Assessment of the Reliability Level of the Shear Design Provisions for Members Without Shear Reinforcement

Design standards consist typically of simple closed-form formulations, developed to cover a large variety of cases for load capacity assessments. When establishing such closed-form expressions, a reliability level assessment is vital to ensure that the reliability level complies with the target reliability level. This paper assesses the reliability level of the shear design formulations in the current EN 1992-1-1 and the coming update prEN 1992-1-1 for members without shear reinforcement. Initially, a generic beam example is considered, designed using the partial factors according to the two generations of EN 1992-1-1. Based on the background documents of the two formulations a probabilistic model is established, and the failure probability is assessed and compared with the target reliability level. The failure probability is shown to be less than the target reliability level. Finally, the influence of how to define the characteristic value of the model uncertainty in the shear design models on the reliability level is studied, for both generations of EN 1992-1-1. A 5%-fractile for the characteristic value is established by analysis of a large shear database of shear tests of slender RC beams without shear reinforcement, following the approach described in prEN 1990.