臺灣博碩士論文加值系統

隨著結構物的監測技術和系統識別方法日漸進步，結構健康監測已成為工程界與學界關注的重要領域。而其中大型結構物的系統識別常常藉由環境微振量測來完成，但由於微振量測僅能得到結構的輸出反應，無法得知其輸入外力，因此需要僅以結構輸出反應求得模態參數之系統識別方法，一般稱為工作模態分析(OMA)，例如峰值挑選法、隨機子空間識別法(SSI)和頻率域分解法(FDD)等。
本文針對頻率域分解法進行深入探討，改善其分解後振態PSD轉至時間域後的識別方法，以得到較佳的模態參數識別結果。此外，為了瞭解FDD應用在不同類型結構時之最佳化參數設定，本文先針對有理論解之數值範例模型進行系統識別與結果探討，再進而應用至實際的房屋及橋梁結構在環境振動下之模態參數識別，並與SSI的分析結果進行比對。識別結果顯示FDD對於測試的範例都可以得到與理論解或與SSI相近的模態參數，表示FDD是一個有效的OMA方法，而且FDD還具有計算簡單快速、對於頻率相近的振態可以分離開來識別的優點。

With the advance of monitoring technology and system identification of structures, structural health monitoring has become an important field in both academic and industrial circles. In recent years, system identification of large structures is often accomplished based on ambient vibration measurements. However, only the output response of the structure can be obtained from ambient vibration measurements. Without any information about the input forces, output-only modal analysis, which is also called operational modal analysis (OMA), is needed to identify the modal parameters of structures. Several OMA methods have been developed and applied to various types of structures, for example, the peak picking method, the stochastic subspace identification techniques (SSI) and the frequency domain decomposition method (FDD), etc.
In this study, the frequency domain decomposition method is examined and exploited in depth. After converting the decomposed SDOF power spectral density function (PSD) to the time domain, the modal properties are found using an improved identification method. Furthermore, in order to evaluate the optimal parameters in the FDD method for different types of structures, numerical simulation models are analyzed first and the identified modal properties are compared with the exact values. Then the modal analysis of real building and bridge structures are carried out using FDD based on ambient vibration measurements, and the results are compared with those using SSI. This study shows that all of the identified modal parameters by FDD are close to the exact values or the results using SSI, which means that FDD is an effective method of OMA. In addition, the computation of FDD is relatively simple and fast compared to other OMA methods. The modes with close frequencies can be separated and readily identified by FDD.

摘要 ...............................................................................................................................i
ABSTRACT...................................................................................................................ii
誌謝 ............................................................................................................................ iii
目錄 .....................................................................................................................iv
表目錄 .........................................................................................................................vi
圖目錄 ...................................................................................................................... viii
第一章 緒論 ................................................................................................................1
1.1 研究背景與動機............................................................................................1
1.2 文獻回顧........................................................................................................2
1.3 研究目的........................................................................................................3
1.4 研究方法........................................................................................................4
1.5 論文架構........................................................................................................5
第二章 頻率域分解法的基本原理 ..........................................................................6
2.1 隨機振動理論................................................................................................6
2.1.1 相關函數.............................................................................................6
2.1.2 功率譜密度函數...............................................................................10
2.1.3 頻率響應函數...................................................................................11
2.2 奇異值分解(Singular Value Decomposition, SVD) ....................................13
2.3 頻率域分解法(Frequency Domain Decomposition, FDD)..........................14
2.4 亞伯拉罕時間域識別法..............................................................................17
2.5 頻率域分解法的NFFT參數探討..............................................................22
第三章 結構數值範例分析 ....................................................................................31
3.1 平面剛架結構..............................................................................................31
3.2 空間剛架結構..............................................................................................32
v
3.2.1 正方形平面之空間剛架...................................................................32
3.2.2 矩形平面之空間剛架.......................................................................34
3.3 校舍結構......................................................................................................35
3.3.1 白訊外力下之識別結果...................................................................36
3.3.2 地震力下之識別結果.......................................................................37
3.4 橋梁結構......................................................................................................38
3.4.1 白訊外力下之識別結果...................................................................38
3.4.2 地震力下之識別結果.......................................................................40
第四章 實際房屋結構之量測與識別 ....................................................................118
4.1 公誠國小忠孝樓........................................................................................118
4.2 雲林國小A棟教學大樓...........................................................................119
4.3 雲科大工程三館........................................................................................121
第五章 橋梁結構之識別 ........................................................................................154
5.1 南投縣集鹿大橋........................................................................................154
5.1.1 鋼纜.................................................................................................154
5.1.2 橋面.................................................................................................155
5.2 高屏溪斜張橋............................................................................................156
5.2.1 鋼纜.................................................................................................156
5.2.2 橋面.................................................................................................158
第六章 結論與建議 ..............................................................................................193
6.1 結論............................................................................................................193
6.2 建議............................................................................................................194
參考文獻 ..................................................................................................................195

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