Study on Concrete Filled Steel Circular and Square Tubes

Concrete filled steel tube (CFST) is a composite material which is increasingly used in the civil engineering industry. So, it is required to identify the properties of concrete-filled steel tubes as a composite material. This paper focuses on a study conducted on concrete-filled circular steel tubes and galvanised square sections. Concrete filled circular steel tubes were tested under axial compression with three different diameter-to-thickness (D/t) ratios and two different concrete compressive strengths since CFSTs are most effective as compression members. Galvanised steel square sections were also tested for compression capacity and failure mode. Finite element model was developed using the ABAQUS software and two experimental programmes were carried out to find material properties of concrete and steel for finite element modelling and two experimental programmes were carried out to verify the finite element modelling. Galvanised iron square sections were modelled using MIDAS gen software and verified with experimental results for the failure load and failure mode also. The axial capacity of CFST was found theoretically using two different codes and one equation found in the literature. Experimental as well as numerical results showed that the axial capacity of CFST increases as the concrete infill increases and decreases with D/t ratios.