A room $17\mathrm{.}5$ x $10$ m has brick walls all around and it is to be covered with a reinforced concrete slab supported on the walls and on the central beams in the EastWest and North$-$South directions along the middle of the room. The slab has to carry a live load of $4$ kN$/$m$2.$ Assume Mild exposure condition and that M$20$ and Fe $415$ steel. Design the slab which are restrained on top of the walls by the brick masonry built above it