The effect of marine growth dynamics in offshore wind turbine support structures

Offshore Wind Turbine (OWT) support structures are invariably subject to colonisation by marine organisms, which are not spatially or temporally linear. Marine Growth (MG) varies based on location and season, and with structural and material characteristics. MG is a major consideration for engineers. As organisms settle on the structure they may increase surface roughness and cross-sectional area, altering drag and inertia coefficients and increasing hydrodynamic loading. Furthermore, the added mass from MG also influences structural integrity. As such, there is considerable uncertainty surrounding the response of OWTs to MG, as this phenomenon is often overlooked in FEA modelling. This paper uses the parametric FEA model of an OWT support structure developed in (Martinez-Luengo, Kolios, and Wang 2017) to analyse how different growth rates and patterns of zonation of MG affect the structural integrity of the system. MG has a great impact in the fatigue life of the structure, as a reduction of 58.6-59.2% is presented in the baseline scenarios