| 摘要 |
PURPOSE:To dismantle a formwork support safely and easily by pulling out a pin for joining the top ends of a pair of semi-arch trusses, and tilting semi- arch trusses by using a tackle around pins at both the bottoms ends for joining to abutments, as axes. CONSTITUTION:Arch concrete B is placed by using an arch shaped formwork support A, which is erected by making a pin joint 3 at the top of a pair of semi-arch trusses A1, A2 and pin joints 2, 2 at the bottoms thereof to abutments 1, 1. Pulleys 12, 12 are fitted to anchor bolts 11, 11 buried in arch concrete B and ropes 14, 14 of hoisting devices 13, 13 are laid over the pulleys 12, 12 while the ends of the ropes 14, 14 are secured 15, 15 to the upper portions of the semi-arch trusses A1, A2. The pin for joining the semi-arch trusses A1, A2 together is removed, the ropes 14, 14 are drawn out to tilt the semi-arch trusses A1, A2 around joining pins 2, 2 at the bottoms thereof as axes and hang them down. |
