Hybrid Reliability Analysis — Probabilistic and Non-Probabilistic Methods Combined

Hybrid Reliability Analysis (HRA) quantifies the probability that an engineering system will perform its intended function when uncertain inputs are of two fundamentally different kinds: aleatory uncertainties (natural randomness, modelled with probability distributions) and epistemic uncertainties (lack of knowledge, modelled with intervals or fuzzy sets). By treating both uncertainty types simultaneously rather than collapsing them into a single probabilistic framework, HRA produces more truthful reliability estimates in design, structural, and systems engineering problems.