EMD訊號擷取模式及HHT頻譜解析 圖形判讀準則建立與混凝土橋損傷驗證

The study of construction and verification in EMD signal acquisition model and the judgment rules of HHT spectrum in damaged concrete bridges

陳柏麟(Po-Lin Chen)

指導教授 ： 張達德

中原大學/工學院/土木工程研究所/博士(2009年)

https://doi.org/10.6840/cycu200900688

摘要

經驗模態分解法（EMD）與希爾伯特黃轉換（HHT）頻譜解析理論自發展以來，廣為各界頻譜解析研究人員所討論。 EMD雖具有訊號分解的特殊功能，但須仰賴解析者的經驗設定時間尺度以進行訊號分解。而解析所得之分量經常會產生嚴重的模態混合或主振模態分散，無法在單一分量中獲得完整主振模態，這樣的結果將使得訊號分解失去意義。一旦訊號分解失去意義，接下來的
HHT頻譜圖形的解析就失去其判讀的價值。
本研究為了有效解決EMD訊號分解所衍生的問題，並建立具體的HHT頻譜解析圖形判讀準則，先於實驗室進行訊號模擬分析、實驗室振動試驗模擬分析，並於雲林興南大橋進行現地振動量測試驗，以獲得實際的橋樑振動訊號進行初步的解析與探討。針對初期試驗所得成果及所發現的問題深入研究，並建立EMD訊號擷取模式及HHT頻譜解析圖形判讀準則。最終，分別以新濱二號橋以及雲林興南大橋沖刷橋墩系統之振動訊號為實例進行解析與驗證。
由驗證結果可證實，藉由EMD訊號擷取模式的建立，可以有效率且正確的在單一分量中獲得量測對象的振動模態。此突破不但提供研究人員一套可依循
參考的訊號分解模式，使得EMD訊號分解理論得以有效被應用。
HHT頻譜解析圖形的判讀準則與程序的具體化，雖屬初步的概念，但其中針對IMF分量的選用、可判讀區間的檢視、模態混合與頻率損失區間的判別、HHT頻譜圖中的強迫振動區間與自然振動區間判斷、邊際頻譜圖中雙峰現現象以及HHT頻譜圖與邊際頻譜圖的交叉比對等皆提出可供參考的判讀方法。

關鍵字

經驗模態分解法 ； 希爾伯特黃轉換 ； 主振模態分散 ； EMD訊號擷取模式 ； HHT頻譜解析圖形判讀準則

並列摘要

Empirical Mode Decomposition （EMD）as well as Hilbert Huang Transform（HHT）has been widely discussed by the spectrum researchers since the theory of spectrum analysis developed. Function of decomposing the signal as it carries, EMD counts on the analyst’s experience to set the timescale in the process of decomposing the signal. However, the analytical component often brings about the severe mixed mode or dispersion of the main vibrating mode; it is unable to gain the completely main vibrating mode in a single component. Such a result will make not only the
decomposition of signal meaningless but the following HHT spectrum analysis
valueless in judgment.
In order to solve the problem caused by EMD efficiently and establish the concrete criteria in judging the HHT graph, the research was first done in the lab to go about the simulated analysis of the signal and of the vibrating test as well. Furthermore, the vibrating test proceeding at the Shin Nan Bridge was done so as to gain the really vibrating signal from the bridge, and it could be used to do the initial analysis and discussion. Based on the testing consequence at the early stage, the research went on in detail and established the signal acquisition mode in EMD and the judgment criteria of the spectrum analysis graph in HHT. In the end, the vibrating signal of the scoured pier system separately at the Shin Pin Bridge and the Shin Nan Bridge could be used to carry out the analysis and test.
As demonstrated by the testing consequence, it can be efficient and correct to gain the vibrating mode of the measured object over the single component. The breakthrough not only offers the researchers a set of reference to the signal
decomposition mode to follow but makes EMD signal acquisition mode efficiently
applied.
Initial concept though it is, the judgment criteria of the HHT graph along with its established procedure shows the measures of judgment, particularly in IMF options, inspections of judgment range, judgment between the mixed mode and the section of frequency loss, judgment between the forced vibration and free vibration in HHT, two-peak phenomenon in the marginal spectrum, and cross comparison
between HHT and the marginal spectrum.

並列關鍵字

Empirical Mode Decomposition（EMD） ； The main vibrating mode ； EMD signal acquisition mode ； The judgment criteria of the HHT ； Hilbert Huang Transform（HHT）

參考文獻

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