Jacket design to resist ship impact

The response of three jacket structures is investigated under accidental ship impact. Fully non-linear finite element analysis results agree well with the predictions of a locally non-linear beam–column model attached to an elastic structure. The results suggest that typical North Sea jackets in moderate water depth and carrying moderately large topsides may be able to resist very high impact energies. For very light jackets, however, sudden overall collapse is possible, particularly under nodal impact. The criticality of ship impact for jacket design is very dependent on the relative magnitudes of the loads at which the ship and the jacket collapse. The topside configuration is also important as it determines the manner in which tension loads generated during the impact are redistributed through the structure.