摘要
摘要 目前土木工程上對於訊號處理仍以傅立葉轉換為主，但是這個方法僅適用於線性與穩態的結構振動現象，故對於非線性系統所產生的非穩態訊號而言，其分析結果已喪失訊號本身所代表的物理意義。此外，於進行橋梁動態載重試驗的過程中，無法避免四周環境所產生的擾動與各種雜訊，因此所獲得的振動訊號會存在模態混合現象。 本研究主要目的乃是期望能有效排除模態混合現象產生，因此本研究嘗試以經驗模態分解法(EMD)與間斷性準則為主要研究方法，藉由其特殊的複合訊號分解功能，企圖將橋梁振動訊號加以淨化，使訊號更加潔淨與清晰。研究過程中採用新濱二號橋、興南橋及捷運橋梁之橋梁動態載重試驗資料為研究實例，於EMD分解過程中分別採用CE(Component from Extrema)與CEI(Component from Extrema with Intermittency Testing)兩種訊號分解模式與不做訊號分解模式進行探討比對，同時於CEI模式中亦針對不同的間斷性準則限制條件進行變化，探討間斷性準則限制值修正模式(n1-Δ)於橋梁振動訊號淨化之適用性，最終以希爾伯特-黃轉換(HHT)為訊號解析工具，分別比較分析各分解模式所獲得結果之差異與優劣。 根據研究結果發現，間斷性準則限制值修正模式確有其存之必要性，且由新濱二號橋與興南橋訊號分析結果得知，CEI-15模式所得的淨化效果最佳；由捷運橋梁訊號分析結果發現，CEI-30模式所得的淨化效果最佳。
並列摘要
ABSTRACT Today, civil engineers still mainly use Fast Fourier transform to analyze the behavior of structures, but this method is only suitable for the structure vibration phenomenon of the linear and the stationary, so it produces to be stationary signals and speech to non-linear system, its analysis result has already lost the physics meaning represented of the signals. Furthermore, in carrying on the course of live load test of the bridge, it is unable to avoid the perturbation produced of the environment and various kinds of miscellaneous signals all around, so there will be mode mixing phenomenon in the vibration signals. This main purpose of research is to expect to be able to get rid of the mode mixing phenomenon effectively, therefore, it is main research try to with the Empirical Mode Decomposition(EMD) and Intermittence Criterion in this research, by means of decomposing function of special complex signals, attempt to purify the vibration signals of the bridge, make the signals cleaner and clearer. Adopt the live load test data of Shin Bin No.2 Bridge，Shing Nen Bridge and Metro Bridge the in the course, in EMD decomposition process adopt CE(Component from Extrema) and CEI(Component from Extrema with Intermittency Testing) two signal decomposition modes and don’t make signal decomposition mode to probe and compare,and change to different Intermittency Criterion limiting conditions in CEI mode at the same time, probe into the revise mode(n1-Δ) of Intermittency Criterion limiting value in the suitability that vibration signals purifies of the bridge, finally, using Hilbert-Huang Transform(HHT) to compare with results of different decomposition modes. According to the results of this study, the revise mode of Intermittency Criterion limiting value really is necessity to store, and is learnt analysis results of the signals of Shin Bin No.2 Bridge and, Shing Nen Bridge the purification results of CEI-15 is the best; from the Metro Bridge signals analysis of results, we can find, the purification results of CEI-30 mode is the best.