Wind and Wave Environments that Lead to Extreme Loads on Offshore Structures

Large wind gusts and rare wave groups create design issues that wind turbines must overcome. These design level gusts and waves generate bending moments on the tower which may lead to failure, or at least accelerated failure. The loads on the wind turbines that lead to failure are not necessarily the result of an extreme gust or a design wave, but may be from a rare combination of the two that leads to an extreme response. To investigate the relationship between wind and wave loading, the stochastic gaussianization iteration method was used in conjunction with the Design Loads Generator to investgate extreme values of the tower base bending moment of a reference floating wind turbine. The response was investigated under three different conditions: Monte Carlo simulations; the Design Loads Generator with a gaussian mask; and the stochastic gaussianization iteration method using the Design Loads Generator to estimate extremes from waves. It was determined that the stochastic gaussianization iteration method with the DLG to maximize the bending moment due to waves resulted in the largest predicted bending moments in a given exposure period.