Flexural Behavior of Concrete Beams Reinforced with Hybrid (GFRP and Steel) Bars

TLDR

Reinforcing concrete with a hybrid of steel and glass fiber‑reinforced polymer bars offers improved strength, serviceability, and durability. The study aimed to verify this promise and support design by experimentally and theoretically investigating the load‑deflection behavior of concrete beams reinforced with hybrid GFRP and steel bars. Eight beams, including two controls with only steel or only GFRP, were tested while varying reinforcement amount and GFRP‑to‑steel ratio, and theoretical models were applied to analyze load‑deflection behavior. Hybrid GFRP/steel beams with normal reinforcement ratios displayed good ductility, serviceability, and load‑carrying capacity, and the theoretical models accurately predicted load capacity, deflection, and crack width.

Abstract

Reinforcing concrete with a combination of steel and glass fiber-reinforced polymer (GFRP) bars promises favorable strength, serviceability, and durability. To verify its promise and to support design of concrete structures with this hybrid type of reinforcement, we have experimentally and theoretically investigated the load-deflection behavior of concrete beams reinforced with hybrid GFRP and steel bars. Eight beams, including two control beams reinforced with only steel or only GFRP bars, were tested. The amount of reinforcement and the ratio of GFRP to steel were the main parameters investigated. Hybrid GFRP/steel-reinforced concrete beams with normal effective reinforcement ratios exhibited good ductility, serviceability, and load carrying capacity. Comparisons between the experimental results and the predictions from theoretical analysis showed that the models we adopted could adequately predict the load carrying capacity, deflection, and crack width of hybrid GFRP/steel-reinforced concrete beams.