This　study　proposes　a　fully　bolted　connection　joint　for　a　square　steel　column　incorporating　an　octagonal　core　sleeve.　To　ensure　smooth　assembly　of　the　joint　at　the　construction　site,　a　certain　gap　is　maintained　between　the　core　sleeve　and　the　square　steel　column.　However,　this　gap　may　exert　a　certain　influence　on　the　seismic　performance　of　the　joint.　To　enhance　the　seismic　performance　of　the　joints,　the　application　of　self-tapping　bolt　technology　is　recommended　for　optimizing　the　design　of　the　joints.　Based　on　these　considerations,　this　study　designed　and　conducted　quasi-static　tests　on　two　specimens:　the　self-tapping　bolt-octagonal　core　sleeve　flange　square　steel　column　connection　joint　(SOFC)　and　the　traditional　column-column　welded　connection　joint　(TWC).　The　seismic　performance　of　the　two　connection　joints　was　compared　and　analyzed.　The　test　results　demonstrate　that　the　SOFC　specimen　achieves　the　seismic　design　goal　of　＇strong-joints　and　weak-members,＇　with　a　maximum　bearing　capacity　of　−1128.17　kN·m,　which　represents　a　11.42　%　improvement　over　that　of　the　TWC　specimen.　Furthermore,　the　total　energy　dissipation　of　the　two　specimens　across　all　loading　levels　differs　by　11.2　%,　indicating　that　their　seismic　performance　is　comparable.　Additionally,　a　finite　element　numerical　simulation　was　also　performed　to　analyze　the　failure　mode　of　the　SOFC　model　in　the　limit　state,　clarify　its　failure　path,　and　verify　that　the　use　of　self-tapping　bolts　can　effectively　optimize　the　joint　force　transmission　and　improve　the　seismic　performance.　©　2024　Elsevier　Ltd