NUMERICAL MODELLING OF DAMAGE TO RING STIFFENED CYLINDERS.

The problem of damage to the ring stiffened cylindrical legs of offshore platforms, caused by berthing impact of a vessel, is addressed in this paper. The damaged state is characterised by large local deflections and stresses which can cause a significant reduction on the axial strength of the affected platform leg. This knock-down effect can be even more important in the case of shells with slender geometries. Experimental work was performed on the denting of a ring stiffened cylinder the geometry of which is representative of the new generation of floating platforms. The damage process was treated as a static problem by denting the ring-stiffened member thorough a knife edge indentor which was chosen to represent an idealised side edge impact of a ship.