Computer floor structure

A generally rectangular floor panel adapted to be supported at its corners comprising a body of nonflammable concrete-like material having substantial compressive strength, low tensile strength and a low co-efficient of thermal transfer, said body having a planar upper surface and a lower surface, a grid of reinforcing elements embedded in said body substantially adjacent said lower surface arranged in arrays of elements which divide said panel into a plurality of reinforcing element bounded zones, said body being formed with a plurality of cavities within said zones which are open to said lower surface and are substantially uniformly sloped inward and upward toward said upper surface at an angle with respect to said lower surface substantially no greater than 45.degree., said cavities terminating at a location spaced from said upper surface, said body providing a substantially homogeneous upper portion above said cavities of substantially uniform thickness and integral depending walls located around said cavities and extending from said upper portion to said lower surface, said upper portion being free of reinforcing elements and being supported substantially throughout its lower extremity by said wall portions, said wall portions being sufficiently wide adjacent to said upper portion to support substantially the entire lower extremity of said upper portion, said walls extending downwardly with substantially uniformly decreasing width to said lower surface and being free of reinforcing elements except substantially adjacent to said lower surface, said body and grid cooperating so that loads applied to said upper surface produce compressive stresses in said concrete-like material without any significant tensile stresses and produce tensile stresses in said elements of said grid without any significant compressive stresses, the strength of said panel with respect to said loads on said upper surface being substantially the same as a similar panel without said cavities.