Probabilistic analysis of nonlinear wave loads on ships using weibull, generalized gamma, and pareto distributions

The statistics of nonlinear wave-induced bending moment in ship hull girders in a shortterm period is studied. Systematic probabilistic analysis is performed directly on wave load time histories for different ship types under various sea state and ship speed conditions. The order statistics concept and peak-over-threshold method are used for estimation of the extreme wave loads. The generalized gamma, generalized Pareto, and Weibull distributions are utilized for describing wave load peak values. The three distributions are evaluated and compared with respect to the shape parameters, goodness of fit of the models to the wave load data, and statistical uncertainty in the extreme estimates. Important features of the wave load statistics are also revealed.