Abstract: A composite floor structure is disclosed in which a plurality of corrugated sheets having crest portions which slope downwardly at each end thereof are supported on the top surface of a plurality of spaced I-section supporting beams. Studs are welded directly to the top surface of the I-beams directly over the beam's webbing to securely connect the beams to an overlying concrete slab, thereby creating a composite action between the beam and slab and increasing the load carrying ability of the I-beams. By providing a sufficient volume of concrete around the studs, each stud is completely effective. Embossments may be provided in the sheets to also create a composite action between the sheets and the slab causing the entire structure to act as a single composite unit to resist vertical gravity loads (bending) and in plane horizontal wind or seismic loads (shear).