Concrete Encased Steel (CES) structural system consisting of steel and fiber reinforced concrete (FRC) is a new proposed composite structural system. The aim of this research program is to evaluate the deformability under seismic actions of the CES columns with encased-steel of H-shaped section. In existing studies by the authors the influence of the axial force ratio, the H-shaped steel ratio and the shear span ratio on the deformation capacity were presented. Also a formulation for the evaluation of the column deformation capacity was proposed. In this study the influence of the concrete fiber contents ratio (percentage of fiber volume to concrete volume), and the flange width of H-shaped steel on the deformation capacity is examined Using the above five parameters, a new formulation was proposed and its validity was verified by comparing it with the test results in this paper.