PARAMEYRIC ANALYSIS AND RESTORING FORCE MODEL OF HYSTERETIC BEHAVIOR OF CIRCULAR CONCRETE FILLED CFRP-STEEL TUBULAR BEAM-COLUMN

The lateral load-deflection hysteretic curves at the mid-height and deformation mode of the circular concrete filled CFRP-steel tubular beam-column are simulated by using the finite element software ABAQUS. Comparison between the simulated results and the experimental results shows that the numerical model is reasonable. The interactional forces between the steel tube and the concrete during the full loading process are studied. It is found that the interactional force in the compressive region is larger than that in the tensile region throughout the process, and this force increases dramatically after the steel tube yields. The influences of some parameters, such as layers of the CFRPs, the axial compressive ratio and the slenderness, on the hysteretic curves are analyzed, which shows that the axial compressive ratio has the most obvious effect, as both the lateral load carrying capacity and the stiffness of the beam-column reduces, and a softening stage occurs in the hysteretic curve at the end of the loading process. Finally, the restoring force model of the circular concrete filled CFRP-steel tubular beam-column is proposed, and the calculated results based on this model agree well with those of the finite element simulation.