Slenderness limit for hybrid FRP-concrete-steel double-skin tubular columns

This paper analyzes hybrid FRP-concrete-steel double-skin tubular columns of different lengths based on numerical method. Parametric study is carried out on the parameters including eccentricity ratio, normalized eccentricity, void ratio, diameter-to-thickness ratio, yield strength of steel tube, confinement stiffness ratio and strain ratio, and a simplified formula which can be used in practical design to calculate the slenderness ratio limit is presented. This formula provides precise and conservative results compared with the results of analysis software.