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Stairs (staircases) are sets of steps having more than three rises and a flight line under an angle of inclination of alpha (a).
Figure 1 - Single-branch
flight of mortised wooden stairs
Figure 2 - Features of a
staircase (set of steps) 1 upper level, 2 lower level, 3 surface - bottom
landing, 4 surface - top landing, 5 stair flight line, 6 angle of inclination of
the stair flight, 7 stair flight (inclined pan of the stairs)
A set of steps consists of a bottom stair landing, a top stair landing and the flight of stairs.
The angle of inclination (a) of the flight line results from the ratio of flight height and flight length (see Fig. 10).
Stairs are needed for convenient and safe going from one level to another one. They are also necessary for evacuating people in emergency cases.
Figure 3 - Representation of
the two different levels of a staircase - 1 upper level, 2 lower level
A wooden staircase consists of the bottom and top stair landings, the two strings (or string boards) and a number of successive steps. Stair railings provide lateral protection against falling down.
Soft wood may be used for the strings.
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The steps (treads) must be made of hard wood because they are subject to heavy wear. |
The risers are not subject to wear and may be made of soft wood. In the interest of an attractive appearance of the staircase, well-veined hard wood should be used only.
What does the term "stairs" (or "staircase") mean?
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Why should the steps (treads) be made of hard
wood?
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