模態曲率應用於混凝土梁損傷檢測之初步研究

Preliminary Study on Damage Assessment of Concrete Beams using Modal Curvature

謝逸儒(Yi-Ju Hsieh)

指導教授 ： 余志鵬

朝陽科技大學/理工學院/營建工程系/碩士(2007年)

摘要

近年來，公共工程建設已從大量興建之形態逐漸轉換成全面進行維修補強之形態。民間部份受損的房屋也以修繕改建的方式來代替傳統拆除重建之做法。台灣位處地震頻繁、颱風多的地理位置上，建築物遭受震害、土石流等大地災害機率相對極高，所以發展出快速檢測評估結構物之方法，為現今迫切之研究課題。
本論文藉由有限元素數值模型進行參數研究，針對模態位移進行模態曲率之計算，由模態振形識別出結構之損傷指標與有效勁度。並由數值模型之結果歸納出以模態曲率判斷缺陷變化之規則性，最後再運用彈性互易定理觀念以實體試驗進行驗證方法之可行性。
初步研究結果顯示以模態曲率方法計算有限元素模擬缺陷之反應時，訊號可清楚地顯示出缺陷之情況，但該方法於實驗中應用時，卻遭遇量測訊號不明確，且互易定理之量測觀念無法應用之問題。因此，後續若有延續相關研究，仍需針對實驗訊號可靠度加以探討改良之方法。

關鍵字

混凝土 ； 模態曲率 ； 損傷檢測

並列摘要

In recent years, the demand of assessing and rehabilitating infrastructures and/or urban buildings has increased. To repair and strengthen a damaged structure is sometimes a more efficient way than to rebuild a new one. Taiwan is potentially threatened by various natural hazards such as Typhoons and Earthquakes, the development of efficient assessment techniques is thus a worth topic to be investigated.

In this work, parametric studies were carried out using numerical data obtained from Finite Element programs in which modal curvatures are computed to recover the effective stiffness of a specimen. Based on the numerical results, patterns regarding judging defect types and locations from modal curvatures are summarized. Reciprocity theorem was also employed in the experimental tests to simplify the procedure.

It is preliminarily concluded that defects can be effectively identified through modal curvature data as long as test signals are reliably acquired while this study did somehow encounter difficulties in data acquisitions with our current piezoelectric equipments. Further improvement in test repeatability should be done for this methodology to be practically used in field tests.

並列關鍵字

modal curvature ； concrete ； damage assessment

參考文獻

1.Wahab, M. M., and Roeck, G., “Damage Detection in Bridges Using Modal Curvatures: Application to A Real Damage Scenario,” Journal of Sound and Vibration, Vol. 2, No. 226, pp. 217-235, 1999.

3.Bendat, J. S., and Piersol, A. G., “Engineering Applications of Correlation and Spectral Analysis”, New York: Wiley (1993).

5.American Concrete Institute ACI 1998 “Nondestructive test methods for evaluation of concrete in structures.” ACI 228, 2R-98, Detroit.

6.Pandey, A. K., Biswas, M., and Samman, M. M., “Damage Detection from Changes in Curvature More Shapes,” Journal of Sound and Vibration, Vol. 2, No. 145, pp. 321-332, 1991.

7.Wahab, M. M., Roeck, G., and Peters, B., “Parameterization of Damage in Reinforced Concrete Structures Using Model Updating,” Journal of Sound and Vibration, Vol. 4, No. 228, pp. 717-730, 1999.