A metal frame made up of a plurality of linear bars, which have a constant
cross section, are obtained by extrusion, and are joined to one another
by means of welding at structural nodes defined by jointing bodies
provided with pockets for housing the linear bars. The jointing bodies
have box type structures and are made up of the union of respective a
load-bearing element, which is obtained by extrusion and has a given
direction of extrusion, with a pair of plane closing metal sheets, which
are set perpendicular to the direction of extrusion and are welded to the
load-bearing element on opposite sides of the load-bearing element. The
load-bearing element may also be formed by the lateral union of a number
of simple elements, each of the simple elements being obtained directly
via extrusion and having a given direction of extrusion parallel to the
direction of extrusion of the other simple elements, and wherein the
simple elements are joined to one another laterally by mechanical slots.