Evaluating the Splice Effect on the Flexural Performance of RC Beams Reinforced with Hybrid and GFRP Rebars

Abstract Lap splices play a critical role in the flexural performance of reinforced concrete (RC) members, particularly when non-ductile reinforcement, such as glass fiber-reinforced polymer (GFRP) bars, is used. This study experimentally and numerically investigates the influence of lap splice length on the flexural behavior of RC beams reinforced with GFRP, hybrid (GFRP–steel), and steel bars. Sixteen beams were tested under four-point bending, with varying splice lengths, splice ratios, and reinforcement configurations. Experimental results showed that splice length strongly governs the ultimate load and failure mode of RC beams. When four bars were lap-spliced at a splice length of 0.8 Ld, the steel-reinforced beam achieved the highest ultimate load (85 kN), followed by the hybrid beam, while the GFRP-reinforced beam exhibited the lowest capacity (64 kN) and a more brittle splitting-type failure. Reducing splice lengths below code limits caused ultimate-load decreases exceeding 25% in fully spliced GFRP beams, whereas reductions were significantly smaller for hybrid and steel-reinforced beams. A nonlinear finite element model developed in ABAQUS reproduced the global load–deflection response and crack patterns, with deviations generally less than 10% in the ultimate load. The findings demonstrate the high sensitivity of GFRP lap-spliced members to splice detailing and confirm that hybrid reinforcement provides a balanced response between strength, ductility, and durability, offering a practical solution for durability-critical RC structures.