Experimental and Numerical Studies on the Shear Strength of HFRC Beams without Stirrups

This study investigates the shear strength performance of reinforced concrete (RC) beams without stirrups cast using hybrid fiber-reinforced concrete (HFRC). Six mixtures were prepared by combining two types of fibers—steel, polypropylene (PP), glass, basalt, and polyvinyl alcohol (PVA)—with volume fractions of 0.25% or 0.5% each. The mechanical properties were evaluated along with the structural behavior of the RC beams focusing on crack development, ductility, and ultimate shear capacity. Results showed that all HFRC beams exhibited improved shear strength and midspan deflection compared to the control mix. The HFRC containing 0.25% PP and 0.5% steel fibers achieved the highest enhancement in shear capacity and deformation that reached 41.7% in ultimate load and 75% in deflection. In contrast, mixtures incorporating basalt fibers showed the weakest performance. The PVA-PP combination demonstrated superior ductility indices due to enhanced fiber–matrix bonding. A numerical simulation using ABAQUS validated the experimental findings, capturing the failure patterns and strain responses. The study highlights the potential of strategically selected fiber combinations for optimizing HFRC in structural applications.