Abstract: A prefabricated spatial structure includes rods which are rectilinear tubes having a circular section and closed at each end by a cap which is joined to the tube by means of an annular weld or any other convention system and which has a hole concentric with the axis of the rod. The circular head of a special bolt is housed in the interior part of the cap. The bolt includes two threaded bodies having different diameters and opposite threading directions, the threaded body closest to the head having a smaller diameter than the diameter of the hole of the cap. The other threaded body is situated at the end of the bolt and has threads identical to that of the holes made in a node. The difference in diameters of the bodies is determined by a step which forms a flat or truncated resting surface coaxial with the axis of the bolt. The bolt is provided with a threaded nut which is coupled to the threaded body having the greater diameter.