Experimental investigation of shear response for steel fiber reinforced lightweight concrete slender beams without stirrups

Previous studies revealed that the shear response and failure mode of lightweight concrete beams without shear reinforcement is brittle. In this study, hooked-end steel fibers (SF) were introduced to enhance shear resistance in steel fiber reinforced lightweight concrete beams without stirrups (SFRLC-BWS). Six structural SFRLC-BWS specimens were designed and constructed to investigate the behavior of shear-critical SFRLC-BWS members. These specimens featured longitudinal reinforcement but without stirrups, utilizing varied mixes with a 0.5% fiber content by volume selected from the material-scale testing phase. Specimens ranged in beam depth from 300 to 900 mm, maintaining a constant shear span-to-effective depth ratio of 3.5 and with 1% and 1.5% longitudinal reinforcement ratios. The test results indicated that the normalized shear stress at failure decreased with increasing specimen total depth, suggesting a size effect for SFRLC-BWS specimens. However, the addition of SF into the concrete matrix significantly augmented shear capacity compared to predictions by American Concrete Institute (ACI) 318-19 for RC members without SF. This study found that replacing the minimum shear reinforcement with 0.5% steel fiber volume was effective in satisfying shear reinforcement requirements and enhancing the shear strength capacity of SFRLC-BWS.