Application of Semi-probabilistic Methods to Verification of Series System

Abstract

Non-linear finite element analysis (NLFEA) has become a widely used tool in the reliability verification of reinforced concrete (RC) structures. Reliability assessment of RC structures is a challenging task and simplified approaches to reliability verifications are needed to allow for routine applications. Simplified semi-probabilistic methods such as the partial factor method (PFM) or the Method of Estimation of Coefficient of Variation (ECoV) may yield over- or under-conservative approximations. This contribution investigates such errors related to the applications of these two methods to series systems; the design resistances obtained by the probabilistic approach are considered as a reference level. It appears that PFM provides good approximations as the method is focused on critical members in the cases under consideration. ECoV may overestimate up to 20% in situations where NLFEA based on mean and/ or characteristic values fails to identify a dominating failure mode. The maximum observed error is attributed mainly to the failure in identifying the type of distribution of the system resistance. The presented limited analysis indicates several directions for further research (analysis of other types of structural systems, cases with non-lognormal resistances, effects of a number of system components, and their mutual correlations, and performance of advanced methods for reliability verification). Recommendations on how to identify situations when a significant error can be expected should be provided for practical applications of simplified semi-probabilistic methods.