Damage Detection Method of Simply Supported Beams Based on Difference of Nearby Difference Curvature Index

Abstract

In order to improve the effectiveness and convenience of damage identification of two-span continuous beams, a new damage identification index <I>D</I>_i based on the deflection data of beam under concentrated load, which takes local flexural stiffness and shear stiffness as damage identification parameter, was proposed. The damage detection method based on <I>D</I>_i includes four main steps: arranging vertical deflection measurement points at equal intervals on the beam body and applying a concentrated load <I>F</I> at the mid span position of one of the spans. After measuring the <i>y</i>_i value at each measurement point, the differential deflection curvature value 1/<i>ρ</i>_ican be calculated; After obtaining specific values of <I>D</I>_iaccording to the definition, a graph with <I>D</I>_i as the vertical coordinate and the positions of each measuring point on the longitudinal axis of the beam as the horizontal coordinate can be drawn; The mutation position on the graph can indicate the location of the damage: if the mutation starts from point <i>j</i>, it indicates that the damage occurs in the area between measurement points <i>j</i>+1 and <i>j</i>+2; By selecting any two values from <I>D</I>_i-1, <I>D</I>_i, and <I>D</I>_i+1 and solving the corresponding definition equation simultaneously, the degree of beam damage characterized by the relative change in local stiffness can be determined. The results of numerical example validation indicate that this method has good damage identification performance.