本論文針對新建初完工的單塔脊背橋，利用全橋動態車載試驗，分析橋梁結構放大特性，而橋梁結構受振反應往往具有非線性及非穩態性，在傅利葉上使用不隨時變的諧和函數作為基底函數的訊號處理方法，不符合非線性與非穩態系統訊號的基本要求。為了進行橋梁損傷的非破壞檢測，利用希爾伯特-黃轉換(Hilbert-Huang Transform，HHT)新穎的時頻分析技術，其具有後待定基底函數與局部隨適性的特性，常用於非線性且非穩態訊號分析上，可展現訊號在時間域與頻率域上的能量分布，觀察物體隨時間變化之動態特性。來分析結構物經動態車載試驗資料，探討橋梁結構受震後的結構安全狀態，並借助瞬時頻率來解讀結構體振動特性變化。 研究方法為HHT SHM分析法，其中兩個分析工具，時頻放大函數T.F.AF與模態時間曲線MTVC。將外力波形轉換成波傳特性相關展現，結構受震時各波相動力特性會在T.F.AF上展現出來，透過觀察時頻譜上能量與瞬時頻率的分布，找出時變系統振動行為，接著於T.F.AF頻譜中擷取振動模態特質稱為MTVC。MTVC中有豐富的結構安全參數訊息，比對不同試驗條件，估算結構特質的變化情形找出結構模態行為的細微差異。 ;This study uses Dynamic Vehicle Test to analyze the amplification characteristics of the bridge structure which is just completed. However, the bridge structure responses of vibration are often nonlinear and non-stationary. Fourier analysis using time invarint harmonic function as a basis function which is unable to meet the basic requirements of nonlinear and non-stationary signals. In order to carry out non-destructive testing of bridge damage, the Hilbert-Huang Transform (HHT), which is a time-frequency analysis technique without a prior basis functions and local adaptability, is often used for nonlinear and non-stationary signal analysis, it can show the energy distribution of the signal in the time domain and frequency domain and observe the dynamic characteristics of the object changing with time. This study uses two analysis tools of the HHT SHM analysis method, the time-frequency amplification function (TFAF) and the modal time curve (MTVC). Converting the external force waveform into a wave-propagation characteristic, the dynamic characteristics of each phase of the structure will be exhibited on the TFAF, and the time-varying system vibration behavior will be found by observing the distribution of energy and instantaneous frequency on the frequency spectrum, and then the vibration mode characteristic in the TFAF spectrum is called MTVC. MTVC has a wealth of structural safety parameter information. It compares the external conditions of different tests, estimates structural traits and finds subtle differences in structural modal behavior.
