Interval assessments in structural reliability using the imprecise Dirichlet model

A new approach to structural reliability analysis under incomplete information about the stress and strength in the form of intervals provided by experts or obtained as a result of imprecise measurements is proposed in the paper. The approach takes into account the possible fact that the number of judgments or observations may be rather small. It is shown that interval-valued information about the stress and strength can be modelled by means of a set of Walley’s imprecise Dirichlet models. Very simple expressions for computing bounds for the structural reliability and unreliability are obtained in the paper under conditions of independence and lack of knowledge about independence of the stress and strength. Numerical examples illustrate some advantages of the proposed approach.