Akademik Veri Yönetim Sistemi
Structures, cilt.82, ss.1-16, 2025 (SCI-Expanded, Scopus)
Even with decades of experimental and analytical investigation, the shear behavior of reinforced concrete (RC) elements remains one of the most complex and least understood phenomena in structural engineering. The inherently brittle and sudden nature of shear failure makes it particularly critical, especially in stirrupless RC beams where multiple interacting parameters govern the response. Among these, the combined effects of loading rate and fiber reinforcement, particularly hybrid fiber systems, have not been adequately explored in existing research. Motivated by this gap, the present study investigates the shear behavior of stirrupless RC beams cast with self-compacting concrete (SCC) incorporating three configurations: non-fiber, single-type macro steel fiber, and hybrid (macro + micro) steel fiber. The beams were tested under two different loading rates (1.60 mm/min and 40 mm/min) and evaluated in terms of load–time behavior, crack patterns and failure mode, load–deflection response, shear capacity and toughness. The results reveal that the combined effect of the loading rate and hybrid steel fiber reinforcement causes a significant transformation in the shear behavior of stirrupless RC beams. That is, at 1.60 mm/min, the addition of fibers led to an average increase of 103 % in ultimate shear capacity compared to non-fiber RC specimens, while this enhancement reached approximately 152 % at 40 mm/min. Notably, hybrid steel fiber-reinforced RC beams exhibited the highest improvement, achieving up to 163 % higher shear capacity under high loading rate. All in all, the findings of this study not only deepen the understanding of loading rate-dependent shear behavior in fiber-reinforced RC beams fabricated from SCC, but more importantly, they provide a practical foundation for future applications in structural engineering. The demonstrated capacity enhancement—particularly with hybrid steel fiber reinforcement under high loading rates—suggests that fiber reinforcement-based design strategies can effectively replace conventional shear reinforcement in certain scenarios. These results support the development of safer, more ductile, and construction-efficient RC systems for use in dynamically loaded structures such as bridges, seismic zone buildings, industrial slabs, and precast elements.