Nucor Corp. and Wilmington, Delaware-based Asia Fastening were assigned Tuesday a patent (8,621,806) developed by four co-inventors for a "composite joist floor system." The co-inventors are Glenn Wayne Studebaker, Norfolk, Nev., David Lee Samuelson, Madison, Nev., Lionel Edward Dayton, Norfolk, Nev., and Richard Lukes, Decorah, Iowa.
The patent application was filed on February 19, 2010. According to the application, the composite joist floor system includes joists supported by supporting members. Corrugated steel decking is positioned over the joists such that the corrugations are substantially perpendicular to the joists. Self-drilling, self-tapping, stand-off screws are spaced along the length of the joist, aligned with the deck corrugations. These stand-off screws provide the required shear transfer between the joist and concrete slab to form a composite floor system. The placed concrete encapsulates the upper non-threaded shank portions of the stand-off screws and the end of the joists. After the concrete has cured, the resultant system comprised of steel joists, steel decking, stand-off screws, and concrete, act together to form a composite system with greater load carrying capacity and less vertical deflection. The stand-off screws connect the joist upper chords to the concrete slab allowing the joist and concrete slab to act as a unit, by transferring shear between the two joined components.