Experimental study of clay concrete filled steel tubular stub columns under axial compression

This paper sets out to experiment the behavior of clay concrete filled steel tubular (CFST) stub columns subjected to concentric axial compression. Substituting clay for natural river sand in the infilled concrete reduces the usage of virgin materials and the need for handling the excavated clay on site. Twenty clay CFST stub columns and four reference hollow steel sections were tested. The test parameters were wall thickness of the steel tube, crosssectional size, and clay concrete infill. Results show that, similar to conventional CFST stub columns, the tested clay CFST specimens failed in a ductile manner, in which outward buckling failure mode dominated. Clay concrete was able to ensure the full utilization of the strength of steel when the stub columns attained the ultimate strength. Using clay instead of sand as the fine aggregates slightly reduced the compressive rigidity but did not show a significant effect on the strain corresponding to the ultimate stress. Existing codes for calculating the ultimate strength of conventional CFST columns can be used for clay CFST columns.