PURPOSE: To prevent occurrence of bending crack during construction of a PC beam by applying a reversely bending load to the PC beam with the use of a bundle which abuts against the lower surface of the center part of the PC beam by tightening up a wire rope.
CONSTITUTION: A wire rope 8 incorporating a fastener 9 is stretched between a pair of fixtures 1, 1 which have been attached to the lower surface of a laid PC beam 10 at opposite ends thereof. Further, a bundle member 5 incorporating a lower pulley 6 is made to abut against the lower surface 10a of the middle part of the PC beam 10. Then, a wire rope 8 is wound on the lower pulley 6, and then is tightened up by means of the fastener 9 so as to apply a suitable inversely bending load to the middle part of the PC beam 10 through the intermediary of the bundle member 5 on the lower side of the beam 10. That is, the reversely bending load counteracts against a vertical load exerted to the PC beam 10 so that occurrence of bending crack is effectively prevented. Then, after the strength of field-placed concrete in the upper part of the beam and in a floor slab is obtained, the wire rope 8 is slackened for removing the bundle member 5, the fixtures 1 and the like, and the disassembly and withdrawal are made.
SUZUKI SEIICHI
OHASHI HIROKO
INOUE KEIICHIRO
