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 200×300 mm (8×12 in.) and six 300×200 mm (12×8 in.) concrete beams were, respectively, made with and without basalt FRP shear reinforcements. The flexural reinforcement ratios (ρf) ranged from 2.69 to 14.8 times the balanced ratio (ρfb) 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.