This study investigates the development of cracks and the enhancement of ductility in ‎concrete beams by introducing newly designed hybrid GFRP rebars incorporating polyurethane ‎foam cores as a means to overcome the well-known limitations of conventional GFRP ‎reinforcement. Although reinforced concrete is widely used due to its high compressive ‎strength, economic feasibility, and adaptability to various structural applications, the corrosion ‎of steel reinforcement remains a major concern that can significantly reduce structural ‎durability and increase maintenance costs. GFRP rebars have emerged as a promising ‎alternative due to their excellent corrosion resistance, low weight, and favorable mechanical ‎properties; however, their inherently low elastic modulus often leads to excessive deflection, ‎wider cracks, and brittle failure modes in concrete members. To address these drawbacks, this ‎research proposes a hybrid GFRP rebar system in which a lightweight and highly energy-‎absorbing polyurethane foam core is embedded to reduce brittleness, enhance deformation ‎capacity, and improve flexural performance. Four concrete beam specimens—one reinforced ‎with steel rebars, one with standard GFRP, and two with hybrid GFRP rebars containing 4-mm ‎and 8-mm foam cores—were tested through laboratory experiments and numerical simulations ‎using ABAQUS to evaluate flexural behavior, crack patterns, and ductility indices. The ‎experimental and numerical results exhibited strong agreement, confirming the reliability of the ‎adopted CDP model in simulating concrete behavior and failure mechanisms. Beams reinforced ‎with hybrid rebars demonstrated notably improved ductility compared with standard GFRP, ‎with the 8-mm core specimen showing a 131% increase in ductility over the standard GFRP ‎beam and a 37% increase over the 4-mm core specimen. Furthermore, the failure modes shifted ‎from brittle shear failure in the standard GFRP beam to shear-flexural and predominantly ‎flexural failures in the hybrid beams, indicating a more uniform stress distribution and enhanced ‎energy absorption due to the foam core. These findings highlight the potential of polyurethane-‎foam-integrated GFRP rebars as an innovative and effective solution for improving ‎serviceability, ductility, and overall structural performance in concrete beams.‎