A Fast and Direct Algorithm for Structural Damage Identification Based on Modified Modal Residual Force

Abstract eng:
Structural damage detection is the most important part of a structural health monitoring program which has been devoted to damage identification by analyzing recorded data from monitored structure. Among different methods which have been proposed for damage identification, vibration-based methods are more preferred. This is due to a rational and one-to-one relation which exists between vibrational data and damage features. Despite the availability of various vibration-based methods which use different computational strategies for damage localization and quantification, proposing fast and practical approach for identifying structural damages is more desirable in the field of structural maintenance. In this paper, a fast damage prognosis method is proposed to detect and estimate structural damages in shear frame structures. The basic idea of the proposed algorithm relies on turning the tri-diagonal stiffness matrix of a shear frame into a diagonal matrix by means of the diagonalization method. This transform results in a modification on the modal residual force vector which causes to formulate a direct damage detection approach. Finally, the computation of damage severity is defined and established by a fast, simple, and direct concept which is able to quantify damage magnitude in a high level of accuracy. The important advantages of the presented algorithm are its simplicity and fast speed in the determination of damage severity in comparison with soft-computing- and optimization-based damage identification methods. To demonstrate the efficiency and robustness of the proposed approach, a 25-story shear frame was numerically considered with different damage scenarios. In addition, the performance of the presented approach was demonstrated when the measured modal data is contaminated with different levels of random noises. In order to validate the application of the damage diagnosis method in real structures, a five-story building structure on a shaking table was considered. Most of the obtained results from the numerical and experimental studies show the good performance and reliability of the presented method for damage identification and estimation and introduced it as a fast and powerful method for damage diagnosis in engineering structures that have a tri-diagonal stiffness matrix.

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