Improving the performance of the autoregressive method in modal identification of output-only systems using the empirical mode decomposition

Abstract

The autoregressive method is one of the simple methods for modal identification of the output-only systems. However, through the autoregressive method, for identifying n modes at least n sensors are required which is considered as the main challenging issue of this method. Also, in order to extract acceptable modal parameters using this method it is required to implement stationary response.To overcome these issues, in this study, the empirical mode decomposition is adopted to improve the performance of an autoregressive method for extraction of frequencies and damping ratios of a structure from stationary or non-stationary response. To evaluate the efficiency of the new developed method, two building structures and support tower for a segmental bridge are considered and the frequencies and damping ratios are obtained using developed method.The results indicated that the proposed method adequately estimates the considered parameters using stationary and non-stationary response which recorded by only one sensor. Moreover, it is proved that this method outperforms in comparison with the other relevant methods which applicable with the non-stationary responses.