Based　on　the　pentagonal　concrete　filled　steel　tubular　(CFST)　mega　columns　of　a　super　high-rise　building,　axial　compressive　behavior　of　pentagonal　CFST　mega　columns　with　different　cross-sections　and　detailing　were　studied.　Monotonic　cyclic　loading　tests　of　3　pentagonal　CFST　mega　column　specimens　were　conducted　under　axial　compression.　3　specimens　were　respectively:　a　single-caved　section　with　a　reinforcement　cage,　a　quadruple-caved　section　without　reinforcement　cage　and　a　quadruple-caved　section　with　reinforcement　cages.　Axial　force-deformation　curves　were　obtained.　The　failure　mechanisms,　residual　deformation　and　elastic-plastic　energy　dissipation　capacities　were　analyzed.　Methods　for　calculating　the　ultimate　bearing　capacity　of　CFST　mega　columns　were　proposed.　Finite　element　simulations　are　carried　out　based　on　ABAQUS　for　analyzing　the　effects　of　cross-sectional　and　detailing　parameters,　including　the　number　of　cavities　and　the　presence　of　reinforcement　cages　on　member　behavior.　The　simulation　results　agree　well　with　the　test　results.　It　is　concluded　that　quadruple-caved　sections　have　greatly　increased　the　bearing　capacity　and　ductility　with　less　residual　deformation　and　better　energy　dissipation　capacity　compared　with　single-caved　sections.　Additionally,　quadruple-caved　sections　with　reinforcement　cages　have　further　increased　the　bearing　capacity,　ductility,　and　the　energy　dissipation　capacity　with　even　less　residual　deformation　compared　with　quadruple-caved　sections　without　reinforcement　cages.　Pentagonal　CFST　mega　columns　with　quadruple-caved　sections　and　reinforcement　cages　have　comprehensively　good　compressive　behavior,　which　can　be　used　in　the　design　of　super　high-rise　buildings.　©,　2015,　Tsinghua　University.　All　right　reserved.