Modification of load carrying capacity model for composite column

Nowadays the concrete-steel composite column with the form of full or partial encasement of the steel section has more attraction to the pervasive attention of the people than the reinforced concrete column due to its multi-advantageous character. The maximum load-carrying capacity of a composite column has been predicted by different formulae prescribed by the various codes. Among these codes, EN 1994-1-1:2004 and JGJ 138-2016 are commonly referred to by many researchers for analyzing the load-carrying capacity of composite columns. The formulae used in these codes are based on cross-sectional area and their corresponding yield strength of concrete, steel, and reinforcement bar. The other factors such as the diameter of transversal reinforcement, spacing of ties, slenderness ratio of column, shape factor etc. are not included. In this study, the performance of concrete steel composite columns subjected to axial load had been studied in which steel was fully encased centrally inside the Reinforced Concrete Column. A parametric investigation procedure had been analyzed by ABAQUS software on a series of eighteen samples of concrete steel composite column with three different lengths of the composite column and two different sizes of longitudinal reinforcement. Test results were compared with the results obtained from the prescribed formula of EN 1994-1-1:2004 and JGJ 138-2016 code. A large difference was found between ABAQUS test results and results obtained from the formulae prescribed in the above codes. In this present research, those formulae have been modified accordingly by inscribing the length parameters and load factors by using regression analysis.