Author(s)

J. Heyman

Abstract

A simple statical analysis is made of both straight and curving ("geometrical") flights of stairs. The basic structural action is twist of individual treads, leading to shear stresses in the masonry; such stresses are more harmful than direct compression. Introduction Figure 1 gives a plan view of a simple masonry stair built against two walls of the enclosing chamber. Each of the treads (of which 4 are shown in the sketch of Fig. 2) consists of a slab of masonry t x b x d (Fig. 3); one end of each tread is built in to the wall, while the other end is free. Thus the bottom tread in Fig. 2 rests on the ground; the front edge of the next tread rests on the rear edge of the bottom tread, and one end is supported also by the wall; and so on for successive treads. In practice, the treads may be notched together as sketched in Fig. 4(a); a common form of construction involves the cutting away of the soffit of each tread, Fig. 4(b), t

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