Abstract
In the previous investigation, it has been shown that strength of the joint decreased as a result of stress concentrations in flange portions of a square-section tube to which gusset plates were welded directly, loaded in their plane by tension forces on the ends. The results of series of tests on the joints reinforced with triangular stiffeners which are made of various sizes, or on the joints reinforced with seat angles which could be often seen up in present-day construction, are presented in this report to compare with each other's. By using the triangular stiffeners the strength in the joint was improved as a result of preventing the "Platten-like" deformations in flange portions of the tube. Therefore maximum load was ca. 1.5〜2.0 times as large as that of unstiffened. It is significant, however, that the maximum load was not increased, in the case of the joint reinforced with the angles, because under tension load weld cracks began at points of contact between the gusset plate and web of the tube at a lower load, and because under compression load the web portions buckled locally. A simple theory described give adequate explanation of experimental behaviors, i.e., the strength of the joints reinfouced with the stiffeners may be computed under the tension load only by resistance of the qusset plates, and under the compression load only by local buckling resistance in the web portions of the tube themselves.
