Axial Behavior of Concrete-Filled Double Skin Steel Tubular Stub Columns Filled with Demolished Concrete Lump

Abstract

To analyze the axial compression bearing capacity of concrete filled double skin steel tubular (CFDST) stub columns which are filled with demolished concrete lump, twelve stub columns are tested. The main experimental parameters were the diameter-to-thickness ratio, mixing ratio and hollow section ration.Load-displacement curves and failure mode were analyzed, the compressive capacity determined from related design rules were compared with the peak load obtained in the tests. All specimens have a good performance of ductility and late bearing capacity. When the width-thickness is 72 and have a same mixing ratio, CFDST have the same bearing capacity with CFT. When the mixing ratio is 0 and width-thickness is 120, the bearing capacity of CFDST increase 16% than CFT. When the new concrete have similar compressive strength with old and mixing ratio is 25%, the bearing capacity of CFDST increase 18.8% than CFT.