Chapter 15. A Probabilistic Structural Reliability Assessment of Existing North Sea Platforms Available to Purchase

There are four key areas in the SRA of fixed jackets that have been impacted by recent advances in our understanding of extreme offshore wave conditions. These are: the probability distribution of crest heights in extreme seas; the occurrence of breaking waves and their associated enhanced near-surface kinematics; the calculation of wave-in-deck loading where inundation occurs; and, the probabilistic incorporation of multiple structural failure modes. The authors have applied the new approaches for platforms in the Central and Northern North Sea to assess the impact on the estimated structural reliability. The paper describes the experience of using the new methods on one of these platforms in terms of: the sensitivities of the approach to various assumptions; the simplifying assumptions that were used to make the problem more tractable; the computational complexity associated with adopting the full probabilistic approach that is inherent within the new methods; and, the overall impact of using the methods on the calculated structural reliability.