Seismic performance of blind-bolted joints for square steel tube columns under bending-shear

Abstract In this study, a plug-in plate blind-bolted joint and double-splint blind-bolted joint are proposed for square steel tube columns. The seismic performance of joints under bending-shear combination was studied via experiments and finite element simulations. Four test specimens of plug-in plate blind-bolted joint and double-splint blind-bolted joint were studied by varying the numbers of bolts used in the connection. Additionally, eleven joints with different thicknesses of the plug-in plate, the double-splint, and the column wall were compared via finite element simulation. The strength of the test specimens increased till the loading was stopped at 0.05 rad. This suggests that the specimens had good ductility and rotation ability. The effect of the number of bolts, thickness of the plug-in plate and double-splint on the rotational stiffness, slip resistance, ductility performance, energy dissipation capacity, ultimate load-bearing capacity, and yielding mechanism of the joint were analyzed. Additionally, simplified equations were derived for slip resistance and yield strength of the joints. The values obtained using these equations agreed well with that of the experiment and finite element analysis. Furthermore, four frames with the plug-in plate blind-bolted joint and double-splint blind-bolted joint for square steel tube columns were subjected to cyclic loads. Their seismic performance was found to be better than that of the frame without the column joint. The proposed blind-bolted joints can be used for splicing a column at mid-height.