Behavior of concrete-filled steel tubular stub columns and beams using dune sand as part of fine aggregate

The concrete using the dune sand as fine aggregate is usually regarded as having low workability and low ductility, although it has certain economic advantages. Using the dune sand concrete as the filling substance of tubular structures is possibly a way to use this kind of material, for the outer tube can provide confinement to its core concrete and thus enhance the ductility of the dune sand concrete. This paper is an attempt to investigate the behavior of concrete-filled steel tubular (CFST) stub columns and beams using dune sand as part of the fine aggregate. A series of CFST stub columns and CFST beams with 10% fine aggregate replacement ratio of dune sand are tested. For the stub column specimens, the main test parameters for stub column specimens are the steel ratio, the concrete strength and the cross-sectional type. For the beam specimens, the test parameter is the cross-sectional depth. The failure modes, load-deformation relation and the strain distribution of composite stub column and beam specimens are reported, and the strength and the ductility of test specimens are discussed using various indexes. The formulae for the compressive and flexural strength of normal CFST members are tentatively used to predict the strength of composite members using dune sand.