Comparison of uncertainty models in reliability analysis of offshore structures under marine corrosion

Reliability analysis of existing offshore structures in seawater conditions requires realistic models for corrosion. In this paper, a probabilistic model for marine corrosion is adopted. Due to scarce and imprecise information, the model parameters cannot be specified precisely and are merely known in form of bounds. To deal with this issue, selected uncertainty models are applied, and their features are compared. The investigation includes pure probabilistics, interval modeling, fuzzy methods, and imprecise probabilities. The models are applied to find an upper bound for the failure probability. The results are compared in view of information content and numerical efficiency. For the comparative study a simple plate structure is used, for which reference results are available. Then, the investigation is extended to a fixed offshore platform.