The corrosion of reinforcement embedded in concrete bridge deck slabs has been the cause of major deterioration and of high costs in repair and maintenance. Fibre reinforced polymers (FRP) exhibit high durability in combination with high strength and light weight. The majority of research with FRP bars for reinforcing concrete has been on simply supported beams and slabs where the low value of elasticity of FRP has meant that the service behaviour has been critical. These differences have been attributed to the low value of elasticity of many FRPs compared to steel. However, laterally restrained slabs, such as those in bridge deck slabs, exhibit arching action or compressive membrane action (CMA), which has a beneficial influence on the service behaviour such as the deflection. Based on the previous research on CMA in steel reinforced concrete bridge deck slabs, a modified theoretical method were established according to the material properties of GFRP reinforcement. The proposed prediction method showed a good collection of some reported GFRP reinforced slabs experimental tests.