Abstract: This disclosure relates to a floor construction comprising a concrete slab which is supported adjacent its edges of the slab. A plurality of cellular raceways are embedded in the slab, and at least one intermittently bottomless trench runs across the raceways. The trench is located along a line where the bending moment on the slab is substantially zero. The construction further comprises a plurality of post-tensioned tendons which extend across the slab, underneath the trench and between the raceways.

Abstract: A preset block assembly adapted for use with an underfloor electrical distribution system having one or more electrical conductors enclosed in elongated, laterally spaced cells. The block assembly includes a housing having a terminal portion that rests on the top wall of one of the cells and encloses an opening therein. In one embodiment, the housing has depending portions at each end thereof which seat in valleys defined by cells on each side of the central cell of a set of three. In another embodiment, the housing has only one depending portion which seats in the valley between a pair of the cells. In both embodiments, an outwardly extending sleeve on the side wall of the depending portion or portions extends into an opening in the side wall of the cell or cells adjacent to the cell underlying the terminal portion.

Abstract: Cellular floor panel assembly is made by precoating one or more metal sheets with anti-corrosion paint or similar protective covering, then forming a fluted first plate and a flat or fluted second plate and connecting the plates in face-to-face contact with rivet-like fasteners. In a preferred embodiment, the structure is formed of a single sheet folded to form upper and lower sections.