Stochastic Analysis of Vertical Wave Loads on Deck

Vertical loads on a platform deck due to incident random waves — long-crested and Gaussian, are studied. Loads on the deck are due to wave-slamming, added-mass over the wetted length and nonlinear Froude-Krylov components. Reliable estimation of these loads and their duration is important in evaluating their effects on platform response (global or local). Emphasis of the present work is to study statistical measures such as expected maximum/minimum impact load and its duration. Gaussian waves are numerically simulated over several points of a two-dimensional deck in time-domain and each deck-wetting event identified and tracked from its inception to expiry. Forces are modeled using a simplified two-dimensional slamming model following Kaplan’s (1987) approach. Use of von Ka´rma´n method, and hence instantaneous wave profile, enables multiple slamming regions to be considered. Simulated results for expected deck-wetting duration and expected maximum wetted length are then compared against analytical results for one- and two-dimensional stationary Gaussian processes.