Damage detection in dolphin platform of a wharf by finite element model updating

The coastal structures such as wharves withstand severe operational conditions during their service life; hence, they are susceptible to damage and reduction in the stiffness of their elements. In this paper, the performance of a damage detection method based on power spectral density is numerically investigated on the dolphin platform of the oil wharf used for the unloading of crude oil to the refinery. This investigation is held numerically, and the damage is modeled as a percent reduction in stiffness of the elements. For this purpose, the finite-element model of the dolphin is made in the MATLAB software and the effect of surrounding water is considered as the added mass on the elements. To probe the performance of the method on the dolphin model, several assumed damage scenarios with different levels of damage in the structure, are considered. Furthermore, an approach for calculation of the spectral density of excitation using an approximate FRF is introduced. Results prove the success of the method in the identification of the parameters of a stiff coastal structure like a dolphin. Besides, the results from these investigations prove that the added mass significantly affects the damage detection results. The quality and accuracy of the numerical results prove the merits of damage detection by finite-element model updating in the frequency domain. The results of the present study urge the practical assessment of the performance of the method in the future.