Recursive Hilbert-Huang Transform Method for Time-Varying Property Identification of Linear Shear-Type Buildings under Base Excitations

Abstract

This paper presents a recursive Hilbert-Huang transform method for the time-varying property identification of shear-type buildings under base excitations. To overcome nonorthogonality and modal perturbation issues, all significant intrinsic mode functions of each signal and their Hilbert transforms were summed to track any variation of structural parameters of a multistory building over time. Given floor masses, both the stiffness and damping coefficients of the building were identified one by one from the top to bottom story. The overall accuracy of the identified parameters was measured by an index of accuracy based on the weighted root-mean-squared evaluation proposed in this study. One- and two-story shear buildings with abruptly, gradually, and periodically varying parameters were used as examples. The numerical results indicated that the proposed method is efficient, robust, and accurate in tracking variations of the properties of multistory buildings. Finally, the proposed method was applied into the identification of the time-varying natural frequency of a real-world high-voltage switch structure due to the friction mechanism used in the switch. The range of the identified frequency by the proposed method was in good agreement with that attained by the conventional least-squares method.