Fracture Mechanism And Test Of Joints Of H-style Beam-square Steel Tubular Column

Using an elliptical yield model together with an elliptical fracture model suggested by WanzhenWang, the joint of H-style beam-square steel tubular column was numerical simulated andanalyzed. The modified coefficient of elliptical fracture model was obtained by equivalentlycalculating the effects of residual stress and flaws that was compared the result with test.Using the elliptical fracture model with equivalently calculating the effects of residual stress anddisfigurement for evaluation, and reaching0.03rad of the plastic rotation that required of the FEMAinterim guidelines for aim, the slot holes and horizontal haunch at beam flanges on failure mode ofjoints of H-style steel beam-square steel tubular column were put forward. And the effect of diameterd fand lengthd sof slot holes and the distance a between weakened section and side of column on stressbehavior were discussed.According to the results of finite element analysis, low-cycle reversed loading tests wereperformed on six joints of H-style beam-square steel tubular column. The experimental resultsindicate that the conventional joint of H-style steel beam-square steel tubular column brittlefractures at beam flanges butt weld and the plastic rotation does not meet with the requirement ofthe FEMA interim guidelines. The stress concentration at beam flange butt weld of the joints of H-style steel beam-square steel tubular column is markedly mitigated by means of slot holes andhorizontal haunch at beam flanges, and a plastic hinge formed at the reduced beam section. Theplastic rotation reached0.03rad and meet with the requirement of the FEMA interim guidelines,and the loading capacity decrease within15%compared with that of the conventional joint.Combineding the results from experiment and finite element analysis, and considering theplastic deformation ability and loading capacity of the joints, and the value of slot holes at beamflanges were suggested.