Composite floor system

Claim 1

A composite concrete floor system comprising a plurality of metal joists, said joists having a top chord, a bottom chord and a web comprising tension and compression members in the space between the top and bottom chords and secured to said top and bottom chords, the top of said web being secured to the lower surface of sid top chord, said top chord having two horizontal legs and a vertical leg having a lower end and an upper end, deformations formed in the vertical leg between the upper and lower ends thereof such that there is no decrease in the height of the vertical leg along its length, said deformations extending laterally outwardly from said vertical leg, metal decking material supported between the horizontal legs of the top chords of adjacent joists, a concrete slab formed over the metal decking and the top of the joist in which the top chord is embedded with the deformations extending into said concrete slab, reinforcing mesh embedded in said concrete slab such that axial forces on said top chord which cause said deformations to act as wedges tending to split the concrete slab are counteracted by transverse restoring forces created by the reinforcing mesh.