Behavior of High Strength CFSST Stub Columns With Inner CFRP Tube Under Axial Compressive Load

Abstract

ABSTRACT:The contribution of CFRP (carbon fiber-reinforced polymer) to concrete-filled square steel tube (CFSST) is considered in this paper. Based on the experimental study of six high strength concrete-filled square steel tubular stub columns with inner CFRP circular tube (HCFSST-CFRP), the finite element software ABAQUS is employed to analyze the mechanical behaviors of HCFSST-CFRP stub column under axial compression load. Mechanism of interactions among steel tube, concrete core (includes two parts: innermost concrete and sandwich concrete) and CFRP is analyzed, and a simplified equation of loads shared by innermost concrete and sandwich concrete is given by regression analysis. Longitudinal stress distribution in the concrete section, load shared coefficient and axial load-strain relationships are presented. The confinement effect of the CFRP tube increases ductility of HCFSST stub columns remarkably. Innermost concrete suffers most of axial load after specimen reaching ultimate bearing capacity because of the confinement effect of CFRP tube. CFRP tube begins to work obviously at the descent stage after stub column reached ultimate bearing capacity.

Simplified Design Model for Uni-Axially Loaded Double-Skinned Concrete-Filled-Steel-Tubular Columns With External Confinement

“…From structural point of view, these forms of composite column construction can provide larger axial strength [8][9][10][11][12][13][14][15][16][17][18][19][20], bending stiffness, moment capacity [10,[21][22][23][24], better ductility [25,26,27] and excellent seismic performance [28][29][30][31][32][33][34]. The tubes are both longitudinal reinforcement and formwork, which saves the construction cycle time and cost.…”