BARREL AND SLAB
This shell is a combination of a barrel shell and a slab. The slab must be of sufficient thickness to carry the required bending moment and shear at the end of the span. The small columns shown on the outside edges are for support of the edges only; otherwise, there are no inside columns for this structure. The barrels also must be of sufficient depth at the center of the span for the required bending moment. Since this is half of the depth at the ends, it is evident that the spans possible with this construction are not very great.
This structure would be very suitable when high windows were required to the north and a cantilever slab for sun protection to the south. Then the structural characteristics would be fully utilized.