Sensitivity Analyses of Structural Damage Indicators and Experimental Validations

The vibration-based damage detection (VBDD) has been widely used in structural health monitoring (SHM). However, different damage indicators have different effects on SHM. It is necessary to analyze the sensitivity of structural damage indicators to study the correlation between these indicators and damages. In this paper, the sensitivities of the mode shape, modal strain energy (MSE) and strain mode are numerically studied and experimentally validated. The damage is simulated by the reduction in the cross-sectional area of the rods of a 3-D steel frame. The sensitivity of the three damage indicators are obtained and compared by using the finite element (FE) analyses of the frame; the modal parameters are obtained through the experimental modal analysis, and the sensitivity of the three damage indicators are calculated to validate whether they could identify the structural damage. The results indicate that, generally, the sensitivity of the modal strain is the highest, followed by the MSE, and the sensitivity of the mode shape is the lowest. Nevertheless, the MSE shows high sensitivity in the cases of multiple damages. The sensitivity of the damage indicators varies for different damage locations; the sensitivity decreases from the mid span to the end of the steel frame. The above results provide a theoretical basis for the selection of damage indicators in the damage detection.