Joint Probabilistic Description for Combined Seas

Abstract

An extension of joint omnidirectional probabilistic model including combined seas and possibility of environmental parameters approaching from different direction is presented. The following parameters are considered: mean wind speed, wind direction, significant wave height (sea and swell), spectral peak period (sea and swell), wind sea direction, swell direction, current speed and current direction. Two approaches for wind sea and swell modelling are proposed. The joint description is developed for three locations at the Norwegian Continental Shelf and for the West Shetland. Uncertainties related to it are discussed. The model is meant to be applied in reliability analysis of offshore structures, in particularly FPSO units, for which a proper account of directional effects and combined seas is important.