Effect of reinforcement configurations on behavior of non-straight RC beams under torsion: Optimization for construction safety
Sabry Fayed, Moataz Badawi, Mohamed Ghalla, Ehab A. Mlybari, Yahia Iskander, Saad A. Yehia
Abstract
This study investigates the torsional behavior of non-straight reinforced concrete (RC) beams with out-of-plane parts, focusing on reinforcement configurations to optimize construction safety. Ten beams—one straight (reference) and nine non-straight—were tested under four-point bending. Two reinforcement strategies were evaluated: (1) straight bars arranged in horizontal (3 bars), vertical (3 bars), or matrix patterns (4–9 bars) at the contact surface, and (2) closed stirrups (0–4 stirrups) combined with continuous longitudinal bars. Results showed that all non-straight beams failed in torsion at the out-of-plane section. Beams with nine straight bars in a 3 × 3 matrix achieved 40 % higher ultimate load than those with three horizontal bars, while closed stirrups outperformed straight bars, enhancing shear resistance by up to 133 % compared to unreinforced connections. The optimal configuration—four 10 mm closed stirrups with continuous longitudinal bars—restored 63 % of the reference beam’s load capacity and matched its energy absorption. Finite element analysis validated experimental results and confirmed that increasing stirrup diameter improves torsional resistance, with a 70 % capacity gain for diameters up to 12 mm. Findings emphasize the critical role of transverse reinforcement design in non-straight beams, providing actionable insights for safer RC construction.