Analyses of Shear Capacity Equations for UHPFRC Beams

This research assesses the capability of existing shear capacity equations to adequately predict the shear strengths/ultimate loads of ultra-high performance fibre reinforced concrete (UHPFRC) beams in order to check their level of accuracy and to determine the equation that can be reliably used to predict/design UHPFRC beams against shear loading. Influential shear variables like shear span-depth ratio (a/d), percentage volume of steel fibre (Vf), longitudinal tensile reinforcement ratio (ρ), compressive strength, stirrup spacing (s), steel fibre topology and steel fibre-UHPFRC matrix bond stress were used to carefully select some shear capacity equations as well as some beams from existing literature for the analyses. Major findings from the analyses revealed that UHPFRC beams’ shear capacity is greatly underestimated by CECS2020 (2020), SIA 2052 (2016), JSCE (2006), Imam et al. (1997), Khuntia et al. (1999), Ashour et al. (1992), Al-Ta’an and Al-Feel (1990), and Narayanan and Darwish (1987). Also, Shear capacity equations developed by Hussein (2015), Aoude et al. (2012), Kwak et al. (2002) and NF P 18-710 (2016) seriously overestimate the shear capacity of UHPFRC beams. Further findings from the analyses showed that Smith and Xu’s (2023) shear capacity equation is capable of perfectly predicting the shear capacity of both UHPFRC beams and UHPFRC beams containing coarse aggregate (UHPFRC-CA) with minimal deviations and over 92% consistent agreement with experimental values. Finally, it is advised that researchers should make use of experimental data to develop new equations for analysing the structural integrity of new materials like UHPFRC members instead of simply modifying existing equations for use in evaluating a new material with different properties.