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Smart Structures and Systems Volume 4, Number 5, September 2008 , pages 605-628 DOI: https://doi.org/10.12989/sss.2008.4.5.605 |
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Damage detection in beam-like structures using deflections obtained by modal flexibility matrices |
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Ki-Young Koo, Jong-Jae Lee, Chung-Bang Yun and Jeong-Tae Kim
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| Abstract | ||
| In bridge structures, damage may induce an additional deflection which may naturally contain essential information about the damage. However, inverse mapping from the damage-induced deflection to the actual damage location and severity is generally complex, particularly for statically indeterminate systems. In this paper, a new load concept, called the positive-bending-inspection-load (PBIL) is proposed to construct a simple inverse mapping from the damage-induced deflection to the actual damage location. A PBIL for an inspection region is defined as a load or a system of loads which guarantees the bending moment to be positive in the inspection region. From the theoretical investigations, it was proven that the damage-induced chord-wise deflection (DI-CD) has the maximum value with the abrupt change in its slope at the damage location under a PBIL. Hence, a novel damage localization method is proposed based on the DI-CD under a PBIL. The procedure may be summarized as: (1) identification of the modal flexibility matrices from acceleration measurements, (2) design for a PBIL for an inspection region of interest in a structure, (3) calculation of the chord-wise deflections for the PBIL using the modal flexibility matrices, and (4) damage localization by finding the location with the maximum DI-CD with the abrupt change in its slope within the inspection region. Procedures from (2)-(4) can be repeated for several inspection regions to cover the whole structure complementarily. Numerical verification studies were carried out on a simply supported beam and a three-span continuous beam model. Experimental verification study was also carried out on a two-span continuous beam structure with a steel box-girder. It was found that the proposed method can identify the damage existence and damage location for small damage cases with narrow cuts at the bottom flange. | ||
| Key Words | ||
| beam-like structures; deflection-based damage detection; modal flexibility; positive bending loads; outlier analysis; measurement noise; experiments. | ||
| Address | ||
| Ki-Young Koo; Department of Civil & Environmental Engineering, KAIST, 373-1, Gusong-dong, Yusong-gu, Daejeon, Korea Jong-Jae Lee; Civil & Environmental Engineering, Sejong University, 98 Gunja-dong, Kwangjin-gu, Seoul, Korea Chung-Bang Yun; Department of Civil & Environmental Engineering, KAIST, 373-1, Gusong-dong, Yusong-gu, Daejeon, Korea Jeong-Tae Kim; Department of Ocean Engineering, Pukyong National University, 599-1 Daeyeon-dong, Namgu, Busan, Korea | ||