Abstract: In order to study the flexural behavior of concrete slabs with GFRP bars, based on the the assumption of plane section, condition of internal force and deformation compatibility condition, the calculation formula of flexural capacity of GFRP reinforced concrete slabs under the two design cases of under-reinforced and proper amount of extra-reinforced is deduced. By the 8 groups of tests of GFRP slabs with different reinforcement ratio and concrete strength grade of concrete, the calculation formula of flexural capacity is verified. At the same time, the law between the variation of flexural capacity and reinforcement ratio, concrete strength is studied. The results show that the ultimate bearing capacity obtained by the experiment is in good agreement with the theoretical bearing capacity calculated by the formula, which can accurately reflect the calculation process of flexural strength of GFRP concrete slab. The failure mode of the design elements of the right amount of super reinforced concrete is destroyed by the crushing of concrete, which is more conducive to improving the safety performance of GFRP reinforced concrete slabs. At the same time, in order to ensure that the GFRP bar is not broken before the flexural capacity of concrete slab reach the maximum, it is proposing that the ratio of the balanced reinforcement ratio is of 1.4 times of the reinforcement ratio. With the increase of reinforcement ratio of GFRP reinforced concrete slab, the flexural capacity increases gradually, security reserves are also gradually increased. The flexural bearing capacity of GFRP reinforced concrete slab increases with the ratio of reinforcement ratio and concrete strength.

Key words: GFRP bars, concrete slab, flexural capacity, reinforcement ratio