Pre-loaded concrete-filled steel tubular columns and method for fabricating the same

Abstract

The present application relates to a circumferentially pre-loaded concrete-filled steel tubular column, including a steel tube formed from a plurality of steel sheets with two flanges formed at two opposite sides of each of the steel sheets, respectively, and defined with bolt holes therein; and a concrete core provided in the steel tube. Every two adjacent steel sheets are connected with each other by bolts passing through corresponding bolt holes in two adjacent flanges to form the circumferentially pre-loaded concrete-filled steel tubular column.

What is claimed is: 
     
         1 . A circumferentially pre-loaded concrete-filled steel tubular column, comprising:
 a steel tube formed from a plurality of steel sheets with two flanges formed at two opposite sides of each of the steel sheets, respectively, and defined with bolt holes therein; and   a concrete core provided in the steel tube,   wherein every two adjacent steel sheets are connected with each other by bolts passing through corresponding bolt holes in two adjacent flanges to form the circumferentially pre-loaded concrete-filled steel tubular column.   
     
     
         2 . The circumferentially pre-loaded concrete-filled steel tubular column according to  claim 1 , wherein the circumferentially pre-loaded concrete-filled steel tubular column is a hoop pre-tensioned concrete-filled steel tubular column. 
     
     
         3 . The circumferentially pre-loaded concrete-filled steel tubular column according to  claim 1 , wherein the steel tube is one selected from a group consisting of a circular steel tube, a square steel tube, and a regular hexagonal steel tube. 
     
     
         4 . The circumferentially pre-loaded concrete-filled steel tubular column according to  claim 1 , wherein the concrete core is a concrete core made from self-stressing concrete. 
     
     
         5 . The circumferentially pre-loaded concrete-filled steel tubular column according to  claim 3 , wherein the steel tube is the circular steel tube formed from four ¼ arc-shaped steel sheets. 
     
     
         6 . The circumferentially pre-loaded concrete-filled steel tubular column according to  claim 3 , wherein the steel tube is the square steel tube formed from four L-shaped angle steel sheets. 
     
     
         7 . The circumferentially pre-loaded concrete-filled steel tubular column according to  claim 3 , wherein the steel tube is the regular hexagonal steel tube formed from six 120°-angled angle steel sheets. 
     
     
         8 . The circumferentially pre-loaded concrete-filled steel tubular column according to  claim 1 , wherein a reinforcing rib is symmetrically provided at a side of either of two adjacent flanges facing away from the other flange. 
     
     
         9 . The circumferentially pre-loaded concrete-filled steel tubular column according to  claim 1 , wherein a gap is formed between the two adjacent flanges, and an elastic rubber pad is inserted in the gap between the two adjacent flanges. 
     
     
         10 . The circumferentially pre-loaded concrete-filled steel tubular column according to  claim 1 , wherein the bolts are gradually tightened by an increment of torque by firstly tightening a first pair of bolts in a middle of the circumferentially pre-loaded concrete-filled steel tubular column, then a second pair of bolts near the first pair of bolts and symmetrical around a middle point of the circumferentially pre-loaded concrete-filled steel tubular column, then a third pair of bolts near the second pair of bolts and symmetrical around the middle point of the circumferentially pre-loaded concrete-filled steel tubular column, and so on, until all the bolts are tightened. 
     
     
         11 . The circumferentially pre-loaded concrete-filled steel tubular column according to  claim 10 , wherein the increment of torque is 10-50 N·m. 
     
     
         12 . The circumferentially pre-loaded concrete-filled steel tubular column according to  claim 1 , wherein a steel wire mesh is welded on an outer surface of each of the steel sheets. 
     
     
         13 . The circumferentially pre-loaded concrete-filled steel tubular column according to  claim 12 , wherein a fire-proof cement mortar is coated on the outer surface of each of the steel sheets. 
     
     
         14 . A method for fabricating the circumferentially pre-loaded concrete-filled steel tubular column according to  claim 1 , comprising the steps of:
 step 1: cutting the steel sheets into desired size, and forming the bolt holes in the steel sheets;   step 2: bending the steel sheets into desired shapes with the two flanges formed at the two opposite sides of each of the steel sheets, wherein the bolt holes are located in the flanges;   step 3: connecting every two adjacent steel sheets by tightening the bolts passing through the corresponding bolt holes in the two adjacent flanges, with a gap left between the two adjacent flanges, filling the gap with elastic rubber, and sealing the gap with an adhesive tape;   step 4: filling concrete into the steel tubes, and curing to solidify the concrete to form a concrete-filled steel tubular column; and   step 5: gradually tightening the bolts by an increment of torque by firstly tightening a first pair of bolts in a middle of the concrete-filled steel tubular column, then a second pair of bolts near the first pair of bolts and symmetrical around a middle point of the concrete-filled steel tubular column, then a third pair of bolts near the second pair of bolts and symmetrical around the middle point of the concrete-filled steel tubular column, and so on, until all the bolts are tightened.   
     
     
         15 . The method according to  claim 14 , wherein the increment of torque is 10-50 N·m. 
     
     
         16 . The method according to  claim 14 , further comprising welding a steel wire mesh on an outer surface of each of the steel sheets. 
     
     
         17 . The method according to  claim 16 , further comprising coating a fire-proof cement mortar on the outer surface of each of the steel sheets.