STUDY ON THE TORSION BEHAVIOR OF CONCRETE FILLED STEEL TUBE COLUMN WITH CIRCULAR SECTION

Tests on concrete filled steel tube column under pure torsion and compression-torsion cyclic load were carried out. The hysteretic curves from the tests were compared with the predicted results calculated by the laminated tubes model, and good agreement was found. Based on the laminated tubes model, the torsion mechanism of concrete filled steel tube columns was analyzed and discussed, including the internal force distribution, strain change regulation and main influencing factors. According to the results from laminated tubes model, a simplified formula suitable for practical design were proposed by the regression method for calculating the torsion capacity and axial load-torsion capacity interaction relations.