Shear behavior of fiber-reinforced lightweight concrete beams reinforced with BFRP bars

This paper presents an experimental investigation on the shear performance of fiber-reinforced lightweight concrete (FRLWC) beams reinforced with basalt fibers reinforced polymer (BFRP) bars. Ten beams 150x250x2400 mm were tested under four-point loading configuration until failure. The investigated parameters included the concrete type (steel fiber-reinforced lightweight concrete (SFRLWC), basalt fiber-reinforced lightweight concrete (BFRLWC), and polypropylene fiber-reinforced lightweight concrete (PFRLWC)), the fibers’ volume fraction (0, 0.5, and 1.0 %), and the beams’ longitudinal reinforcement ratios (0.95 and 1.37 %). The test results demonstrated that beams cast with SFRLWC containing 0.5 % steel fibers achieved shear capacities 23 % and 16 % higher than those cast with BFRLWC and PFRLWC, respectively. Similarly, beams cast with SFRLWC containing 1 % steel fibers showed greater increase in shear capacity, with gains of 47 % and 41 % compared to BFRLWC and PFRLWC, respectively. BFRLWC beams demonstrated intermediate performance between SFRLWC and PFRLWC beams, with reduced crack width than PFRLWC beams. Increasing the reinforcement ratio from 0.95 % to 1.37 % showed a shear capacity increase of 16 % for beams cast with BFRLWC. A new model was proposed to predict the shear capacities of FRWLC beams reinforced with BFRP longitudinal bars. The proposed model accurately predicted the shear capacities of BFRLWC beams with predicted-to-experimental ratio of 1.01 (standard deviation, SD = 0.05). It also predicted the shear capacities of PFRLWC and SFRLWC beams with V pred /V exp = 0.99 (SD = 0.06) and 0.90 (SD = 0), respectively. • Using basalt fibers resulted in enhanced shear capacity of the tested beams. • Basalt fibers showed intermediate performance between steel and polypropylene fibers. • Existing models fail to predict the shear capacity of FRP-reinforced beams cast with LWC. • A new model is proposed to predict the shear capacity of the beams.