| 摘要 |
PROBLEM TO BE SOLVED: To provide a spiral stairway structure facilitating a walk for going up and down a spiral stairway part by lengthening a walking direction dimension on the turning center part side of each step part in the spiral stairway part. SOLUTION: The spiral stairway part 20 has a plurality of step parts A-C formed of a plurality of tread members. Out of these step parts A-C, the walking direction in the lowest step part A and the walking direction at the highest step part C form an angle. The upper end of a first linear stairway part 21 is connected to the lowest step part A, and the lower end of a second linear stairway part 22 is connected to the highest step part C. The position of the turning center part D of the spiral stairway part 20 is more distant from the spiral stairway part 20 than the position of an intersection G between an extension line E toward the spiral stairway part 20 side from the turning inside surface of the spiral stairway part 20 in the first linear stairway part 21, and an extension line F toward the spiral stairway part 20 side from the turning inside surface of the spiral stairway part 20 in the second linear stairway part 22. COPYRIGHT: (C)2010,JPO&INPIT
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