Applicability of FFS Assessment Using Partial Safety Factors Evaluated by Infinite Plate

This paper investigates the applicability of a Fitness-For-Service (FFS) assessment of crack-like flaws using the Partial Safety Factors (PSFs) calculated from the infinite plate model. Procedures of FFS assessment using PSFs are provided in API579-1, and several PSFs calculated from an infinite plate are given to evaluate structures approximately for simplification. However, the applicability of these PSFs is not clear, and the safety margin cannot be evaluated precisely. To clarify the applicable region of these infinite plate PSFs in this paper, we calculate PSFs of various structures, crack geometries and load types and compare with those of the infinite plate. We also examine whether the target reliability is satisfied when infinite plate PSFs are applied to the concrete structures. In addition, we used sensitivity analysis to show the dependence of probabilistic properties on the safety margin. Both the limit state function method and the Monte Carlo simulation method are used for the analysis, and the limit state is defined by the Failure Assessment Diagram (FAD) curve. Finally, the relation between infinite plate PSFs’ applicability and probabilistic properties of structure, and crack geometries are discussed.