| 摘要 |
<p>PROBLEM TO BE SOLVED: To form a compact spiral stairway of which the riser and the step tread are made in favorable length and the gradient is under a fixed angle so as to insure the utilized space in a building by fitting a spiral stairway reversely changing the advancing direction around a handrail provided on the center part. SOLUTION: This stairway is constituted of a lower side rectilinear stair way 2, a spiral stairway 3 of five steps, and an upper side rectilinear stairway 4, a handrail 39 having section of 50-75mm radius is provided on the center part of the spiral stairway 3, and the advancing direction is changed by 180 by the spiral stairway 3. In the spiral stairway 3 of five steps, the riser is 195-210mm, the length of the step tread is 195-230mm, and the gradient is set under 45 deg.. The advancing direction can be changed by 180 deg. by the spiral stairway 3 fitted around the handrail 39 provided on the center part, and hence the length of the step tread can be enlarged. In addition, because a stair landing is not provided, the riser can be heightened even at setting the gradient of the spiral stairway 3 under 45 deg., and as a result the number of steps can be reduced. Hereby the stairway can be compacted, and the space in a building can be effectively utilized for a place except a stairway.</p> |
