Experimental Assessment of the Behavior of Tubular Truss Girder Joints Fabricated with Laser Cutting Technology

Abstract

Directly welded truss girder joints result in high-stress development on the tube wall, which leads to increased chord thicknesses, requires extra welding, and presents detailing difficulties. Laser cutting technology (LCT) allows us to make precise cuts and pass through the truss members, welding the connection on the two sides. This can reduce geometrical imperfections, and, as a result, it increases joint strength. This paper presents truss girder joints developed with LCT that can develop higher resistance to static gravity loads with respect to conventional connections thanks to the pass-through solution. An extensive experimental campaign (31 specimens) has been carried out involving the monotonic gravity loading of several truss specimens to simulate their in-service conditions. Different truss typologies are tested (Warren and Pratt) using circular and square hollow section profiles, at different scales (full-scale and small-scale). The results showed that Warren-type structures with LCT connection solutions had a 20% higher strength with respect to the equivalent structures with directly welded joints. Furthermore, the correlation between the different failure modes and joint parameters (e.g., angles and distance between brace members) has been discussed.