Improved structural damage detection method based on the natural frequency vectors

According to the change of natural frequencies of damaged structure versus intact structure, a novel concept of natural frequency vector and hence the natural frequency vector assurance criterion (NFVAC) has been proposed and used as damage indicator to determine the damage state of the structure. But the NFVAC only uses messages of the correlation between two natural frequency vectors. Herein a new damage indicator is presented. In this indicator, the average error of the elements in the two vectors is also considered as an impact factor, so the improved indicator is the combination of the average error and NFVAC of two natural frequency vectors. In order to verify the feasibility and validity of the proposed method in the damage detection for engineering structure, an 8-story shear frame is adopted for damage detection demonstration. The finite element model of the frame is built to simulate the damage feature database, and then the proposed new damage indicator is used in damage detection tests of the model and the results are compared with these obtained by using NFVAC. It is found that the improved damage detection method based on the new damage indicators is more effective in damage detection for engineering structures.