Evaluation of reinforced connections between steel beams and box columns

This study elucidates the cyclic behaviour of connection between a steel beam and a welded box column. Distribution of stresses at the joint between beam and box column inherently differ from those of the joint to the H-shaped column, as confirmed by finite element analysis. Six large-scale specimens were designed. A specimen with an unreinforced connection was tested initially to clarify its performance. The test results indicated that brittle fracture occurs at the beam flange complete joint penetration weld and in the weld access hole region, because the stresses are concentrated in these regions. Nevertheless, specimens reinforced by vertical rib plates on beam flanges achieve an inelastic rotation of more than 3% rad prior to failure by forming a plastic hinge in the beam away from the beam-to-column interface. The test results also revealed that welding diaphragm inside the box column is crucial during the welding process to the integrity of the connection, ensuring that beam forces are transferred to the connection.