Wavelet-based Damage Detection of Steel Beam-Structures

Damage to structures is inevitable. Besides, the accumulation and spread of local damage can be a source of global damage; hence, the significance and necessity of monitoring the health of the structure. Wavelet analysis of structural responses is a method of damage detection with optimal performance in the time-frequency domain, which yields more information from the analyzed response of the structure in both time and frequency domains. As beams and columns are among the most fundamental structural elements and, expectably, the last elements to be damaged, it bears greater importance to identify damage in them than in other structural elements. This paper draws on modal analysis data of steel beams modeled in Abacus and a proposal of the wavelet analytical method to track different positions of damage along the beam, where the damages are defined as a decrease in the elastic modal. A decreasing shift in frequency values occurred in all modes due to damage. To detect the damage, the mode shape signal was defined as the damage mode shape and the differentiation between the healthy and the damage mode shapes as the wavelet transform input signal. The output signals from the wavelet analysis of the input signal indicated maximum and minimum relative fluctuations in different situations of damage so that the centers of damage were identified with zero error. The results also revealed that with increasing the severity of the damage, only the irregularity of the wavelet coefficients of that damage position increases.