Performance Investigation Of FRP-concrete-steel Double-skin Square Columns Under Axial Compressive Loading

In recent50years, as a new type of structure form, composite structure has obtained unanimous approval in both academic and engineering circle. Composite structure combines the strong points of concrete and other materials, so it has the following advantages:light weight, high stiffness, seismic behavior, etc. Composite structures which have been applied widely in engineering include:concrete filled steel tubular column, composite beam, composite column, etc. FRP-concrete-steel double-skin tubular columns (DSTCs) are new structure form.This paper designs10square columns which are test under axial compression, and the columns include6DSTCs,2FRP-confined solid columns,2FRP-confined hollow columns. Hollow ratio, diameter-thickness ratio and FRP layers, which have influence on mechanical behavior of the concrete of composite columns, are researched in this paper, and this thesis puts forward formulas of peak stress and peak strain of the concrete of composite columns. Conclusions are drawn as follows:(1) The DSTCs embody good ductility in the last stage of loading, and the strength of concrete of composite columns is improved.(2) The peak stress and peak strain of concrete are improved with the hollow ratio increased. With the diameter-thickness ratio decreased, the peak stress and peak strain of concrete gets improved. With the increasing of the FRP layers, the peak stress and peak strain of concrete get improved.(3) For the peak stress and peak strain of concrete of FRP-confined solid columns, this paper verified the existing formulas with the test values; and on the basis, this paper puts forward new formulas for the peak stress and peak strain of DSTCs.