Uncertainty modelling and assessment of shear resistance in reinforced concrete beams without shear reinforcement

In structural concrete, diagonal tension failure is a significant mode of shear failure in slender flexural members. As a result, an accurate estimate of the slender beam's resistance to shear is required. This study presents a statistical characterisation of the uncertainty associated with various resistance predictive models for slender stirrupless beams with a distinct mode of failure (diagonal tension failure). The investigated models include code- and literature-based shear models. Through a comparative analysis of statistical moments and probabilistic representative models of the uncertainty factor using a substantial number of test cases, the study found that the mechanical model proposed by Tran (2020) demonstrated the best consistency in predicting shear strength. It exhibited a mean of 1.02, standard deviation of 0.16, and coefficient of variation of 16%. To effectively manage the uncertainties identified in the EC2 and AS3600-18 shear models, model uncertainty partial and reduction factors following the EN1990 guidelines were proposed for design practices. However, concerns remain regarding the performance of other shear models, necessitating further reliability investigation.