Comparison Study of the Location-Related Damage Sensitivity and Structural Damage Index with Sensitivity Enhancement for Beam Structure

The primary requirement for vibration-based structural damage identification is to develop the damage index with higher damage sensitivity. Although it is believed that higher order mode means more sensitivity to damage, what is the quantitative relationship between damage sensitivity of different orders and how to carry out multi-mode fusion lack theoretical guidance. This paper implements the comparison study of the location-related damage sensitivity for different mode shape curvatures and then proposes a structural damage index with sensitivity enhancement for beam structure. First, the damage sensitivity of the mode shape curvature of beam structures at different orders is compared in theory. It reveals that the damage sensitivity is location-dependent, and the second-order mode in the even 16.6% region is more sensitive than the third-order mode in the simply supported beam. Second, a structural damage index with sensitivity enhancement for beam structure is proposed according to the relationship between the damage sensitivity of mode shape curvature at different orders and locations. Third, a simply supported beam model and a steel stringer bridge model with multiple main girders are both investigated to illustrate the comparison results of the damage sensitivity at different orders and the advantages of the proposed structural damage index. It shows that the confused damage sensitivities are very common between different mode orders, the sensitivity-enhanced damage index that considers the damage location always shows certain degree of improvement of damage indication ability in different damage areas. Finally, the effectiveness and accessibility of the proposed method are verified by a simply supported beam experiment.