Use of The Aluminum Alloy 3 Ways Spigot Truss The aluminum alloy 3 ways spigot truss is mainly used to connect the beams and columns in three directions on the Arch Roof truss. The surface is sprayed with black plastic. This aluminum alloy 3 ways spigot truss different from the Corner Box in that it can only be used in the middle of the beam to connect small columns     Advantage of...