This study investigated the torsional performance of reinforced concrete (RC) beams using spliced reinforcement bars. Inadequate lap splice lengths were specifically employed to investigate the influence of diminished splice length on torsional capacity, torsional ductility, and torsional toughness. Insufficient splice lengths are especially important in practice, since increasing splice length in FRP-reinforced structures elevates material cost, while excessively splices may lead to reinforcement congestion that restricts adequate concrete placement. A new splice strengthening approach utilizing Carbon Fiber Reinforced Polymer (CFRP) sheets was implemented, applied transversely around the splice zone and covered with resin to enhance confinement and improved bond strength. The novelty of this study resides in the new CFRP configuration developed to strengthen inadequate lap splices of GFRP bars under pure torsion, a condition not previously investigated in comparison to flexural and shear loads. Seven RC beams were fabricated, cast tested under pure torsion to examine the effects of splice length, CFRP strengthening, and stirrup spacing. Results indicated that the shortest substandard splice affected torsional capacity by approximately 36.45%, while torsional ductility and toughness were reduced by up to 36.76% and 70.7%, respectively, in comparison to a beam with continuous bars. Extending stirrup spacing from 100 to 150 mm reduced torque by 15% while significantly impacting ductility. The strengthening of CFRP significantly improved ultimate torque capacity, torsional ductility, and toughness. Finally, this transverse wrapping technique may offer practical on-site benefits, as its enhanced confinement may allow minimizing the required splice length while preserving acceptable torsional performance, and it can be applied manually without required instruments compared to other methods, including welding and couplers.
