In　order　to　study　the　web-crippling　behavior　of　aluminum　hollow　section　subjected　to　concentrated　load,　sixteen　aluminum　hollow　tubes　with　different　loading　conditions,　bearing　length　and　web　slenderness　ratios　were　tested.　This　paper　also　discussed　a　method　to　improve　the　web　crippling　strength　of　the　aluminum　hollow　sections　by　infilling　the　mortar　as　composite　section,　and　four　aluminum　composite　sections　were　tested.　The　literature　has　reported　lots　of　web　crippling　tests,　but　there　is　few　reports　on　web　crippling　behavior　of　aluminum　composite　sections.　Interior-Ground　(IG)　and　End-Ground　(EG)　loading　conditions　were　adopted,　with　the　specimens　placed　on　the　ground　to　simulate　the　load　of　floor　joists.　Specimens　were　also　placed　on　a　bearing　plate　with　end　(ETF)　or　interior　(ITF)　bearing　load.　The　influence　of　supporting　conditions,　loading　positions,　bearing　length　and　web　slenderness　ratios　on　web　crippling　ultimate　bearing　capacity　and　ductility　of　aluminum　hollow　sections　was　studied.　The　enhancements　of　infilling　mortar　were　also　evaluated.　The　results　obtained　from　the　experiments　show　that　infilling　the　mortar　in　aluminum　hollow　tubes　is　an　effective　method　for　enhancing　the　ultimate　capacity　of　the　web,　especially　for　specimens　under　Interior-Ground　(IG)　condition.　Based　on　the　results　of　parameter　research,　this　paper　proposes　a　series　of　design　formulas　for　well　predicting　web　crippling　ultimate　capacity　of　aluminum　hollow　and　composite　tubes　under　four　different　loading　and　boundary　conditions.　Copyright　©　2018　Tech　Science　Press.