Fatigue reliability of mooring chains, including mean load and corrosion effects

Abstract

A reliability formulation for mooring chain fatigue is developed based on the S–N approach. The effects of mean load and degradation due to corrosion are included by starting from a S-N model with parameterized dependence to the mean load and a customized corrosion condition scale. Partial dependence between the failure events of individual links within a chain segment is addressed by distinguishing between properties and loads that are assumed to be either independent or fully correlated between links. The paper includes a thorough case study, based on a realistic case. A global sensitivity analysis is presented, to assess the importance of interaction between random variables and to justify a reduction of the model dimension. A reliability analysis is then performed, and the effect on failure probability from variation of a range of parameters and model assumptions is studied.