Hybrid GFRP‐Steel Reinforced One‐Way Concrete Slabs: An Experimental Study on Flexural Performance

Glass fiber reinforced polymer (GFRP) has emerged as a viable alternative to conventional steel reinforcement in concrete structural components. Even though it is not flexible as steel and acts in a brittle manner in terms of stress–strain relationship, it may be useful in addition to steel reinforcement to enhance structural performance. This paper examines the performance of fiber‐reinforced concrete slabs, which are reinforced using steel bars impregnated with GFRP. Four concrete reinforced slabs of the same geometric dimensions (2700 × 600 × 150 mm) and compressive strength of 43.6 MPa were cast with standard concrete. Replacement of steel reinforcement was done using GFRP at 0%, 33.3%, 66.6%, and 100%. These specimens were put to test under two constant loads. It was tested in terms of ultimate load, deflection, stiffness, ductility, energy absorption, and mode of failure. It was found that the outcome of the experimental program showed that the percentage of the reinforcing steel that was substituted with the GFRP had a great influence on the failure mode. The reference slab collapsed in flexural pattern. Substituting 33.3% of the reinforcing steel with GFRP enhanced ultimate load by 17.0% relative to the reference specimen, whereas substituting 66.6 with GFRP enhanced ultimate load by 29.9% relative to the reference. When the GFRP replacement percentage was 100, the failure mode was shear bending which increased the ultimate load by 23.0%. Furthermore, the slab failed with a shear pattern, indicating that the sample lost part of its flexural behavior as the GFRP replacement percentage increased. The effect of the GFRP replacement ratio extended to both ductility and ultimate load. Replacing 33.3% of GFRP resulted in a 30.57% increase in ductility, while replacing 66.6% resulted in a 51.27% increase. However, the specimen reinforced with 100% GFRP exhibited lower ductility compared with the hybrid and steel‐reinforced specimens, which is clearly reflected in the load–deflection curve. The relatively lower ultimate load in the 100% GFRP‐reinforced sample is mainly attributed to the lower modulus of elasticity of this material and its linear elastic behavior up to the moment of rupture, leading to greater deflection and faster crack propagation. This behavior limited stress redistribution and reduced the effective load‐bearing capacity compared with hybrid or steel‐reinforced samples.