Statistical properties of bulk carrier longitudinal strength

• Statistical properties of bulk carrier longitudinal strength.
• Hull girder section modulus and ultimate bending moment capacity.
• Time-variant corrosion wastage.
• Taylor series expansion method and Monte Carlo simulation.
• Correlation among random variables and applicability of Central Limit Theorem.

The paper focuses on time-variant longitudinal strength of bulk carriers under corrosion wastage, applying both Taylor series expansion method and Monte Carlo simulation. Hull girder section modulus and ultimate bending moment capacity are determined, by classical beam theory and the commonly applied incremental-iterative approach, respectively. Two main aspects are fully discussed and investigated, according to the final recommendations of last ISSC Report. The former regards the covariance between annual corrosion rates of individual structural members, commonly assumed as uncorrelated. Really, as it is conceivable that a certain correlation exists, three different cases are investigated: uncorrelated variables, fully correlated variables, full correlation between structural members belonging to the same category of compartments. The latter investigates the probability density function of both hull girder section modulus and ultimate bending capacity, because the Central Limit Theorem cannot be applied when correlation among random variables exists. Finally, as a test example, the bulk carrier section, presented in the last ISSC benchmark study, is analysed.