The present invention relates to a truss structure for use in a roofing and the like of a building.
As a space truss structure which can shorten the term for completion of work by facilitating the connection of its chord members, a conventional truss structure is disclosed in JPA Laid-Open No. 60-89744. A connection member is provided on one surface of which a connection tube for connecting chord members is erected, and on the other surface of which a rib for connecting diagonal chord members is mounted, whereby chord members each having a connecting part on the end thereof are connected thereto via washers which may be in any numbers. Further, JPA Laid-Open No. 5-311765 discloses a flat metal square column pipe member having a concave cross-section fitting member on both ends thereof formed by press or roll working, and wherein the concave cross-section fitting part is provided with a long narrow opening for fitting which is pierced therethrough. Still further, a double pipe type truss beam which integrates an upper chord member and a lower chord member formed of a pipe, and a web member is disclosed in JPA Laid-Open No. 7-180217. Still further, JPA Laid-Open No. 61-100704 discloses a connection structure for a truss joint which is comprised of joining diagonal pipe members via a cross gausset plate to an M-shaped, H-shaped chord members or to a vertical pipe member, wherein a backup member outside the truss plane of the gausset plate is omitted such that the bore of the pipe between a flange and a web of the chord member is effectively utilized.
As mentioned above, various efforts have been made in order to facilitate the connection of the chord members and shorten the term for completion of work. Also, it is known to flatten the connection edge of the chord member by compression pressing to this effect. In this conventional structure, however, existence of a free plastic deformation part, which is elliptic and extends between the flat surface provided by compression pressing and the complete round section of a parent pipe member cannot be avoided. This long and narrow free plastic deformation part adjoining the connection end structure flattened by compression according to the conventional method is not only unnecessary but also disadvantageous in the truss structure because the size of the parent plate for connecting the chord member using a bolt thereto becomes inevitably large. Provision of such a large sized parent plate has been a cause to increase the size of its joint structure, thereby decreasing its rigidity, and increasing the cost of manufacture.