BACKSTAY

PROBLEM TO BE SOLVED: To provide a backstay easy in the construction and removal and having a high strength to shorten the construction period and to reduce the construction cost of an arch bridge. SOLUTION: This backstay is provided with a form 8 composed of a sheathing board 9 inclinedly bridged between the back of the end post 2 and an arch abutment 1, and of a timbering 10 for supporting the sheathing board, a plurality of precast blocks 11 continuously laid on the sheathing board 9, and PC steel twisted wires 12 made of PC steel extendedly stretched through inside the precast blocks 11 between the end post 2 and the arch abutment 1. The PC steel twisted wires 12 are arranged in such a way that the intermediate part of the PC steel twisted wires 12 is bridged on the arch abutment 1 and the end thereof is fixed to the end post 2. The adjoining surface of the precast block 11 to be adjoined on the adjacent other precast block 11 is formed so as to be meshed with the other precast block 11.