Double top chord

Claim 1

In a composite action steel and concrete floor system wherein a plurality of steel joists span horizontally and in spaced parallel relationship between spaced support members, each said steel joist including a top chord, a bottom chord and an intermediate web vertically extending between said top and bottom chords, composite action being achieved by complete embedment of each top chord in said cured concrete, and in which said joists are subject to construction loads during a non-composite state of construction of said floor system due to their own weight, construction live loads and wet concrete, the improvement wherein each top chord of each joist comprises a pair of identical, longitudinally continuous, symmetrical, oppositely-positioned S shaped members extending in a parallel relationship for the length of the respective joist, said S shaped members being in mirror relation to one another with the right-hand one appearing in cross section in a regular upright S form and the left-hand one in reverse S Form and being transversely spaced apart symmetrically relative to said web providing a joist having symmetry about a vertical axis passing through said web, whereby the ability of said joists to withstand said construction loads during said non-composite steps is substantially increased.