Structural damage diagnosis using modal data

This paper presents a global algorithm for damage assessment of structures, based on a parameter estimation method, using the finite element and measured modal response of the structure. Damage is considered as a localized reduction in structural stiffness. Unmeasured parts of the mode shapes of a structure are characterized as a function of the structural parameter and measured parts of the mode shape. Elemental damage equations, which relate the partially measured mode shapes of a damaged structure to a change in structural parameters, are developed using incomplete measured mode shapes. These equations are solved to find the changes in structural parameters, utilizing an optimization method. Noise polluted data are used through Monte Carlo simulation to investigate the sensitivity of the proposed method to errors present in the measured modal data. The algorithm is verified in a numerical simulation environment using a planer truss and frame. Results show the good ability of this method to detect any damage of structures in the presence of errors in the acquired data.