Risk Based Inspection Planning for Ship Structures Using a Decision Tree Method

A theoretical framework of risk-based inspection and repair was proposed for ship structures subjected to corrosion deterioration. A repair index was presented to consider reliability updating after repair. The reliability updating after inspection and repair was performed by using the Bayesian updating method. A decision tree was established for selecting the optimal inspection and repair strategy for ship structures. By comparing the expected costs associated with different inspection and repair strategies, the smallest expected cost associated with the inspection and repair strategy can be identified as the optimal one. Based on this, a method was proposed to determine the sensitivities of both optimal inspection and repair strategy. Furthermore, some formulae were derived to analyze the sensitivities. A numerical example was investigated to illustrate the process of selecting the optimal inspection and repair strategy. The results show that the decision tree method is very effective. Furthermore, different values of various costs have significant effects on the reliability and stability of decision results.