Abstract: A structural element for metal structural work is formed, in the manner of a tube, by a pair of half-shell fellow sections, arranged with their concavities opposed and connected together in a discrete manner along their long sides, such as to guarantee a much higher torsional rigidity than that provided by corresponding open sections.The structures which can be obtained with structural elements of this type include flat and three-dimensional girders, particularly in the form of supports for electric lines, of which the stringers are formed with said elements in order to provide high torsional rigidity.