Effect of Shear Span-to-Depth Ratio on Shear Strength of High-Strength Concrete Beams Reinforced with BFRP Bars

An experiment was conducted to investigate the influence of the shear span-to-depth ratio (a/d) on the shear capacity and behavior of high-strength concrete (HSC) beams reinforced with basalt fiber-reinforced polymer (BFRP) bars. Six BFRP reinforced HSC beams, concrete compressive strength\({(f}_{c}^{\prime}\)) equal to 90.67 MPa, were cast and tested in a four-point bending arrangement. The shear span-to-depth ratios ranged from 1.5 to 4. The results indicated that the shear span-to-depth ratio, remarkably, affects the shear capacity and behavior of HSC deep beams reinforced with BFRP bars. Due to the increase in the shear span-to-depth ratio from 1.5 to 2.5, the shear capacity of BFRP-reinforced HSC deep beams decreased by 51.78%; however, an insignificant effect was observed in HSC slender beams reinforced with BFRP bars. Additionally, the applicability of models from different design codes to predict the shear strength of FRP-reinforced concrete beams was investigated. The strut coefficients from ACI 318-19 were modified to predict more accurate results from strut and tie models. The ratio of the experimental to predicted ultimate shear strength of the beams with the modified strut-and-tie model from ACI 318-19 (\({V}_{u,exp}/{V}_{propse } )\) had a mean value of 1.02 and a coefficient of variation (CV) of 15.03%.