應用希爾伯特-黃轉換以非線性度分析於結構健康診斷

Abstract

近年來發生許多重大地震事件，使得民眾與工程人員意識到結構健康診斷之重要性，希望能提供新的結構動態參數以供工程及研究人員觀察結構動態特性。本研究針對結構物受地震之安全狀態進行分析，以希爾伯特-黃轉換(Hilbert-Huang Transform, HHT)對於時頻分析之強大能力，分析結構受外力振動干擾下所測得訊號資料，利用時頻域放大函數(Time-Frequency domain Amplification Function, T.F.AF)中取出結構主頻寬度、主頻形心及能量歷時等，對結構進行非線性度的計算，探討結構行為與非線性度之間的關係。為了驗證本研究所使用的非線性度方法，本研究先利用midas GEN建立單自由度系統進行簡易的參數分析，在不同的外力震動下探討單自由度系統主頻之變化，接下來進一步使用中部科學工業園區管理局之縮尺結構模型進行振動台試驗，使用不同強度之TCU071地震紀錄逐步震動至破壞並紀錄其上部結構震動歷時，其中穿插white noise進行結構頻率識別。分析結果顯示，本研究可觀察出結構物弱層破壞後行為上的改變，並顯示結構破壞前後非線性度的變化與主頻及頂層加速度反應之間的關係。

In recent years, many catastrophic seismic events have occurred. To provide real-time structural dynamic parameters for engineering and researchers to observe structural dynamics, the study of the Hilbert-Huang Transform (HHT) is used to analyze the measured signal from the superstructure under the seismic excitation and a structure health monitoring method is developed. Time-Frequency domain Amplification Function (T.F.AF) is used for instantaneous frequency width, centroid of frequency and energy time-history of the structure. The health condition can be determined by degree of nonlinearity calculated from T.F.AF. In order to verify the proposed method, shaking table tests were conducted on the benchmark structure and examined afterwards. According to the analysis of the vibration signal recorded up to the time of collapse, it is shown that the change of structure behavior can be rapidly reflected, and the degree of nonlinearity can reflect the health condition of the structure before and after the collapse.