STAIRS, LANDINGS AND CANTILEVER ACCESS MAY BE DESIGNED FOR LIVE LOADS (SUPER IMPOSED LOADS ON FLOORS)

DESIGN OF STAIR CASES:--Stairs are of several types (1) A sloping slab spanning from one floor to another floor or from end to a landing, and supported on the two side walls or on sloping stringer beams (2) Separate slab for each step attached to one central sloping beam .(3)Steps cantilevered from a side wall (One end fixed into the wall ) where the wall is of ample thickness (4) Spiral stairs with slabs cantilevered from a central column.(5) Free spanning spiral stairs .Stairs ,landings and cantilever access balconies may be designed for a load of 300 kg / sq mt for residential and office buildings and 500 kg / sq mt for public places and warehouses .Service stairs for maintenance,such as in water tanks ,back side court yards of residences etc may be designed for 150 kg / sq mt .The slab portion under the (saw tooth)  projections of steps is called "waste" and it's depth is measured normal to the slope of the slab . This waste is considered to take the whole load and is designed as an ordinary slab partially fixed with WL/10 where ends are built into walls ,and with WL/12 where ends are monolithic with the transverse beams at bottom and top .It is common practice to provide transverse beams at top and bottom -at junctions of landing and sloping flight .Where transverse beams are omitted ,flight is a continuation of the landing or landings. Landings usually have the same size as the waste slab and where a landing serves two flights of stairs at right angles to each other ,it should be reinforced in two directions .The pitch or slope of a stair case should not be more than 40 to 30 degree is common .