Katariya, S.K.Rautela, Amit2019-02-012019-02-012018-08http://krishikosh.egranth.ac.in/handle/1/5810093217Concrete-filled steel tube (CFST) is the composite structural element which consists of a steel tube in-filled with concrete. The concrete core helps in preventing or delaying the local buckling of steel tube and at the same time steel tube provides confinement to the concrete core for better seismic resistance. CFST structures are widely used in high rise buildings, towers and bridges due to its various advantages like excellent seismic behaviour, strength, ductility, energy absorption capacity, fire resistivity and load bearing capacity. The past studies suggests that the performance of a circular CFST is better than the square or rectangular CFST. However, square and rectangular CFST columns are still increasingly used in engineering practice, for reasons of easy beam-to-column connection, high moment capacities, and aesthetic consideration. This study mainly presents the numerical modelling of square CFST columns under axial loading. To fulfil this, an equation is developed with the technique of regression analysis and then axial load vs strain curve is plotted using the equation to calculate the ultimate load-bearing capacity of the square CFST column. Further, this axial load vs strain curve is compared and validated with the experimental results taken from the different published research papers. An extensive parametric study is also done to investigate the effect of a change in different parameters like width to thickness ratio (B/t), compressive strength of concrete (fck), yield strength of Steel (fsy) and cross sectional size (B x B) on the ultimate load carrying capacity of the square CFST columns.ennullThesis