Experimental and computational study of SFRC in-filled steel circular columns under axial compression

Experiments on circular steel tubes filled with steel fibre reinforced concrete (SFRC) and normal concrete have been performed to investigate the contribution of steel fibres to the load bearing capacity of short composite columns. The main variables considered in the test study are diameter to thickness ratio of the steel tube and the percentage of steel fibres added to the in-filled concrete. All the specimens were tested under axial compression until failure state realization. Extensive strain and deformation measurements were taken at compression and tension zones and the results show that 1.00% SFRC in-filled steel columns exhibit enhanced ultimate load carrying capacity, stiffness and ductility coefficient. Also a nonlinear finite element model was developed to study the load carrying mechanism of CFTs using the Finite Element software version ABAQUS. This model was validated using the experimental load-deformation curves and the corresponding modes of collapse. A comparison of the observed load carrying capacity and flexural stiffness with various codal recommendations has been carried out to check the applicability of the expressions recommended by the various codes of practice. Of all the codes compared, Eurocode 4 showed the least variation and is found to be more viable to predict the strength of normal as well as SFRC in-filled steel tubes under axial compression.