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

Document Type : Research Article


1 Maritime Engineering, Amirkabir University of Technology

2 Faculty Member Amirkabir University of Technology

3 Department of maritime Engineering, Amirkabir University of Technology

4 National Iranian Oil engineering and construction Islamic Azad University-Tehran Jonoob branch


In this paper, the performance of a damage detection method based on power spectral density (PSD) is numerically investigated on the dolphin platform of a wharf used for the unloading of merchant ships. In this numerical investigation 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 realise 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.


Main Subjects

[1]  J.K. Vandiver, Detection of structural failure on fixed plat- forms by measurement of dynamic response, in: Offshore Tech- nology Conference, Offshore Technology Conference, 1975.
[2]  O. Salawu, Detection of structural damage through changes in frequency: a review, Engineering structures, 19(9) (1997) 718- 723.
[3]  H. Li, J. Wang, S.-L.J. Hu, Using incomplete modal data for damage detection in offshore jacket structures, Ocean Engineer- ing, 35(17) (2008) 1793-1799.
[4] B. Asgarian, M. Amiri, A. Ghafooripour, Damage detection in jacket type offshore platforms using modal strain energy, Struc- tural Engineering and Mechanics, 33(3) (2009) 325-337.
[5]  F. Liu, H. Li, W. Li, B. Wang, Experimental study of im- proved modal strain energy method for damage localisation in jacket-type offshore wind turbines, Renewable Energy, 72 (2014) 174-181.72 (2014) 174-181.
[6] G. Liu, Y. Zhai, D. Leng, X. Tian, W. Mu, Research on struc- tural damage detection of offshore platforms based on grouping modal strain energy, Ocean Engineering, 140 (2017) 43-49.
[7]  A.A. Elshafey, M.R. Haddara, H. Marzouk, Damage detec- tion in offshore structures using neural networks, Marine Struc- tures, 23(1) (2010) 131-145.
[8]  B. Asgarian, V. Aghaeidoost, H.R. Shokrgozar, Damage de- tection of jacket type offshore platforms using rate of signal ener- gy using wavelet packet transform, Marine Structures, 45 (2016) 1-21.
[9]  M. Pedram, A. Esfandiari, M.R. Khedmati, Finite element model updating using strainā€based power spectral density for damage detection, Structural Control and Health Monitoring, (2016).
[10]  M. Pedram, A. Esfandiari, M.R. Khedmati, Damage detec- tion by a FE model updating method using power spectral den- sity: Numerical and experimental investigation, Journal of Sound and Vibration, 397 (2017) 51-76.
[11]   H. Malekzehtab, A. Golafshani, Damage detection in an offshore jacket platform using genetic algorithm based finite ele- ment model updating with noisy modal data, Procedia Engineer- ing, 54 (2013) 480-490.
[12]  J.F. Wilson, Dynamics of offshore structures, John Wiley & Sons, 2003.
[13]  Regulation, Management and planning organization of Iran, Port and Offshore structures design regualtion (structure and berthing facility), (In persian), (1385).
[14]   D. Adams, Health monitoring of structural materials and components: methods with applications, John Wiley & Sons, 2007.
[15]  A. Esfandiari, F. Bakhtiari-Nejad, A. Rahai, M. Sanayei, Structural model updating using frequency response function and quasi-linear sensitivity equation, Journal of sound and vibration, 326(3) (2009) 557-573.