Barrier failure dominance in time variant reliability analysis

Abstract

In this paper, an important feature of time variant reliability problems is identified. The concept of barrier failure dominance (BFD) is introduced to characterize those problems where an out-crossing or overload failure is more likely to be caused by a very small realization of the barrier (resistance) than by an exceptionally large realization of the load process. This result arises from a study of the ensemble out-crossing rate approximation, reported in a previous paper and which is reviewed herein. It is shown how the notion of BFD can be used to understand the limits of application of the ensemble out-crossing rate approximation. It is also suggested that the acknowledgement of BFD can support the choice of the appropriate simplified solution method for particular problems. A three-dimensional load combination and a resistance degradation problem are studied as examples. The ensemble up-crossing rate approximation is compared with load process-based approximations, using the time-integrated approach, the load combination rule of Turkstra and the point-crossing formula.