A DAMAGE IDENTIFICATION METHOD BASED ON STRAIN MODAL RESPONSE RECONSTRUCTION

Damage identification technology of civil structures is of great significance to improve the reliability and safety of structures, and it is a hot topic in the research of civil structural health monitoring. Current damage identification methods often need to identify the modal parameters or accurately obtain the external load information of a structure, which greatly limits their application in practical engineering. To overcome the limitations of the existing methods, the structural dynamic response reconstruction method is introduced into the damage identification and a damage identification method based on strain modal response reconstruction is proposed. The finite element model of the healthy structure is constructed, and the measurement signal is input from the damaged structure. The global modal response of the structure using the undamaged model could be obtained through the strain reconstruction method based on empirical mode decomposition. The discrepancy between the modal response collected by sensors and the reconstructed modal response was taken as the basis of finite element model modification, and the damage location and damage degree were obtained through iterative calculation of the sensitivity matrix of the transmissibility constructed by the strain mode ratio. This method does not need to obtain the external excitation information of the structure, and can realize the accurate identification of structural damage with a few measurement signals through the efficient time-domain strain reconstruction. To verify the accuracy and efficiency of this method, single damage and multiple damage identifications of a continuous beam were carried out. The influence of measurement noise and modal order selection on the identification results was discussed. The results show that this method can accurately and efficiently identify the damage of different degrees, and has strong robustness against measurement noise.