Experimental and numerical investigations on built-up cold-formed steel beams using resistance spot welding

Abstract

The lightweight steel structural systems such as trusses or built-up beams, consisting of thin gage steel elements, are highly efficient and have the advantages in ease of handling and construction. The major concern relates to the joining technique between each part of the element. Commonly, the connection between thin-walled elements is performed by self-drilling screws but the quantity of time and manpower necessary for a large number of connections, demands an improved solution. Conventional welding technology is not appropriate for connecting thin sheets, such those of 0.4 mm–1.0 mm, to thicker ones of 1.0 mm–3.5 mm. The electric resistance spot or seam welding are widely used in the automotive industry to connect thin-to-thin metal materials. These technologies can be applied in case of thin-walled cold-formed construction, too. The paper presents a study on a new technical solution for lightweight cold-formed steel beams made of corrugated sheet web and built-up steel profiles for the flanges, connected by spot welding. Starting from the investigations on simple lap joint specimens tested under tensile-shear loading for various thicknesses combinations, the research concerns also metallographic aspects and investigates the response of the full-scale beams subjected to bending. Based on the obtained results, the study intends to demonstrate the feasibility and advantages of this solution compared to self-drilling screw solution. Particularly, besides the structural performance, the spot-welding solution increase significantly the work productivity and enables for automated fabrication in order to develop the mass production of these types of beams.