A wavelet-based approach to identifying structural modal parameters from seismic response and free vibration data

This work presents the use of a discrete wavelet transform to determine the natural frequencies, damping ratios, and mode shapes of a structure from its free vibration or earthquake response data. The wavelet transform with orthonormal wavelets is applied to the measured acceleration responses of a structural system, and to reconstruct the discrete equations of motion in various wavelet subspaces. The accuracy of this procedure is numerically confirmed; the effects of mother wavelet functions 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 and the free vibration responses of a five-span arch bridge with a total length of 440 m.