On the ergodicity assumption in Performance-Based engineering

In the Performance-Based Engineering (PBE) framework, uncertainties in system parameters, or modelling uncertainties, have been shown to significant effects on capacity fragilities and annual collapse rates of buildings. Yet, since are non-ergodic variables, their consideration failure rate calculations offends Poisson assumption independent crossings. This problem has addressed literature, errors found negligible for small rates. However, could be serviceability limit states, when integrated time, provide lifetime probabilities. Herein, we present a novel formulation fully avoid error integration variables. The proposed product-of-lognormals is compatible with popular fragility approaches PBE context. Moreover, address states realistic reinforced concrete buildings, find order 5 8% 50-year lifetimes, up 14% 100 years. Computation accurate probabilities context clearly important, as it allows comparison target reliability values other structural analysis formulations.