EXPERIMENTAL INVESTIGATION OF ALUMINUM WELDED LATTICE GIRDERS

Šemso Kalač; Naja Zejnelagić; Đorđe Đuričić; Duško Lučić

doi:10.5937/jaes0-51073

Šemso Kalač Faculty of polytehnics, University Donja Gorica, Podgorica, Montenegro
Naja Zejnelagić Faculty of civil engineering, University of Montenegro, Podgorica, Montenegro
Đorđe Đuričić College of applied sciences Užice, Western Serbia Academy of applied studies, Užice, Serbia
Duško Lučić Faculty of civil engineering, University of Montenegro, Podgorica, Montenegro

DOI: https://doi.org/10.5937/jaes0-51073

Keywords: welded aluminum joints, heat-affected zone, experimental investigation, lattice girder, square hollow section profiles, circular hollow section profiles

Abstract

Aluminum and its alloys are valued for their corrosion resistance, lightweight and versatile functionality within extruded profiles. However, the integration of aluminum into welded truss systems is complicated due to the formation of heat-affected zones (HAZs). In these zones, as a result of the softening effect, the reduction of load-bearing capacity is up to 50%. This complicates the design of welded joints, introducing a significant challenge to the seamless application of aluminum in such structural frameworks. The lack of specific rules for welded aluminum joints in the regulatory standard EN 1999-1-1 (EC 9) contributes to the issue. Consequently, engineers decided to use EN 1993-1-8 (EC 3), a standard not specially designed for aluminum applications, but for steel. This approach obliviously results in a conservative design process that ignores all of the advantages that aluminum alloys provide. In response to this discrepancy, our study examines the behaviour of welded joints within lattice girders, crafted from the EN AW6082 T6 alloy. This is the most widely used aluminum alloy for structures, which has yielding strength values up to those of steel S235. It is known that due to material softening during the welding process, the yield strength in the heat-affected zone (HAZ) of this alloy might drop by up to 50%. All tested lattice girders have the same chord members, which are square hollow section (SHS) 100x5 profiles. The brace members' sizes and shapes have been variated in order to perform the parametric investigation. The three trusses were built using brace members from square hollow section profiles (SHS) with widths of forty, fifty, and sixty mm; the remaining three trusses were built using braces from circular hollow section (CHS) profiles with diameters of forty, fifty, and sixty millimeters. The extensive experimental investigation combined with parametric analysis indicates complex load-bearing behavior depending on cross-section types and size. These results highlight the complex structural behaviour of aluminum lattice girders due to the peculiarity mentioned above which occurs in aluminum due to the heat input as a result of welding.

References

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