Experimental study on slotted rectangular and square hollow structural section (HSS) tension connections

An experimental study has been carried out on slotted hollow structural section (HSS) connections with and without welding at the end of the gusset plate. A total of 30 slotted square and rectangular HSS specimens, with 16 different connection configurations, were investigated for effects of weld length ratio, slot orientation, gusset plate thickness, slot opening length, and end welding. Experimental results show that the net section efficiency of the specimen with no end welding was greater than unity for a weld length ratio (L/w), where L is weld length and w is the circumferenctial distance between the longitudinal welds, as low as 0.8, and full net section efficiency was achieved with L/w ratio as low as 0.76 for a square HSS specimen with end welding. These results support findings from other research that show provisions to account for the effect of shear lag in slotted HSS connections are overly conservative in both Canadian and American design standards. Recommendations are provided to improve on provisions to account for shear lag in the Canadian design standard.