Influence of GFRP Confining Tube Parameters in Double-Skin Tubular Short Columns under Axial Loading

Abstract

Abstract Composite construction with steel and concrete has become a widespread solution in modern construction practices because of its inherent properties such as high strength-to-weight ratio, good corrosion resistance, and high stiffness. Concrete-filled fiber-reinforced polymer (FRP) steel double-skin tubular compression members as vertical load–carrying members in buildings helps in optimizing the advantages of three materials: steel, concrete, and FRP. This study investigates the axial compressive behavior of short, concrete-filled glass fiber–reinforced polymer (GFRP) steel double-skin tubular (GSDST) columns and concrete-filled GFRP tubular (CFFT) columns. Parameters such as the number of FRP layers, hollow section ratio (HSR), variation of diameter of the inner steel tube, and the angle of orientation of the fibers have been examined in this investigation. The experimental study was carried out by performing a monotonic axial compressive loading condition. Three different angles of fiber orientation, 0° along the hoop direction, 45°, and 0°/90° with respect to the axis of the column, were adopted in this study. The ultimate load-carrying capacity, axial displacement, axial and horizontal strains, and failure modes were observed. The experimental results indicate that the structural performance of GSDST columns is significantly influenced by GFRP tube thickness, inner steel-tube diameter, and fiber-orientation angle. Maximum displacement was observed in the specimens with high HSR, thus showing a ductile characteristic in the axial load-displacement behavior. The load-carrying ability of the specimens decreased as the HSR increased. The load-carrying capacity of the specimens increased with the increase in outer GFRP tube thickness. This study demonstrates that GFRP tubes can be used efficiently in the construction field as vertical load–carrying components by enhancing the axial behavior of FRP steel double-skin tubular columns.