Impact response of steel-BFRP hybrid-reinforced beams designed with different reinforcement equivalence principles

Abstract

To solve the corrosion problems of steel bars in reinforced concrete (RC) structures and brittle damage in pure fiber-reinforced polymer (FRP) reinforced concrete structures, hybrid-reinforced concrete (hybrid-RC) structures combining FRP and steel bars have been proposed. The studies on hybrid-RC structures have focused on static loading conditions, while the structures may also be subjected to impact loading, leading to significant damage. Due to the difference in the properties of FRP and steel bars, FRP bars are always equivalent to steel bars based on different principles in calculation and design, e.g., equal-area, equal-strength, and equal-stiffness. In this work, to investigate the impact behavior of hybrid-RC beams and the influence of design principles, 17 specimens were designed and modeled using Basalt FRP (BFRP) bars replacing steel bars. The results show that the equal-strength-reinforced beams have the smallest damage extent, and the largest impact and reaction forces. While the equal-stiffness-reinforced beams have the greatest damage extent, the beams exhibited a better deformation and deformation recovery capacity. The impact resistance of equal-area-reinforced beams is between the remaining two. Besides, to fully utilize the material performance, for structures with high deformation and damage control requirements, it is recommended to use equal-strength-reinforced beams; for structures that need to reduce residual deflections, impact forces and reaction forces, equal-stiffness-reinforced beams are suggested; and if the economy of the materials is considered, equal-area-reinforced beams may be the preferred choice. The current study could be a reference for impact-resistant design for hybrid-RC structures.