Research Progress on the Axial Compressive Behavior of Rectangular FRP-Confined Concrete Columns

Fiber-reinforced polymer （FRP） composites are lightweight， high-strength， and corrosion-resistant materials. Confining concrete columns by externally wrapping FRP in the hoop direction can significantly enhance their structural performance and durability. While extensive research exists on circular FRP-confined concrete columns， the systematic study of rectangular FRP-confined concrete columns remains comparatively less developed. Therefore， this paper focuses on rectangular FRP-confined concrete columns， presenting a comprehensive review of their axial compressive behavior from both experimental and theoretical modeling perspectives. Regarding experimental research， a database compiling 227 specimens was established. This database was used to investigate the influence mechanism of key parameters， including sectional aspect ratio， corner radius， concrete strength， FRP confinement level， and column size on the mechanical properties of the confined concrete. Valid ranges for these critical design parameters were identified. Regarding theoretical models， three categories of stress-strain relationship models for rectangular FRP-confined concrete （namely single-segment， two-segment， and three-segment models） and corresponding equations for ultimate states were reviewed. The calculation model for the FRP strain efficiency factor was also discussed. The findings of this study offer valuable references for the rational design of rectangular FRP-confined concrete columns.