Shear Behavior of Basalt Fiber Reinforced Concrete Beams with and without Basalt FRP Stirrups

This paper examines the shear strength and behavior of concrete beams reinforced with basalt fiber-reinforced polymer (basalt FRP) bars with and without shear reinforcements. Six $200\times 300\mathrm{mm}$ ($8\times 12\mathrm{in.}$) and six $300\times 200\mathrm{mm}$ ($12\times 8\mathrm{in.}$) concrete beams were, respectively, made with and without basalt FRP shear reinforcements. The flexural reinforcement ratios (${\rho }_f$) ranged from 2.69 to 14.8 times the balanced ratio (${\rho }_{fb}$) for nonshear reinforced (NSR) beams and 1.69 to 6.88 for the shear reinforced (SR) concrete beams. Two different shear span-to-depth ($a/d$) ratios were considered for the NSR-beams (5.65 and 7.0) and three different $a/d$ for the SR-beams (1.5, 2.5, and 3.5). The test results are presented in terms of crack patterns, failure modes, load-deflection, load-strain behavior, and shear capacity. It was observed that for both SR- and NSR-beams, the shear capacity increased when the area of basalt FRP reinforcement increased for the same span to depth ratio ($a/d$), whereas the shear capacity decreased when the span to depth ratio ($a/d$) increased. In light of the experimental results, prediction models and design code equations were evaluated to test their accuracy in predicting the shear strength of basalt FRP RC-beams. Standard provisions predictions were both conservative and nonconservative. The predictions based on the modified compression field theory for the nonshear reinforced beams were the closest to the experimental.