Abstract
Scour risk assessment considering reaction force at foundation was proposed and applied to newly developed pentapod suction bucket support structures for a 5.5 MW offshore wind turbine under ultimate limit state environmental load. Scour hazard was obtained according to scour depth by using an empirical formula, which is the function of marine environmental conditions such as significant wave height, significant period, and current velocity. Fragility of the pentapod support structure was evaluated using the bearing capacity limit state criterion under ultimate limit state load case. Scour risk was assessed by combining the scour hazard and the fragility. Finally, scour risk of the developed pentapod suction bucket support structure under ultimate limit state has been assessed.