AXIAL COMPRESSIVE BEHAVIOR OF CONCRETE-FILLED CIRCULAR GFRP-THIN WALL STEEL-COMPOSITE TUBES

摘要

Existing experimental investigations have demonstrated that external confinement of concrete with fiber-reinforced polymer (FRP) tubes can significantly enhance both the strength and ductility of the concrete. In addition, FRP tubes can prevent core concrete from aggressive environments and they can also act as stay-in-place formwork. In this paper, axial compressive experiments on ten concrete-filled circular FRP-thin wall steel-composite tubes (CFFST) of 250 mm in diameter and 500 mm in height are presented. The FRP-thin wall steel-composite tubes consist of concrete filled steel tubes which are wrapped with FRP composites. Of the ten test specimens, one concrete-filled thin wall steel tube was tested as a control column and the other nine columns investigated (i) different ratios of steel reinforcement, (ii) different numbers of layers of glass FRP (GFRP) and carbon FRP (CFRP) confinement, and (iii) loading mode (i.e. core concrete only or total cross-section). All experimental results exhibited an ascending load-strain response and the axial load carrying capacity and corresponding axial strain of CFFST columns were larger than that of the control column. The experimental also established the fact that the FRP confinement restricted local buckling of inner steel tube away from the concrete core.