| 摘要 |
PROBLEM TO BE SOLVED: To make fabrication cost low at a site after rust prevention plating by arranging rods for a protection fence on a wall plate, and disposing each upward and downward projection at both the end of a wall plate, and further joining each upper and lower step by the upward and downward projections. SOLUTION: A bracket 11 is fastened in a spiral manner around a support post 1 by welding, and the attachment holes 23 of ribs 22 of a step 2 are matched with two upper and lower holes 12 of the bracket 11 before being tightened by bolts and nuts. In this instance, the downward projection 28 and upward projection 27 of each upper and lower step 2 are matched to be fixed by tightening a nut into a bolt passed through a slot 29, and each rod 3 for a protection fence is fitted in a metal piece 31. A hook part of the metal piece 31 is passed through the cut groove 26 of a wall plate 24, and a bolt is pierced through the attachment hole of the metal piece 31 and the attachment hole 25 of the wall plate 24 to be tightened by a nut, several pieces of which are fastened to each step 2. By this way, the upper step 2 and lower step 2 are joined, and in used of the same steps 2, a spiral staircase can be constructed with the different riser of the step 2.
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