Possibilistic safety assessment of structures under hybrid uncertainty

The probabilistic and possibilistic methods of reliability analysis of structures have been developed independently. However, the designers will prefer the flexibility of modeling the structural parameter uncertainty either probabilistically or possibilistically depending on the nature and quality of the available data. Thereby, the complex structural model will involve both types of uncertain parameters and can be referred as hybrid uncertain system. The present paper deals with the safety evaluation of such hybrid uncertain system in possibilistic format. The limit state functions involving both the random and fuzzy variables need to express in terms of the fuzzy variables. This necessitates transformation of random variables to equivalent fuzzy variables satisfying the consistency condition. In present study, the entropy based transformation theory of expressing the uncertainty information applied in various fields of engineering, is used. The possibilistic reliability index and the possibilistic design point are obtained by numerical optimization technique to evaluate the possibility of failure. A numerical example illustrates the capability of the transformation approach to evaluate the safety of the structure under hybrid uncertainties.