EFFECTS OF BEAM FLANGE WIDTH-TO-THICKNESS RATIO ON BEAM FLANGE FRACTURE CAUSED FROM SCALLOP ROOT

摘要

In steel building structures, the plastic rotation capacity of H-shaped beam welded to the column is affected by failure mode. When width-to-thickness ratio of beam flange (b/t) is large, local buckling of the beam flange governs the rotation capacity of the beam. On the other hand, when stocky beam section is used, fracture of the beam flange or weld at the stress concentration point of the beam end may occur. In this case, premature fracture of the beam flange or weld may occur before the local buckling of the beam flange, when the ductility and the toughness of the beam flange material is poor. In this study, four specimens with b/t = 5.0,6.7,8.3 and 10.0 are tested to investigate the boundary between the local buckling and the fracture of the beam flange. To clarify the failure mode, elasto-plastic PEA is also conducted. The results of this study are summarized as follows; 1) The failure mode of the specimen with b/t = 10.0 was the local buckling of beam flange. 2) The specimens with less b/t ratio were fractured caused by the ductile crack at the scallop root. 3) A specimen with b/t = 8.3 showed both failure mode and the maximum rotation capacity of the beam.