Feasibility of slotted end connections improved with thicker sections in tension: Experimental and numerical investigation

Abstract Gusset plate slotted end connections are effective and convenient techniques for connecting tubular members in building structures. A net section crack is the dominant failure mode found in conventional slotted end connections unless strengthening measures are adopted. The improved connection involves a thick-walled circular hollow section (CHS) set at both ends of the member to increase the area of the net section. A series of laboratory tests and associated numerical models were conducted to investigate the mechanical performance of the improved slotted end connection under axial tensile loading. The load-displacement relationship, stress distribution characteristics, and typical failure modes are all incorporated and discussed. Different from tear-out failure or net section crack failure in a conventional connection, the improved connection shows gross section cracks after experiencing extensive gross section yielding. The improved connection enables the length of the fillet weld (LW) to be greatly reduced without causing a reduction in the load-bearing capacity. With the gradual increase in the length of the fillet weld (LW = 60, 90, and 120 mm), the axial load-bearing capacity of the improved connection is approximately 34.6%, 15.8%, and 4.9% higher than that of the conventional connection, respectively. From the validated FE analysis, the local stress concentration near the slot end can be reduced by approximately 50%, and the shear lag has little effect on the strength of the net section. The load-bearing capacity, ductility, and failure modes of the improved connection show better performance than those of the conventional connection.