Abstract
A series of tests on the truss joints for tubular roof trusses have been continued, and this report supplies the results of the test in which the dimensions of the members meeting in the joints and the welding conditions were varied into some different cases. Though the manner of failure, of course, differed each other with the dimensions and combinations of all members meeting in the joints, the most dominant type in the manner of failure was the local deformations in the walls of chord members. Thus the magnitude of these local deformations and the strength of the joints were found to be affected greatly by the wall-thickness of the chod members. The other truss joints of which the local deformations in the walls of the chord members were not the causes of their failure failed as a result of tearing tension diagonals or local buckling of compression diagonals. The strength of the joints which failed in these two manners were both related, more or less, to the net section strength of the diagonal members. Because the fracture in the welds seldom occurred in spite of the fact that the end of the diagonals were prepared by sawing in one (or two) continuous operation, it was inferred that the ends of tubes which were to be welded directly to the surfaces of the other tubes could be cut in the form of plane so long as the root openings were maintained within 3 to 4mm.
