Structural damage identification of an offshore platform based on wavelet packet energy rate changing and model updating

Accurate damage identification is an important guarantee for the safe operation of an offshore platform. Considering that the wavelet packet analysis can effectively reveal the features of signals, this paper proposes a scheme selection principle of the wavelet packet decomposition, which is rather sensitive to the damage. The wavelet packet energy change rate of acceleration signals before and after structural damage was taken as the residual，the elastic modulus of the structure was taken as the parameter to be updated，through the sensitivity analysis，a new objective function was constructed for model updating and structural damage identification. Applying the above identification method to a simply supported beam model, it indicates that it can accurately identify the existence, location and degree of damage, which verifies the feasibility of the method. The identification and analysis of the signal polluted by noise show that the method has certain robustness，the signal with serious noise pollution is denoised by wavelet threshold，and the identification effect is improved compared with that before noise reduction. The method has been applied to an offshore jacket platform model, and the damage scenario of different height and different type of members can be identified effectively，indicating that the method is also suitable for multi-storey complex structures. © 2023 Chinese Vibration Engineering Society. All rights reserved.