Experimental evaluation of the effect of vertical connecting plates on panel zone shear stability

•The effect of vertical plates on panel zone stability is experimentally studied.•The vertical plate is found to be effective in minimizing panel zone shear buckling.•A modified equation on panel zone width-thickness ratio is proposed.•The axial load ratio is recommended to be restricted under a certain level.

Vertical connecting plates exist in the panel zones of spatial moment frames, which are used to link beam webs in the perpendicular direction. However, current provisions take no consideration of their effect on the panel zone shear stability. This paper aims to evaluate the effect of vertical connecting plates on panel zone shear stability through experimental studies on cruciform beam-to-column subassemblages with/without connecting plates under cyclic loading. The connecting plates are found to be effective in mitigating the shear buckling potential of the panel zone and thus improving the hysteresis behavior of slender panel zones. Based on current seismic provisions, a modified approach for evaluating the panel zone shear stability through its equivalent width-thickness ratio is proposed and proved to be appropriate and on the conservative side.