Concrete-filled square steel tubular column with built-in spiral stirrup

[0023] Specific embodiment: The square steel tube concrete column with built-in spiral stirrups of this embodiment is composed of square steel tube 1, spiral stirrup 2, longitudinal steel bar 3 and core concrete 4. The inner wall of spiral stirrup 2 is provided with longitudinal steel bar 3 to form a spiral reinforcement cage. Place the spiral reinforcement cage at the center of the square steel tube 1, and the central axis of the spiral reinforcement cage coincides with the central axis of the square steel tube 1, and fill the inner space of the square steel tube 1 with core concrete 4 to form a square steel tube concrete column with built-in spiral stirrups.

[0024] The heights of the spiral steel bars 2 and the longitudinal steel bars 3 and the square steel pipe 1 described in this embodiment are the same. The longitudinal steel bars 3 are tied or welded to the inner wall of the spiral stirrup 2 and the minimum distance from the inner wall surface of the square steel pipe 1 to the outer surface of the spiral stirrup 2 is 30-50mm. The square steel pipe 1 can be made of Q235 steel, Q345 steel, Q390 steel, and Q420 steel. The diameter and spacing of the spiral stirrup 2 and the diameter and number of the longitudinal steel bars 3 are determined according to the wall thickness and section size of the square steel pipe 1. The number of steel bars 3 is not less than 4, the spiral stirrup 2 is cold-formed by HPB300 or HRB335 steel bars with a diameter of 6-12mm, the longitudinal steel bars 3 are made of HRB335 or HRB400 steel bars with a diameter of 10-16mm; the core concrete 4 is made of Ordinary concrete or high-performance concrete.

[0025] The square steel tube concrete column with built-in spiral stirrups, the built-in spiral stirrups restrain the core concrete, the square steel tube restrains the core concrete, and the concrete between the square steel tube and the spiral stirrup restrains the spiral stirrup. Effectively suppress the local buckling of the steel plate, improve the bearing capacity and ductility of the concrete-filled square steel tube column, and give full play to the performance of the material, so that the concrete-filled square steel tube column with built-in spiral stirrups has high bearing capacity, good ductility, superior seismic performance, and simple construction , Features of good economy.