A FORMAL GEOMETRICAL MODELLING OF WAVE ACTIONS FOR STRUCTURAL RELIABILITY

The actual challenge for the requalification of existing offshore structures through a rational process of reassessment leads to state the importance of Response Surface Methodology. At different steps along the quantitative analysis, quite a lot of approximations are performed as a surrogate for the original model in subsequent uncertainty and sensitivity studies. The authors propose a geometrical description of the n{sup th} order Stokes model in the form of a random linear combination of deterministic vectors. These vectors are obtained by rotation transformations of the wave directional vector. This allows to discuss the complexity level to be introduced in stochastic modeling of the wave actions, within its relevance for the probabilistic mechanics analysis of offshore structures. In situ measurements are used to perform ranges and distributions of basic variables. A striking feature is that the environmental actions are site specific.