Damage Identification of Structures Including System Uncertainties and Measurement Noise

This paper proposes a statistical method for the damage identification of structures based on the measured acceleration response with reference to an analytical model. Uncertainties in the system parameters, such as the structural parameters of the finite element model, the excitation force acting on the structure, and the measured acceleration response from the perturbed state of the structure, are discussed and they are included in the study of the damage identification. Each of these uncertainties is assumed to have a zero mean and is normally distributed. The propagation of each of these uncertainties in an updating damage-identification algorithm is then studied, based on the response-sensitivity approach. A three-dimensional, five-bay, steel-frame structure with local damage in two members is studied for illustration. The mean and standard deviations of the local stiffness parameters identified compare favorably with those from the Monte Carlo technique. The probability density function of the identified local stiffness parameters in both the intact and perturbed states is compared in a subsequent reliability assessment.