Abstract: A composite beam or girder fabricated from a section of an "I" shaped rolled structural steel beam and a reinforced concrete slab is formed. The bottom flange and the web of the girder are a section of the "I" beam, the top "top flange" is the concrete slab. The steel section is obtained by cutting the web of the "I" beam in a zig-zag fashion into two similar sections, each having a flange and a sawtooth shaped web. Effective interconnection of the steel section and the reinforced concrete slab is achieved by anchor rods snugly fit into holes provided in the top part of the web.