STEEL PIPE CONCRETE MEMBER

PROBLEM TO BE SOLVED: To increase the bearing force and toughness of concrete to reduce the thickness of a rectangular steel pipe for cost reduction by embedding in each end of the rectangular steel pipe a plurality of spiral reinforcing bars by which concrete packed inside is constrained. SOLUTION: Four spiral reinforcing bars 10 aligned in parallel on their cross sections and constraining filling concrete 2 at each constraining area 11 are embedded in each end of a rectangular steel pipe 1. The reinforcing bars embedded in the ends of the rectangular steel pipe 1 may either be buried in the ends of the rectangular steel pipe 1 as cage reinforcement formed when a plurality of parallel-cross reinforcing bars comprising two horizontal bars arranged to cross another horizontal bar at right angles are connected together by axially extending auxiliary reinforcing bars placed at four corners, or be formed into another shape splitting the concrete 2 into plural constituting areas. Thereby the entire concrete 2 is given a high constraining force, so that bearing forces and toughness can be greatly increased. Therefore, the thickness of the rectangular steel pipe 1 can be reduced for cost reduction.