The use of Concrete Filled Steel Tube CFST is increasingly implemented in the design of modern buildings for their high loading capacity and ductility compared to reinforced concrete or hollow steel columns if worked separately. Changes to structural usage may result in increasing the loads on building columns. This paper presents the experimental test results and non-linear finite element modelling of experimental test program carried on Concrete Filled Steel Tube CFST columns with longitudinal stiffeners as a proposed solution to increase the CFST capacity. The nonlinear analysis has been performed using ABAQUS and the finite element model is validated and verified against the test results conducted in this study. The study extends to include different parameters affecting the design of CFST columns by implementing the validated numerical model. The parameters include the stiffener shape, the number of stiffeners per specimen and the diameter to the tube thickness (D/t) ratio. Behaviour of experimental and numerical models is evaluated by monitoring the load-displacement and resulted deformation shapes. Results conclude that there is a slight increase in the load carrying capacity by adding longitudinal stiffeners that may encourage the use of such system for increasing the existing CFST columns.