When　a　steel　frame　is　subjected　to　an　abnormal　load,　a　sudden　local　failure　due　to　the　loss　of　a　load　carrying　member　may　result　in　progressive　collapse　of　the　entire　structure.　In　this　study,　experiments　and　numerical　simulations　were　performed　to　investigate　the　anti-collapse　performance　of　double　half-span　assemblies　(a　column　connected　with　two　half-span　beams)　with　welded　unreinforced　flange-bolted　web　(WUF-B)　connections　in　a　column　removal　scenario.　Three　types　of　bolted　webs　-　two　bolts　in　one　row,　three　bolts　in　one　row,　and　four　bolts　in　two　rows　-　were　considered.　For　the　post-peak　response,　the　connections　exhibited　a　significant　resistance　recovery　owing　to　the　catenary　action.　The　bolt-bearing　areas　on　the　beam　web　were　prone　to　fracture　owing　to　excessive　compression,　and　the　failure　modes　of　the　web　varied　significantly　with　the　bolt　arrangement.　The　test　results　demonstrate　that　increasing　the　number　of　bolt　rows　is　a　fairly　effective　approach　for　enhancing　the　anti-collapse　performance　of　the　WUF-B　connections.　Numerical　models　were　used　to　further　investigate　the　effects　of　the　bolt　arrangement　on　the　anti-collapse　performance　of　the　WUF-B　connections.　The　results　indicate　that　the　bolt　arrangement　can　directly　affect　the　response　of　the　connections　after　the　first　peak　load,　especially　in　the　catenary　phase.　©　2021　American　Society　of　Civil　Engineers.