Structures of this type have been known and used for a long time, including such composite structures in which a series of steel beams, suitably supported by pillars or other permanent members, carry a reinforced concrete slab in which metallic members, such as cleats, prongs, rods, and elements of various shapes, are attached to or in contact with such steel beams so that the concrete slab is securely anchored to the steel beams to form the desired composite structure. In all of the composite structures without temporary supports. heretofore used, the steelbeams were always designed to carry the entire dead load, which usuallyconsists of the weight of the steel beams plus the weight of the concrete slab united therewith.