應用不同地震於HHT結構健康監測方法

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题名:	應用不同地震於HHT結構健康監測方法
作者:	李信宏;Li, Hsin-Hong
贡献者:	土木工程學系
关键词:	希爾伯特-黃轉換法;結構安全診斷;HHT SHM
日期:	2019-07-24
上传时间:	2019-09-03 12:12:05 (UTC+8)
出版者:	國立中央大學
摘要:	傳統上，結構物損傷非破壞檢測，大多使用快速傅立葉轉換(Fast Fourier Transform)，但傅立葉方法以不隨時變的諧和函數作為基底函數來處理訊號，不符合非線性與非穩態系統訊號的基本要求。本研究以使用商業軟體ABAQUS建立三組不同損害程度的結構模型，地震力使用集集地震與花蓮外海地震進行動力分析試驗，利用希爾伯特-黃轉換(Hilbert-Huang Transform，HHT)的時頻分析技術，其具有局部隨適性與後待定基底函數兩個特性，定義上符合非穩態系統(Non-stationary System)的基本要求，常用於非穩態與非線性訊號資料分析上。從時頻譜可以看出訊號在時間域與頻率域上的能量分布，觀察到譜上能量會集中於某固定頻率值，可視為該結構模態的主頻，還可以觀察到物體隨時間變化的動態特性。研究方法使用HHT SHM分析方法中時頻放大函數T.F.AF與模態時間曲線MTVC兩個分析工具。T.F.AF將原始資料波形先轉換成波傳特性展現，結構受震時各波向動力特性可清楚展現出來。觀察時頻譜上能量與瞬時頻率的分布，於T.F.AF頻譜中擷取振動模態特質稱為模態時間曲線，在MTVC中可觀察到結構的安全參數訊息，藉由不同試驗條件，觀察結構特質的變化找出結構模態行為的細微差異，分析結構物受震後的結構安全狀態。 ;Traditionally, Nondestructive Testing of structural damage has mostly used Fast Fourier Transform, Fourier analysis using time invariant harmonic function as a basis function which is unable to meet the basic requirements of nonlinear and non-stationary signals. The commercial software ABAQUS was used in this research. Three sets of structural models with different degrees of damage were established. Earthquake history using Chi-Chi earthquake and Hualien offshore earthquake for dynamic analysis. The Hilbert Huang Transform (HHT), which is a time frequency analysis technique without a prior basis functions and local adaptability, the time-variant characteristic of the Hilbert Transform makes the analysis for the non-stationary system possible, is often used for nonlinear and non stationary signal analysis. From the time frequency spectrum, catching sight of the energy distribution of the signal in the time domain and the frequency domain. It is observed that the energy on the time frequency will be concentrated on a fixed frequency value, which can be regarded as the dominant frequency of the structural mode, and the dynamic characteristics of the structural as a function of time can also be observed. This study uses two analysis tools of the HHT SHM analysis method, the time-frequency amplification function (T.F.AF) and the modal time curve (MTVC). T.F.AF converts the raw data into a wave propagation characteristic, the dynamic characteristics of each phase of the structure will be apparently exhibited. Observing the distribution of energy and instantaneous frequency on the time frequency spectrum, and then the vibration mode characteristic in the T.F.AF spectrum is called MTVC. Observing the structural safety parameter information from the MTVC. Using different conditions, one can observe structural traits and find subtle differences in structural modal behavior which can be utilized to analyze the structural safety after earthquake.
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