| 摘要 |
PROBLEM TO BE SOLVED: To provide a staircase having a structure capable of reducing the bending amount of each tread and vibration in walking even if the width of the staircase is increased. SOLUTION: This staircase 1 includes a pair of right and left strings 2, 2, a plurality of riser members 3, 3 erected and fixed between the strings 2, 2, and a plurality of tread members 4, 4 erected between the riser members 3, 3 vertically adjacent to each other. The riser members 3 and the tread members 4 are formed of aluminum hollow-section extrusion shape. The front engagement part 4d and rear engagement part 4e of the tread member 4 and respectively engaged with an engagement part 3f formed on the upper part of the riser member 3 and an engagement part 3h formed on the lower part of the riser member 3 on the upper side. The fixing parts 4f, 4g of the tread member 4 are fixed to the fixing parts 3g, 3i of the riser member 3. Further, the right and left ends of the riser member 3 are respectively supported by a support projection (a lower flange 2c) formed along the inside of the string 2.
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