we calculate quantity by
area of waist multiply by thicknes of waist it will give us
the volume of waist
then number of steps multiply by tread multiply by riser
multiply by stair width and the total ove 2 it will give us
the volume of steps
and are of steel we know it from design drawing

first,we calculate length of waist by using pythagores rule
and this length multiply by width of waist and multiply by
thickness of waist slab.now for landing,length of landing
multiply by width of landing and multyply by thickness .we
add quantity of waist & landing which will be total
quantity of stair case