Slender FRP-confined steel-reinforced RAC columns under eccentric compression: Buckling behavior and design calculation models

To extend the structural use of recycled aggregate concrete (RAC) in civil construction, this study has been concerned with the buckling behavior of FRP-confined steel-reinforced concrete (FCSRC) columns under eccentric compression, having RAC infilled between FRP tube and steel section to improve the mechanical and durability performance of RAC. The effects of FRP confinement level, load eccentricity, column height, and replacement ratio of recycled coarse aggregate (RCA) were investigated. The test results revealed that the replacement ratio of RCA had little influence on the buckling behavior of slender FCSRC columns except for the ultimate load-carrying capacity which was mainly governed by the load eccentricity. Besides, a new relative slenderness ratio was recommended for such columns to define their slenderness, and two design calculation models were proposed to determine the secant flexural stiffness and ultimate load-carrying capacity, respectively. A comparison between test and predicted results indicated that design calculation models are applicable to evaluate the buckling behavior of RAC characterized FCSRC columns under eccentric loads, including lateral deflection, second-order bending moment, and the ultimate load-carrying capacity, which facilitates the structural use of RAC in FCSRC hybrid columns.

Automated summary

This study investigates the buckling behavior of FRP-confined steel-reinforced concrete columns with recycled aggregate concrete (RAC) infilled between the FRP tube and steel section. The effects of FRP confinement level, load eccentricity, column height, and replacement ratio of recycled coarse aggregate (RCA) were studied. Design calculation models were proposed and found to be applicable for evaluating the buckling behavior of RAC characterized FCSRC columns under eccentric loads.