ABSTRACT
Many types of stair design can be utilized, ranging from a simple flight spanning between supporting beams, to free-standing ‘scissor’ flights with landings not independently supported, and helicoidal stairs turning through 360° and supported at top and bottom only. The interaction of inclined flights at right angles also obviously considerably restricts the deflections that actually occur. The span of stairs that are supported not on stringer beams, but on landings or structural members spanning at right angles to the direction of the span of the stairs, may be assumed to be the horizontal distance between the supports plus one-half of the width of each landing. The longitudinal force in a stair, or in the sloping part of a combined landing and stair considered as a cranked beam, is generally neglected as it is very small. Bars in stairs may be curtailed according to the simplified requirements described for slabs in clause 3.12.10.3 of BS8110.
