Structural bar including: - an extruded profile defining a normal section surface, a horizontal loading direction along said a normal section surface and a vertical loading direction along said a normal section surface perpendicular to said horizontal loading direction and said profile comprising: - a core arranged in a central position at the intersection of said directions (1a, 1b), - a plurality of arms each including: - a radial segment radially connected to said core perpendicular each to each other and each oriented at 45° with respect to the horizontal load direction and/or the vertical load direction, and - a tangential segment perpendicularly connected to said radial segment and configured, when a single load is applied on the extruded profile along said horizontal load direction and/or said vertical load direction, to simultaneously support together the load to distribute the stress resulting from the load as a shear stress; - a joining device for extruded profiles comprising a support defining a flat connection surface suitable to allow the interface with said extruded profile, a second horizontal load direction along said connection surface and a second vertical load direction along said connection surface perpendicular to said second horizontal load direction and said device comprising a plurality of teeth protruding from said support perpendicularly to said connection surface; and characterized in that - said teeth form with part of said support at least two convex grooves extending respectively along said second horizontal load direction and along said second vertical load direction, - said device and said extruded profile are connected to each other in such a way that said normal section surface and said connection surface are opposite each other and the horizontal and vertical load directions are respectively aligned with the second horizontal and vertical load directions. - an extruded profile defining a normal section surface, a horizontal loading direction along said a normal section surface and a vertical loading direction along said a normal section surface perpendicular to said horizontal loading direction and said profile comprising: - a core arranged in a central position at the intersection of said directions (1a, 1b), - a plurality of arms each including: - a radial segment radially connected to said core perpendicular each to each other and each oriented at 45° with respect to the horizontal load direction and/or the vertical load direction, and - a tangential segment perpendicularly connected to said radial segment and configured, when a single load is applied on the extruded profile along said horizontal load direction and/or said vertical load direction, to simultaneously support together the load to distribute the stress resulting from the load as a shear stress; - a core arranged in a central position at the intersection of said directions (1a, 1b), - a plurality of arms each including: - a radial segment radially connected to said core perpendicular each to each other and each oriented at 45° with respect to the horizontal load direction and/or the vertical load direction, and - a tangential segment perpendicularly connected to said radial segment and configured, when a single load is applied on the extruded profile along said horizontal load direction and/or said vertical load direction, to simultaneously support together the load to distribute the stress resulting from the load as a shear stress; - a radial segment radially connected to said core perpendicular each to each other and each oriented at 45° with respect to the horizontal load direction and/or the vertical load direction, and - a tangential segment perpendicularly connected to said radial segment and configured, when a single load is applied on the extruded profile along said horizontal load direction and/or said vertical load direction, to simultaneously support together the load to distribute the stress resulting from the load as a shear stress; - a joining device for extruded profiles comprising a support defining a flat connection surface suitable to allow the interface with said extruded profile, a second horizontal load direction along said connection surface and a second vertical load direction along said connection surface perpendicular to said second horizontal load direction and said device comprising a plurality of teeth protruding from said support perpendicularly to said connection surface; - said teeth form with part of said support at least two convex grooves extending respectively along said second horizontal load direction and along said second vertical load direction, - said device and said extruded profile are connected to each other in such a way that said normal section surface and said connection surface are opposite each other and the horizontal and vertical load directions are respectively aligned with the second horizontal and vertical load directions.