Design and fabrication of welded high-strength hollow section joints

Established manufacturing facilities allow the precise cutting of the contour of truss members placed on hollow section chords as round or rectangular hollow sections. When calculating the load-bearing capacity of hollow section joints according to DIN EN 1993-1-8 and ISO 14346, fully load-bearing welded connections are assumed. Influences on the load-bearing capacity of hollow section joints include the weld geometry, the steel grades of the chords and braces, and the filler materials and welding processes used. Various failure modes require that the joint show sufficient ductility. A plastic rearrangement capacity must be ensured. As the yield strength increases, it becomes more difficult to meet this requirement. Reasons for this may be a reduction in strength or embrittlement of the weld areas. To avoid premature failure within the heat-affected zone, the welded connections must be properly and professionally executed. Another article in this issue of Stahlbau deals with the static load-bearing capacity of welded high-strength hollow section joints. An overview is given of the current AiF-FOSTA research projects in this area. The following article explains the design and execution of welded connections on high-strength hollow section joints, First, the design rules for welded connections in the new edition of EN 1993-1-8 are discussed. This is followed by explanations of the execution of welded hollow section joints, including cutting, flank preparation and welding. Based on this, the development of a test program for the investigation of brace-to-chord connections is presented and the influence of the processing parameters on the mechanical properties of the welds and the heat-affected zone is discussed.