Damage Localization of RC Beams via Wavelet Analysis of Noise Contaminated Modal Curvatures

Abstract

In this paper, the location of single, double, and triple damage scenarios in reinforced concrete (RC) beams are assessed using the Wavelet transform coefficient. To achieve this goal, the numerical models of RC concrete beams were conducted based on the experimental specimens. The mode shapes and corresponding modal curvatures of the RC beam models in damaged and undamaged status were considered as input signals in Wavelet transform. By considering the Wavelet coefficient as damage index, Daubechies, Biorthogonal, and Reverse Biorthogonal Wavelet families were compared to select the most proper one to identify damage locations. Moreover, various sampling distances and their influence on the damage index were studied. In order to simulate the practical situations, two kinds of noises were added to modal data and then denoised by Wavelet analysis to check the proposed damage index in noisy conditions. The results revealed that among the wavelet families, rbio2.4 and rbio2.2 outperform others in detecting damage locations using mode shapes and modal curvatures, respectively. As expected, the sensitivity of modal curvatures to different damage scenarios is more the mode shapes. By increasing sampling distances from 25 mm to 100 mm, the accuracy of the proposed damage index reduces. In order to eliminate boundary effects, it is necessary to use windowing techniques. Applying Wavelet denoising methods on noise-contaminated modal curvatures leads to proper damage localization in both types of noises.