Concrete-filled steel tubular column for high load carrying capacity and fire resistance

Abstract

A concrete-filled steel tubular column for high load capacity, usually required in tall buildings, includes an outer longitudinally extending generally vertical tubular shell and an inner longitudinally extending perforated tubular steel shell disposed within said outer longitudinally extending vertical tubular shell and coaxial therewith. Further, a plurality of relatively small diameter vertically extending perforated tubular steel members are disposed around said inner longitudinally extending tubular shell between said outer longitudinally extending tubular steel shell and said inner longitudinally extending steel shell with axes parallel to said coaxial axes. The concrete-filled steel column wherein said inner steel shell is centrally disposed within the outer longitudinally extending vertical tubular steel shell and wherein the volume between the outer steel shell and the inner shell is filled with high strength concrete. The perforated inner shell and members have a plurality of meltable polymer plugs or caps on perforations to prevent plastic cement from flowing into or closing the openings during concreting. In the event of fire the plastic or polymer plugs or caps melt and allow gases and smoke to flow into the pipes and up through the inner member and out therefrom at the top of the column The inner vertical tubular shell and members may be subsequently used for injecting grout through the perforations (which get opened during fire by melting of polymer caps) for strengthening the post fire damaged concrete).