Effect of Diameter of Fulcrum Roller on Shape of Rebar in Bending

The strength of building is increased by using rebars. The bent rebar is obtained with a bending machine. In the bending machine, there are the fulcrum roller, circular roller, and rebar receiver. The rebar was placed in the contact with rebar receiver. Then the circular roller rotates around the central fulcrum roller to a set angle(θF). Thereafter, the circular roller returns to the initial position. Then the bent shape of the rebar is influenced by the diameter of the fulcrum roller. The diameter of the fulcrum roller is determined by the trial results and the experience. In this paper, the effect of diameter of the fulcrum roller on shape of rebar in bending is reported. The experimental material is SD345 (JIS G3112) and yield stress 398 MPa. The bending deformation of rebar was photographed with a camera. The following conclusions were obtained from the experimental results. An interior angle formed by two linear parts of bent rebar was decreased with increasing the diameter of fulcrum roller. The length of area with constant radius of curvature of bent rebar was increased with increasing the diameter of fulcrum roller.