This research presents a buckling behaviour of axially loaded fully encased composite columns made with high strength concrete (HSC). Additionally, the research includes experimental study, numerical analysis, and statistical analysis. Three fully encased composite columns (FECC) cast with different cross sections are 200mm x 200mm, 230mm x 200mm, 250mm x 200mm, and 2800mm, respectively. The FECC specimens were made with 80MPa grade of concrete and ISMB 100 x 50 x 7 x 4.2 steel section, including the experimental, analytical, and numerical analyses. The buckling resistance of FECC specimen results were compared to Euro code – 1994 and American Institute of Steel of Construction 360 – 2010 codes. Finite element analysis (FEM) studied the FECC specimens and predicted the buckling resistance compared to the experimental test results. The FEM analysis closely correlated to the experimental results. The statistical analysis was performed on the FECC specimens with current design codes and previous experimental research work. The statistical study compared the experimental test results of buckling resistance and flexural stiffness of FECC specimens to the predicted values from codes. The numerical and statistical analysis results were compared to the experimental test results. Also, it is highly correlated and helps the performance of columns.