對稱與不對稱結構之系統識別與試驗

System Identification and Testing of Symmetric and Unsymmetric Structures

陳建德(Jian-De Chen)

指導教授 ： 尹世洵

國立臺北科技大學/工程學院/土木與防災研究所/碩士(2010年)

https://doi.org/10.6841/NTUT.2010.00300

摘要

本文首先利用SAP2000建立一結構模型進行數值模擬，根據模擬中得到的歷時反應，以ARX模型系統識別，並與模態分析所得到的模態參數相比較，證明了系統識別方法的正確性。接下來，考慮不對稱結構所發生之扭轉效應，以實際結構試驗歷時反應資料來進行系統參數識別，可判別出結構產生的扭轉變化。同時，本試驗採用傳統加速度(壓電式加速度計)與先進加速度計(MEMS加速度計)作為量測工具，並利用量測資料進行系統識別，比較兩者之性能。最後，我們利用四層樓小型鋼構模型，在無特殊外力干擾的情況下，量測結構物因環境效應作用下的微動態特性，將微振量測所得到的歷時資料，進行系統識別求取結構物之模態參數與強迫振動試驗結果作比較，並針對各種不同損壞組合之結構模型，進行結構模態參數識別與損壞指標計算，證實了利用微振量測試驗資料能有效地得知損壞位置。

關鍵字

系統識別 ； ARX模型 ； 微振量測 ； 結構健康檢測

並列摘要

First, the study numerically simulates a structure by use of SAP2000. According to the structural time response calculated from the simulation, the modal parameters are identified using ARX-model system identification, and then compared with the ones obtained from modal analysis. The comparison demonstrates the accuracy of the used system identification method. Next, we consider a unsymmetric structure which presents torsional behavior, and collect the time response of the structure in a real test. We find that the torsional mode can be detected by applying system identification to the collected data. Meanwhile,traditional accelerometers ( piezoelectric accelerometers ) and advanced accelerometers ( MEMS accelerometers ) are used in the test. The performance of the two sensors are compared. Finally, the modal parameters of a small-scale four-story steel frame structure are identified using ambient vibration records of the structure on which no external forces are acting. The results are compared with the ones obtained using the forced vibration records. Moreover, We conduct system identification for the structure with different damage combinations. Based on the identified mode shapes, the damage detection index ( inter-story drift mode shape, IDMS ) for each damaged structure is calculated. The results show that the system identification of ambient vibration records as well as the calculated damage detection index can effectively detect damage locations.

並列關鍵字

system identification ； ARX model ； ambient vibration tests ； structure health monitoring

參考文獻

[25] 吳艮任，小型鋼構架之系統識別與試驗，國立台北科技大學土木與防災研究所碩士論文，台北，2009。

[28] 施建良，小型鋼構架之結構健康檢測，國立台北科技大學土木與防災研究所碩士論文，台北，2009。

[1] A. K. Mittal and Ashok K. Jain,“Effective strength eccentricity concept for inelastic analysis of asymmetric structures.” Earthquake Engineering and Structural Dynamics, Vol. 24, 1995 , pp.69-84.

[3] Brown, D. L., Allemang, R. J., Zimmerman, R. and Mergeay, M. “Parameter estimation techniques for modal analysis,” SAE Paper, Number 790221, 1979.

[4] Farrar, C.R. and James, G.H., “System identification from ambient vibration measurements on a bridge,” Journal of Sound and Vibration,205（1）, 1997, pp. 1-18,.