Identifying the modal parameters of structure from Seismic Response in time-frequency domain

Abstract

This work presents the use of a short time Fourier transform to determine the natural frequencies, damping ratios, and mode shapes of a structure from its free vibration or earthquake response data. The short time Fourier transform is applied to the measured acceleration responses of a structural system, and to reconstruct the autoregressive with exogenous input (ARX) model in time-frequency domain. The accuracy of this procedure is numerically confirmed; the effects of the length of frequency band and noise on the ability to accurately estimate the dynamic characteristics are also investigated. The feasibility of the present procedure to elucidate real structures is demonstrated through processing the measured responses of steel frames in shaking table tests.