| 摘要: | 本論文所發展之梁結構損傷的偵測依據檢測方式主要分為兩大類，一為逐點敲擊振動損傷偵測法、另一為移動荷載損傷偵測法。理論方法之研發與驗證採用鋁梁、H型鋼梁與預力混凝土梁做為實驗試體，量測的結構反應包含位移、速度與加速度、力脈衝等。逐點敲擊振動損傷偵測法為結合動力互易定理(Dynamic Reciprocal Theorem)、頻率域分解法(Frequency Domain Decomposition, FDD)、損傷指標(模態確認準則(Modal Assurance Criterion, MAC)、座標模態確認準則(Coordinate Modal Assurance Criterion, Co-MAC)、模態曲率差(Modal Curvature Change, MCC)與應變能變化(Change of Strain Energy, CSE)等)進行損傷識別，此方法的優點為運用少量的感測器即可取得結構的高階模態特徵，並運用於損傷指標計算上，分析結果顯示高階振型反應較具有識別損傷位置的能力。移動荷載損傷偵測法為結合經驗模態分解法(Empirical Mode Decomposition, EMD)、全相經驗模態分解法(Ensemble Empirical Mode Decomposition, EEMD)、撓度影響線與曲線擬合法進行損傷識別，此方法具有檢測快速、省時與量測設備簡便，且識別損傷時無須原始狀態資料等優點。此一新方法可有效處理量測訊號的雜訊而診斷出損傷位置。整體研究首先運用ANSYS有限元數值模型進行結構損傷特性的探討，藉此了解結構損傷後的結構變化特徵，將此作為理論方法的發展依據。並於實驗中觀察此些結構特徵(如頻率、振型、影響線)變化的共通性，進而達到有效而快速的損傷偵測定位能力。 Based on testing arrangements, two categories of damage diagnosis methods for beam structures were developed in this thesis. One is the point-by-point impacted vibration method and the other is the quasi-static moving loading method. The theoretical development and experimental verification were carried out on aluminum beams, H-shaped steel beams and pre-stressed concrete beams. The processed signals were the time histories of the displacement, velocity, acceleration responses of the beams and the impact force. The point-by-point impacted vibration method is combined with the Dynamic Reciprocal Theorem, the Frequency Domain Decomposition (FDD) method, and the Damage Index idea, which covers the Modal Assurance Criterion (MAC), the Coordinate Modal Assurance Criterion (Co-MAC), the Modal Curvature Change (MCC), and the Change of Strain Energy (CSE), etc. One of the advantages of this method is the capability of using fewer sensors to obtain higher order eigen-modes, which can be applied in the calculation of the damage index. Experimental results indicated that higher order vibration modes exhibit high potential in damage identification. The quasi-static moving loading method is combined with the Empirical Mode Decomposition (EMD) method, the Ensemble Empirical Mode Decomposition (EEMD) method, and the idea of the influence line of deflection curve and curve fitting. The main advantages of this method are fast and time-saving fulfillment, simple experimental setup and no need for the initial condition data for the tested structure. This new method can overcome the noisy influence and effectively identify the damage location. Throughout the study, the commercial software ANSYS was first used to explore the characteristics of damaged structures so that the change in structural characteristics can be understood. This would serve as the base for the theory development. Finally the common of the changes in the structural characteristics such as the frequencies, vibration modes, and influence lines, can be observed in the experiments so that the damage location can be identified in a fast and effective way. |
