抄録
The test results on the gusset-tube joints under compressive and tensile load acting in the direction of tube axis are presented in this report. When the compressive loads were applied to the joints having single gusset plate, large local deformations of the cross section at the tubes were produced in the vicinity of welding lines. This resulted in the unstable state of the joints. No failure was observed in the weld zone itself. It was concluded that the weld length was one of the factors influencing the strength of the joints, not as a quantity which affected the strength of the welds in the joints, but as a quantity which affected the local deformation of the walls of the tubes. For the joints loaded in tension, cracks began at the points of contact of gusset ends with the tube slots or at the portions along the weld lines. Joint efficiencies were not more than 85 to 90% even for the joints which had sufficiently long weld length, probably due to the flaw in the welds at the gusset ends. Minimum weld length l required to obtain the efficiency of 85% could be determined by l=1.15D, where D was the outer diameter of the tubes. The joints which had double gussets (U-shaped gussets) were torn at the cross sections of the tubes just below the weld line accompanying large opening deformations of gussets under tensile load. It was inferred that the half segments of the tubes divided by gusset plates were loaded in eccentric tension for the joints of double gussets type. The strength of these joints was lower than that of the joints having single gussets.
