systems, wavelet transform has been used as a signal pattern recognition method for feature extraction. In this study, dynamic response data of structure using modified complex Morlet wavelet with variable central frequency (MCMW+VCF) is used to establish a time-frequency representation of measurement for modal parameter estimation and system damage identification. The proposed wavelet transform (WT) provides a better representation in generating scalogram than using general wavelet transform, besides, the proposed WT can simplify the choice of wavelet parameters and signal reconstruction. Based on the wavelet coefficients, several damage assessment algorithms will be described, which include: (1) Marginal spectrum, (2) Central frequency, (3) Pseudo-instantaneous frequency, (4) Unwrapped phase, (5) Novelty index, (6) Correlation, and (7) Normalized component energy. Seismic response data collected from two lab experiments, a twin tower steel structure and two 3-story steel structures, under a series of both white noise as well as earthquake excitation back to back will be used to demonstrate the proposed algorithms. Also, two field experiments, seismic response of Mingli elementary school and NCHU Civil & Environmental Engineering Building, will be used for the verification, too. The performance of the proposed algorithms is capable for damage detection and localization.

並列關鍵字

structural health monitoring ； wavelet transform ； modified complex Morlet wavelet ； damage detection ； damage localization

參考文獻

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