Bending moment–curvature and sustainability assessment of RC beams with steel and graphene-GFRP reinforcements

The increasing concerns about the durability limitations of traditional reinforced concrete structures have intensified the pursuit of more sustainable and corrosion-resistant construction materials. Among these, glass fiber-reinforced polymer (GFRP) rebars have gained attention due to their high strength and excellent resistance to chloride ingress and carbonation. However, their small Elasticity Modulus and low ductility remains a critical drawback. This study investigates the moment-curvature response and ductility of reinforced concrete beams using both conventional steel rebars and graphene-enhanced GFRP rebars. A computational model was developed in MATLAB to simulate the mechanical performance of the beams, and the results were validated against experimental data from the literature. Beyond structural metrics such as ultimate moment and energy dissipation, the analysis incorporated a carbon footprint assessment based on material-specific CO₂ emission factors. Results show that GFRPg-reinforced beams achieved a 12% higher ultimate moment compared to steel-reinforced beams but exhibited a 16% reduction in curvature capacity and a 47.8% lower energy dissipation, confirming their brittle behavior. When CO₂ emissions were normalized by structural capacity, GFRP showed better performance in strength-based efficiency but was outperformed by steel in energy-based metrics. Although GFRPg provides improved corrosion resistance and mechanical strength, its limited deformability must be carefully considered in applications where post-peak performance and energy absorption are critical.