L 2 y where Mx is moment acting on beams spanning in the shorter direction. 0.047 0.036 0.066 0.049 0.078 0.059 0.045 0.034 Note that a negative moment acts at the support and causes hogging. A positive moment acts at mid-span and causes sagging. This section is satisfactory. Although we could try to reduce slab thickness in other places, we would normally retain a constant thickness and change steel sizes - but only in a manner which did not make the floor unbuildable.
Minimum cost is far more important than minimum weight.
Aquaduct Design Calculate the bending moment on each beam, assuming each beam carries an equal proportion of the total load. The barrier rail is designed to deform by 1m as the impact occurs. Consider 1m length of wall.