The behaviour of Glass Fibre-Reinforced Polymer (GFRP) bar reinforced concrete beams varies significantly from the behaviour of traditional steel bar reinforced concrete beams. This paper numerically investigates the response of GFRP bar reinforced concrete (GFRP-RC) beams under monotonic loads. This paper also presents the details of a three-dimensional Finite Element (FE) model for GFRP-RC beams under monotonic loads. The results of the numerical modelling have been validated against the experimental results of nine GFRP-RC beams. The results of the FE analysis have been found to be in very good agreement with the experimental results. Furthermore, a parametric study is carried out to investigate the effects of the reinforcement ratio, compressive strength of concrete, and shear span to effective depth ratio on the response of GFRP-RC beams. The effects of these parameters on the load-midspan deflection behaviour, energy absorption capacity, and failure modes of GFRP-RC beams have been adequately discussed in this paper.