Abstract
In this study, we experimentally validated the normalized uniform load surface (NULS) curvature method, which has been developed recently to assess damage localization in beam-type structures. The normalization technique allows for the accurate assessment of damage localization with greater sensitivity irrespective of the damage location. In this study, damage to a simply supported beam was numerically and experimentally investigated on the basis of the changes in the NULS curvatures, which were estimated from the modal flexibility matrices obtained from the acceleration responses under an ambient excitation. Two damage scenarios were considered for the single damage case as well as the multiple damages case by reducing the bending stiffness (EI) of the affected element(s). Numerical simulations were performed using MATLAB as a preliminary step. During the validation experiments, a series of tests were performed. It was found that the damage locations could be identified successfully without any false-positive or false-negative detections using the proposed method. For comparison, the damage detection performances were compared with those of two other well-known methods based on the modal flexibility matrix, namely, the uniform load surface (ULS) method and the ULS curvature method. It was confirmed that the proposed method is more effective for investigating the damage locations of simply supported beams than the two conventional methods in terms of sensitivity to damage under measurement noise.
Highlights
Regular structural health monitoring is imperative for preventing catastrophic structural failure, for increasing the cost-effectiveness of maintaining existing structures, and for maintaining the serviceability of existing structures
The basic concept of these vibration-based methods is that changes in the boundary and physical characteristics of structures lead to changes in the structural modal parameters, that is, in the natural frequencies and mode shapes
The damage locations of a lab-scale supported beam model were numerically and experimentally investigated on the basis of the changes in the normalized uniform load surface (NULS) curvatures; these were estimated from the modal flexibility matrices obtained from the acceleration responses under an ambient excitation
Summary
Regular structural health monitoring is imperative for preventing catastrophic structural failure, for increasing the cost-effectiveness of maintaining existing structures, and for maintaining the serviceability of existing structures. During the past three decades, vibration-based damage detection methods based on various dynamic properties, such as the natural frequencies, mode shapes, mode shape curvatures, and modal flexibility matrices, have seen significant development. The basic concept of these vibration-based methods is that changes in the boundary and physical characteristics of structures lead to changes in the structural modal parameters, that is, in the natural frequencies and mode shapes. Damage localization can be performed by comparing the characteristics obtained from the modal parameters before and after damage. In the case of modal parameter-based damage detection techniques, the system identification method is crucial for obtaining the structural modal parameters. In order to be able to detect damage with precision, various signal processing and system identification techniques have been proposed. Nagarajaiah, Nagarajaiah and Basu, and Worden et al [1,2,3] have presented a number of time- and frequency-domain identification methods
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