Experimental and finite element analysis of the flexural performance of concrete beams reinforced with GFRP reinforcing bars

Due to the limitations of traditional steel reinforcement, especially its vulnerability to corrosion in harsh environments, Glass Fiber Reinforced Polymer (GFRP) reinforcing bars are gaining attention as a corrosion-resistant and lightweight alternative. However, its linear-elastic behavior until failure, coupled with a low modulus of elasticity, demands investigating the performance of GFRP bars used in flexural concrete members. To this end, experimental and numerical studies are conducted to understand the effects of concrete compressive strength and reinforcement ratios on the damage resistance of GRRP-reinforced concrete beams. Two compressive strength levels (23.4 MPa and 30.4 MPa) and two longitudinal tensile reinforcement ratios (0.7% and 1.13%), were considered. The fabricated beams were subjected to a monotonic four-point bending test. In addition, a finite element modeling, using ABAQUS software and incorporating the Concrete Damaged Plasticity Model (CDPM) was used to simulate the four-point bending tests of the concrete beams reinforced with GFRP bars, reproducing experimental tests. The results from our study show that beams with higher reinforcement ratios (1.13%) exhibited lower cracking deflections and greater resistance to failure, indicating improved stiffness and load capacity. Conversely, beams with lower reinforcement ratios (0.7%) exhibited larger deflections and lower failure loads. GFRP bar reinforced beams with 23.4 MPa concrete strength demonstrated better cracking resistance than those with 30.4 MPa concrete strength, challenging the assumption that higher concrete strength always results in better crack resistance. All GFRP-reinforced beams failed in a brittle manner with larger deflections compared to the steel-reinforced control beam. Increasing concrete strength improved cracking loads but had a limited influence on failure mode. The FEA results agreed reasonably with experimental data, though they slightly overestimated deflections. GFRP reinforcement enhances the flexural strength and corrosion resistance but presents serviceability and ductility limitations.