This　study　experimentally　and　numerically　investigated　the　overall　buckling　behavior　of　steel　box　column　components.　Two　box　section　specimens　were　fabricated　for　axial　compression　tests.　Prior　to　the　tests,　the　material　properties,　initial　geometric　imperfections　and　residual　stress　were　measured.　In　addition,　an　extended　parameter　analysis　was　conducted　using　a　finite　element　model　validated　by　experimental　results　to　evaluate　the　impact　of　geometric　defects　and　residual　stresses　on　the　bearing　capacity　of　unstiffened　and　stiffened　box　section　columns.　A　novel　column　curve　was　proposed　based　on　massive　datasets　of　parametric　models.　The　short　and　long　column　specimens　exhibited　typical　strength　failure　and　buckling　failure　modes,　respectively.　The　initial　geometric　imperfections　and　residual　stresses　slightly　reduced　the　buckling　strength　from　the　models,　with　a　maximum　reduction　in　buckling　strength　owing　to　initial　geometric　imperfections　of　5.2%　and　that　owing　to　residual　stresses　of　6.52%.　The　unstiffened　and　stiffened　box　columns　have　the　same　stability　coefficient　when　the　slenderness　ratio　is　the　same.　Additionally,　the　ultimate　load　capacity　calculation　formula　for　stiffened　box　columns　proposed　in　this　paper　averages　2.20%　higher　than　Class　C　curves　in　JTG　D64-2015,　lies　between　Japanese　and　U.S.　codes,　and　demonstrates　good　accuracy.　©　2025　by　the　authors.