To　study　the　effect　of　circumferential　gaps　on　the　seismic　Performance　of　concrete-filled　steel　tube　structures,　low-cycle　loading　tests　were　conducted　on　concrete-filled　steel　tube　columns　to　explore　the　effects　of　circumferential　gaps,　steel　tube　thickness,　built-in　studs,　and　section　types　on　the　failure　modes,　hysteretic　Performance,　ultimate　horizontal　bearing　capacity,　rotation　ductility　factor,　stiffness　and　strength　degradation,　and　energy　dissipation　capacity.　Based　on　the　finite　element　analysis,　the　mechanism　and　influences　of　the　stud　arrangement,　gap　rate　and　axial　compression　ratio　on　concrete-filled　steel　tube　columns　with　circumferential　gaps　were　obtained.　The　results　show　that　the　circumferential　gap　significantly　reduces　the　constraint　effect　of　the　steel　tube　on　the　core　concrete,　weakens　their　cooperative　work　ability,　causes　concentrated　damage　to　the　core　concrete　and　makes　its　failure　premature.　The　ultimate　horizontal　bearing　capacity　of　the　specimen　decreases　by　6.　50%,　and　the　rotation　ductility　factor　decreases　by　22.　83%.　The　built-in　studs　can　improve　the　constraint　effect　of　the　steel　tube　and　significantly　improve　the　ductility　Performance　of　the　specimen.　The　rotation　ductility　factor　of　the　specimen　is　increased　by　up　to　49.　45%.　Thicker　steel　tube　can　alleviate　the　adverse　effects　of　gaps　on　the　seismic　Performance　of　specimens　and　improve　the　bearing　capacity　and　energy　dissipation　capacity　of　the　specimens　with　circumferential　gaps.　Compared　with　circular　cross-section　specimens,　circumferential　gaps　will　cause　rectangular　cross-section　specimens　to　fail　earlier　and　reduce　their　ductility　Performance.　Finally,　a　calculation　method　for　the　ultimate　horizontal　bearing　capacity　of　concrete-filled　steel　tube　columns　with　circumferential　gaps　was　proposed　and　verified.　The　research　results　provide　a　reference　for　the　safety　assessment　of　concrete-filled　steel　tube　structures.　©　2024　Chinese　Vibration　Engineering　Society.　All　rights　reserved.