Shear Behavior of Panel Zones in Steel Beam-to-Column Connections with Unequal Depth of Outer Annular Stiffener

This paper presents an experimental investigation of the shear behavior of steel beam-to-column connections with unequal depth of outer annular stiffener. The depth-to-thickness ratio (D:t) of the hollow structural section (HSS) column, the beam depth ratio (Db2:Db1), and two sizes of outer annular stiffener are considered. This test involves seven cruciform connections subjected to lateral cyclic loading with vertical displacements imposed at the end of beams. The failure modes, hysteretic performance, strength and stiffness degradation, shear deformation, and energy dissipation of panel zone are estimated. The experimental results indicated that the whole panel exhibited large hysteretic loops, excellent ductility, and energy dissipating capacity. Due to the effect of the beam depth ratio, the tested specimens formed two types of failure modes: shear buckling of the whole panel and shear buckling of the primary panel at the column web between two beams.