Analysis and Design of Offshore Jacket Wind Turbine

Offshore wind is an attractive source of renewable energy. In order to harvest this abundant energy source wind turbine farms are needed. In order to extend the application of offshore fixed wind turbine (OFWT) in deep water where winds are stronger and steadier, there are research works on fixed wind turbine which is ongoing on larger water depth like 70-100m. The focus in this thesis is analyses to support design of OFWT jacket substructure piled to the seabed, with a particular focus the modeling and ultimate capacity behavior of such facilities subjected to extreme wind and wave forces. During modelling, Genie and USFOS are applied to re-design and modify the finite element model of wind turbine substructure given by Aker Solutions. New design jacket substructures are both for the intermediate water depth 70 meters and 100 meters with the soil and pile modelling based on the Ekofisk data. Based on design load case, both of the static pushover analysis and API design code check is performed on the jacket substructure model to check the ultimate capacity. The pushover analysis is performed through nonlinear finite elemnt code USFOS. The API code check is based on hand calculation.The response of the jacket substructures under design load case is most interested in, which could indicate the critical position on jacekt, furthermore the effect of the direction and size of the wind and wave load. Meanwhile, through comaprission of results, the two methods could confirm each other, which could help to get the deeper understanding of ULS of offshore jacket structure