Shear performance of basalt fiber-reinforced concrete beams reinforced with BFRP bars

Abstract

This paper reports on the experimental and analytical investigation of the shear performance of concrete beams cast with basalt fiber-reinforced concrete (BFRC) and longitudinally reinforced with basalt fiber-reinforced polymer (BFRP) bars. Fourteen hybrid (BFRC-BFRP) beams with no stirrups were tested to failure under a four-point loading setup. The investigated parameters included the volume fraction, Vf, of the added fibers (0.75 and 1.5%), the reinforcement ratio of the BFRP bars,ρ, (0.31, 0.48, 0.69, 1.05, and 1.52%), and the shear span-to-depth ratios, a/d, of the beams (3.3 and 2.5 for slender and short beams, respectively). The tests results showed that adding 0.75% of basalt macrofibres (BMF) improved the shear capacity of the slender and short beams by 46 and 43 %, respectively, compared to 81 and 82% when 1.5% of BMF were added. The impact of adding the BMF on the shear strength of the beams diminished as the longitudinal reinforcement ratios increased. The existing models overestimated the shear strength of the tested beams with an average predicted-to-experimental ratio ranging between 1.15 ± 0.03 and 2.48 ± 0.29. A shear model that accounts for the type of the longitudinal reinforcement and the added fibers was proposed to predict the shear strength of the BFRC-BFRP beams. A good agreement between the predicted and experimental shear strength was evident with a predicted-to-experimental ratio that ranged between 0.98 ± 0.11 and 0.88 ± 0.02 for the slender and short beams, respectively.