FORM and Out-Crossing Combined Time-Variant Reliability Analysis Method for Ship Structures

In view of the varying characteristics of material properties, environmental conditions, and loading effects randomly with long time, the random and temporal characters of different variables should take into account when the structural reliability analysis methods are adopted to estimate the reliability of ship structures. Therefore, a time-variant reliability analysis method combined the out-crossing approach and the first-order reliability method is proposed. In this paper, the research is conducted on the time-variant feature of ship structures under the corrosive action according to the environmental testing data. Furthermore, the limit state function is derived based on the time-variant feature analysis results in which the strength and stress of ship structures are both regarded as variables with respect to time. Then, the time-dependent reliability model of ship structures is established based on this combined method, and the solving process of parameters in this model is illustrated. Finally, a case of a ship grillage structure under marine environment is given to prove that the proposed method has a good application in evaluating the reliability of ship structures. The comparison analysis using different methods is also conducted to study the accuracy and efficiency of this method.