Substructure damage identification based on sensitivity of Power Spectral Density

Abstract

In this paper, a new method for substructure damage identification under random excitation is proposed, which is based on the sensitivity of the power spectral density (PSD) analysis. The finite element model is divided into different substructures and combined with the improved reduced system (IRS) method to achieve model condensation. When the system is subjected to excitations, the sensitivity of dynamic response of power spectral density function to structural damage parameters is obtained. The substructure is regarded as an independent structure, and the structural damage identification is realized by using the method of model updating. By increasing the number of frequency points used for damage identification to reduce the selection of measuring points. The identified results are obtained by updating the damaged parameters using sensitivity of PSD with few measurement points. The assembled finite element model is obtained by condensation and the number of elements is greatly reduced. The substructure damage identification method based on the PSD sensitivity is proposed in this paper, it not only reduces the size of analytical model involved in model updating but also decreases the uncertain parameters that need updating, thus resulting in a rapid convergence of the iterative process. The numerical and experimental model of a six-story steel frame structure with different damage conditions demonstrates the satisfactory identification results from the proposed method.