| 摘要 |
<p>PROBLEM TO BE SOLVED: To secure proper tread face width or the like and make a staircase smoothly ascendable by providing an upper tread through a bent staircase part on the upper part of a straight line staircase part, making the angle of the boundary line of the bent staircase part and the upper tread to the boundary line of the bent staircase part and the straight line staircase part and the boundary line with the upper tread plate acute. SOLUTION: An upper tread 13 constituting the upper story floor face 101 of a building through a bent staircase part 12 is provided on the upper part of a straight line staircase part 11, and, in a staircase modifying a passage advancement direction in the bent staircase part 12 at a right angle, an angleθmaking the boundary line A of the bent staircase part 12 and the upper tread 13 to the boundary line B of the bent staircase part 12 and the straight line staircase part 11 is made acute. The upper tread 13 is made trapezoidal, the bent staircase part 12 being trapezoidal is divided into two stages, and constituted of treads 14A, 14B of the whole two stages. Thus, the tread face width of a constant or more is secured on each tread 14A, 14B of the bent staircase part 12 not to give a sense of incompatibility in ascending and descending operation, and reasonable gentle inclination of a constant or less can be secured in ascending and descending operation.</p> |
