To　study　the　stress　concentration　factor　(SCF)　in　the　concrete-filled　steel　tubular　K-joints　with　array-arranged　internal　stud　(CFST　KSA-joint),　the　CFST　KSA-joints　full-size　specimen　tests　were　carried　out,　the　accuracy　of　the　solid　finite　element　(FE)　nonlinear　analysis　method　was　validated,　the　mechanism　of　the　effect　of　internal　stud　on　the　SCF　of　CFST　KSA-joints　were　revealed,　the　theory　of　equivalent　wall　thickness　was　established,　a　simplified　curved　beam　with　equivalent　spring　support　was　proposed,　and　the　wall　thickness　correction　coefficient　was　derived,　a　CFST　KSA-joint　SCF　calculation　method　with　high　accuracy　was　developed.　The　key　study　findings　indicate　that　the　deployment　of　array-arranged　internal　studs　can　effectively　mitigates　stress　concentration　in　concrete-filled　steel　tubular　K-joints　(CFST　K-joints),　resulting　in　an　88.7　%　reduction　in　SCF.　Comparison　of　FE　and　test　results　showed　a　maximum　deviation　of　only　6.30　%　in　displacement　and　5.14　%　in　hot-spot　stress.　Employing　the　CFST　K-joints　SCF　calculation　method　to　calculate　the　CFST　KSA-joint　SCF　has　an　error　of　up　to　42.3　%.　Sensitivity　analysis　reveals　that　CFST　KSA-joint　chord　wall　thickness　and　inclined　angle　of　the　brace　to　the　chord　significantly　influence　SCF.　Furthermore,　a　positive　correlation　was　observed　between　stripping　distance　and　hot-spot　stress　at　the　chord＇s　tensile　side.　The　SCF　decreases　with　increasing　stud　diameter.　Utilizing　the　equivalent　wall　thickness　theory,　the　derived　CFST　KSA-joint　SCF　calculation　method　exhibits　an　error　lower　than　19.6　%,　representing　a　127　%　improvement　in　accuracy　compared　to　CFST　K-joints　SCF　calculation　methods　that　do　not　consider　the　stud.　©　2024