A Discussion on the Reliability of prEN1992-1-1:2021 Shear Strength Provisions for Fibre Reinforced Concrete Members Without Shear Reinforcement

The Eurocode 2 for the design of concrete structures (EN1992-1-1:2004) is undergoing a revision that will lead to the publication of the second generation of this code to be used across all CEN member countries. Therefore, the impact of the code will reach hundreds of millions of people. Importantly, the Eurocode 2-revision will incorporate many significant changes, amongst which is the introduction of design provisions for fibre reinforced concrete (FRC). In this regard, one of the most important aspects for ultimate limit state (ULS) design will be the consideration of the shear strength of FRC members without shear reinforcement. Such a failure mode is associated with a number of uncertainties, as well as with a potentially-brittle failure response. However, so far, the design models proposed in the Eurocode 2-revision have not been accompanied by a robust reliability-based calibration of the FRC partial factor γ_SF. Within this context, this paper presents the results of an investigation on the safety format and the partial factor γ_SF for FRC members without shear reinforcement currently provisioned in the draft for the new Eurocode 2 (prEN1992-1-1:2021). Firstly, a database of experimental results on FRC beams is used to determine the model error. On that basis, a probabilistic analysis is performed using the First Order Reliability Method (FORM) to determine adequate values of γ_SF for varying target reliability indices. The results of the study show how γ_SF values need to updated in order to reach reliability indices typically considered for ULS design.