2009 Modal identification of ambient vibration structure using frequency domain decomposition and wavelet transform

Frequency domain decomposition (FDD) has been widely used for output-only system identification due to ambient excitations in the frequency domain. FDD, however, usually requires a prior knowledge on natural frequencies, and also has troublesome in modal damping ratio identification as well as its strict hypothesis on uncorrelated white noise excitation and lightly-damped structures. Recently, wavelet transform (WT) has been developed most recently for the output-only system identifications in the time-frequency plane, especially its unique advantages on dealing with non-stationary, transient and non-linear inputs and outputs as well as dynamic system information in both time and frequency domains. This paper aims to present FDD and WT used for the output-only system identification of the ambient vibration structures. Modal parameters will be estimated from full-scale ambient vibration measurements of 5-storey steel structure