Identification of structural dynamic properties using wavelet transform

The estimation of structure modal parameters from its dynamical response is one of the key issues for vibration based structural health monitoring. In this study, this issue is addressed using a novel signal-processing tool, the wavelet transform (WT). The WT of a time-domain signal is a time-scale distribution obtained by dilating and translating of a chosen mother wavelet. While the dilation of the mother wavelet can be considered as a frequency filtering process, the translation along the time axis can preserve the time dependency of the signal. As a result, the WT is a promising tool for capturing both stationary and transient information from the original measurement. Using the Morlet wavelet, it is illustrated that structural modal parameters can be estimated by the modulus and phase of the WT. The applicability of this WT-based method is validated using some impact responses of a reinforced concrete beam. The results show that the WT can provide quite accurate estimation of the structural dynamic properties.