Flexural Response of GFRP–UHPC Composite Slabs under a Hogging Moment

Abstract

A lightweight glass fiber–reinforced polymer (GFRP)–ultrahigh performance concrete (UHPC) composite slab of high strength is proposed in this paper, having a reduced weight with respect to a composite slab with GFRP and normal concrete (GFRP–NC), and improved corrosion resistance compared to the steel–UHPC. Experiments are conducted on GFRP–UHPC composite slabs subjected to hogging moment. Their behavior is compared to that of a steel–UHPC composite slab. The effect of the steel fiber content and reinforcement ratio on their flexural performance is discussed. The cracking load and ultimate bearing capacity of the composite slabs are investigated. Their failure modes and failure mechanisms are analyzed. The results indicate that there are 1–3 primary cracks, with the majority of cracks distributed in the pure bending region. An increase in the reinforcement ratio causes significant bending stiffness, ultimate bearing capacity, and smaller maximum crack width, restraining the development of cracks. The effect of steel fiber content on their flexural performance is minimal, and lesser than the reinforcement ratio. Under the same condition, the self-weight of GFRP–UHPC composite slab is reduced by 26.4% compared to the steel–UHPC composite slab. However, the ultimate bearing capacity of the GFRP–UHPC composite slab is only reduced by 15.9%. The cross-sectional stress method is introduced to calculate the cracking load and achieve good agreement with experimental results. The proposed method gives more accurate results than the transformed section method. In addition, the calculation method for the ultimate flexural bearing capacity of the composite specimens is suggested and validated by the experimental results, presenting satisfactory accuracy.