Patent ID: 9677273
Date: 2017-06-13
CPC Classifications: E04B,E04C

Claim:
1. A concrete-filled steel column for high load carrying capacity consisting of: an outer longitudinally extending generally vertical tubular shell and an inner longitudinally extending perforated steel tubular shell disposed within said outer longitudinally extending vertical tubular shell and coaxial therewith; four inner vertically extending perforated tubular steel members disposed around said inner longitudinally extending tubular steel shell between said outer longitudinally extending tubular steel shell and said inner longitudinally extending steel shell with axes parallel to said coaxial axes and wherein the diameters of said tubular steel members are equal to or smaller than the diameter of said inner longitudinally perforated steel tubular shell; a mass of cement filling said outer longitudinally extending generally vertical tubular shell and between said inner longitudinally extending perforated steel tubular shell and said outer longitudinally tubular shell; a plurality of polymer caps for closing said perforations in said inner perforated tubular steel members and wherein said polymer caps are meltable in the event of an external fire to allow gases generated thereby to exit the column through the inner tubular members and out of the top of the column; and in which said inner longitudinally extending generally vertical steel shell has a circular cross section; and in which said circular cross section has a diameter of between about 300 mms to 1200 mms; in which said outer longitudinally extending generally vertical tubular steel shell defines a circular cross sectional shape with a minimum diameter of about 500 mms and the inner shell having a minimum diameter of about 150 mm and each of said longitudinally extending steel tubular members each having a maximum diameter of about 150 mm; and in which said mass of concrete is mixed with plastic fibers; and, in which said inner longitudinally extending steel tubular shell includes a plurality of perforations therein for release of smoke and gases, emanating from the heating of concrete, through the inner steel shell and members to the outside at the top of said column; and, which includes a cover and in which said inner steel shell and said steel members are covered at the top of said column such that the cover blows off due to the escape of gases during fire exposure; and, in which 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.