Axial Capacity of Concrete-Filled Steel Elliptical Hollow Sections

Abstract

Concrete filled steel tube (CFST) columns are becoming increasingly popular due to the advantages they offered. They are not only considered aesthetically pleasing but can also offer significant improvement in axial capacity without increases in crosssectional area being required. Elliptical steel hollow sections represent a recent and rare addition to the range of cross-sections available to structural engineers, however, despite widespread interest in their application, a lack of verified design guidance is inhibiting uptake. The use of elliptical steel hollow section with concrete infill is new and innovative, not only provides the advantage mentioned above, but also on the basis of both architectural appeal and structural efficiency. The aim of this paper is to investigate the behaviour of the elliptical CFSTs under axial loading. A total of 12 specimens were tested with wall thicknesses of 4 mm, 5 mm, 6.3 mm and concrete core strength of 30 MPa. This paper reported on the behaviour of concrete filled elliptical hollow sections under axial load. The effect of the wall thickness of the steel section, the bond between steel and concrete and the concrete confinement are presented.