Reliability assessment of a steel plate subjected to distributed and localized corrosion wastage

The objective of this work is to evaluate the reliability of a rectangular steel plate subjected to compressive load and nonlinear time variant non-uniform corrosion wastage. Based on the analysis of the ultimate strength of a rectangular plate with surfaces locally nonuniformly deteriorated by different degrees of random corrosion as a function of time, FORM techniques are applied to assess the structural reliability accounting for the global ship hull structural deterioration. The strength failure events, due to corrosion degradation, are defined by two possible formulations. Either the plate is subjected to random non-uniform distributed type of corrosion wastage that is formed by non-uniform prismatic pits or the plate is subjected to a more severe type of degradation that is developed as random non-uniform localized corrosion wastage, which forms peats likes a hemisphere. Two different correlated failure events are evaluated as a series system defined based on the Classification Society Rules wastage allowance and ultimate strength estimated for the two corrosion wastage models.