The　bolted-flange　connection　is　used　to　connect　rectangular　HSS　columns　in　prefabricated　multi-story　and　high-rise　steel　structures.　It　may　subject　to　coexisting　axial　compression,　bending　moments　and　shearing　under　the　combination　of　dead,　live,　wind　loads　or　earthquake　action.　The　bearing　performance　is　different　from　that　of　bolted-flange　connections　used　in　pipelines,　towers　and　mast　structures.　To　investigate　the　bearing　performance　of　a　connection　subjected　to　coexisting　compression,　bending　moments　and　shearing,　static　tests　and　a　finite　element　analysis　(FEA)　were　applied　to　12　column-to-column　bolted-flange　connections　with　different　flange　thicknesses,　bolt　edge　distances,　flange　edge　widths　and　bolt　hole　diameters,　as　well　as　one　column　without　connection.　The　effects　of　flange　thickness,　bolt　edge　distance,　flange　edge　width,　and　bolt　hole　diameter　on　the　stiffness　and　strength　of　connections,　bolt　tension　levels,　and　contact　forces　between　flanges　were　obtained　as　well　as　effects　on　the　failure　mode　and　mechanisms　of　the　connections.　Flange　thickness　was　found　to　have　a　considerable　impact　on　the　performance　of　connections,　while　the　bolt　edge　distance　and　flange　edge　width　were　found　to　have　a　lesser　effect.　The　FEA　results　agree　well　with　the　test　results,　verifying　the　finite　element　model　(FEM).　Some　performance　results　that　could　not　be　obtained　through　testing　were　obtained.　Based　on　yield　line　theory　and　T-stub　analogies,　the　load　transfer　mechanism　of　bolted-flange　connections　was　obtained　and　formulas　for　yield-bearing　capacity　are　proposed.　The　results　obtained　from　the　formulas　agree　well　with　the　test　and　FEA　results.