Sensitivity and uncertainty studies for the modelling of marine growth effect on offshore structures loading

Franck Schoefs (1)

1 GeM - Institut de Recherche en Génie Civil et Mécanique

Structural response to extreme events or fatigue loadings and structural integrity are major criteria to be quantified in a rational process of reassessment. It is now well established that the probabilistic mechanics approach gives an efficient means for measuring the relative changing in safety level compared to a predefined requirement. To this aim, effects of marine growth have been largely studied during the last two decades. This natural process of structural colonization is particularly hard to embrace because it leads to various consequences as over-loading effect coming from screen and drag effects, bio-chemical attacks of materials and mask effects for inspections methods. Only effects on loading are studied here. These effects are particularly hard to quantify because of the bio-variety of marine growth, season conditioning, natural cleaning or death of species, severe competition leading to replacement of some species and of course local hydrodynamic conditions. As in situ data collection through inspections is hard to practice and very expensive, lot of works propose experiments respecting scale effects and numerical modelling. Both are needed to perform uncertainty and sensitivity analyses. This paper proposes a numerical analysis of marine growth effects based on Response Surface Methodology. This method is here suggested to provide explicit approximations of load variables acting on offshore structures submitted to extreme events or fatigue loading as Jacket platforms. Then, from a sensitivity analysis, main factors conditioning load effects are pointed out. From a physical analysis of hydrodynamics parameters affecting these dominant variables, their probabilistic modelling is then suggested using available published experiments for several probabilistic characteristics.

Domaines: Mécanique [physics.med-ph]; Matériaux

Franck Schoefs. Sensitivity and uncertainty studies for the modelling of marine growth effect on offshore structures loading. ASME 2002 21st International Conference on Offshore Mechanics and Arctic Engineering (OMAE'02), 2002, Oslo, Norway. pp.275-281, ⟨10.1115/OMAE2002-28385⟩. ⟨hal-01008881⟩