利用振動訊號診斷橋樑結構損壞之研究

A Study on Diagnosing Damages of Bridges using Vibration Signals

璩顥(Hau Chiu)

指導教授 ： 黎文龍

國立臺北科技大學/機電學院/製造科技研究所/碩士(2011年)

摘要

本研究主要利用能量損耗的觀念，進行橋樑結構健康度的診斷，並採用新近發展的結構耗能鑑別方法。結構耗能法以激振力當作輸入訊號施加於系統之基座，再量測該系統之輸出訊號的穩態響應，將輸入訊號與輸出訊號做乘積調變，找到調變後訊號之傅立葉係數，計算出系統耗能並且反推結構體本身之勁度矩陣，最後觀察橋樑結構損壞程度不同所產生結構勁度的變化，達到診斷橋樑的效果。
在動態模擬中，觀察橋樑結構體在不同損壞程度下的結構特性。由結果顯示，結構體的能量消耗隨著不同的損壞程度有明顯的變化，隨著損壞指標越低有上升的趨勢，而結構體的勁度值也同樣隨著不同的損壞程度有明顯的變化，將隨著損壞指標越低有下降的趨勢。
在實驗驗證方面，本研究製作近似橋樑之結構模型，分別在不同的損壞情況下量測結構動態特性，並且對橋樑結構體進行鑑別。由實驗結果顯示，從能量消耗及勁度值來觀察，幾乎都與動態模擬的趨勢相同，所以比起自然頻率的變化，從能量消耗及結構勁度來判別結構體損壞有更好的準確性。

關鍵字

橋樑結構 ； 結構能量損耗 ； 結構診斷

並列摘要

The variety of damage detection methods, modal-based techniques have been the most widely investigated due to their global nature and simplicity. Modal-based methods exploit the observable variation in modal parameters before and after the presence of defects in the structure. The present papers is a method for measuring the damping ratio of a structural system that is under base excitations. The method is accomplished by processing the response signal with respect to that of the input. In other words, one is to measure the responses of the system, which is excited by an input sinusoidal signal. Once the response signal is obtained, it can be modulated by two different reference signals. The required dissipative energy, damping ratio, or even system damping can be thus extracted from the modulated signal by the given equation through its Fourier coefficients. In addition, the current method does not require the system damping to be small and valid for a wide range of damping ratios. and valid for a wide range of damping ratios.

並列關鍵字

Bridges ； Structural dissipative energy ； Structural diagnosis

參考文獻

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