Axial Stress–Strain Model of LRS-FRP–Confined Rectangular Concrete Prisms Allowing for the Size Effect and Its Application in Flexural Analysis of Beams

Abstract

Large rupture strain fiber-reinforced polymer (LRS-FRP) composites exhibit a large rupture strain exceeding 5%, thereby enhancing the ductility and strength of concrete as a confinement reinforcement with notable energy dissipation capability. Nevertheless, available approaches are empirically derived from small-sized specimens, which renders them unsuitable for practical structures with larger sizes or aspect ratios. In this study, a passive stress–strain model for concrete wrapped by LRS-FRPs under concentric loading is proposed by incorporating partial interaction shear friction and bond-slip mechanisms. This model accommodates the size effect and a corresponding design equation is proposed to ensure the strain-hardening behavior of LRS-FRP-wrapped concrete prisms. The proposed passive stress–strain model is then employed in the segmental analysis to simulate the behavior of LRS-FRP-wrapped concrete beams considering the size effect and the confinement effect. Finally, a parametric study is conducted to investigate the effects of LRS-FRP thickness and longitudinal reinforcement on the behavior of beams.