System reliability analysis of a ship deck structure for buckling collapse and corrosion limit states

摘要

A system reliability analysis of a ship deck structure for buckling collapse and corrosion limit states is presented. The deck structure is modelled as a structural system of plate elements subjected to the uniaxial compressive loads induced by the hull girder vertical bending moments in sagging. The buckling collapse strength of the plate elements is described by a semi-empirical design formulation. The system strength and load components are modelled as time-variant functions due to the effect of the generalised corrosion on the reduction of thickness and hull girder cross-section modulus over time. The generalised corrosion on the deck structure is modelled as a random process of correlated uniform thickness reductions described by a nonlinear time-dependent model. The corrosion limit states are defined based on a renewal criterion for general corrosion in plate elements. The time-variant system failure probabilities are computed through Monte Carlo simulation. It is shown that the probability of occurrence of a local failure of the ship deck structural system increases significantly over time. The effect of the correlation length of the random process of corrosion on the system failure probability predictions is analysed.