Buckling behaviour and design of DED-Arc high strength steel circular hollow sections

Wire-Arc Directed Energy Deposition (DED-Arc) or Wire Arc Additive Manufacturing (WAAM) is a metal 3D printing method offering the ability to produce large-scale structural components with complex geometries in an efficient and cost-effective manner. To date, only a limited number of experimental studies on the structural behaviour of slender DED-Arc hollow sections have been conducted. To fill this gap, new experimental evidence on the behaviour of DED-Arc shell structures is thus reported. A comprehensive experimental programme investigating the local buckling response of DED-Arc high strength steel circular hollow sections (CHS) over a wide range of cross-sectional slendernesses has been conducted. In total, twelve DED-Arc CHS stub columns with a series of diameter-to-thickness ratios were produced using ER120S-G wire. The undulating as-built geometry and the initial geometric imperfections of the stub columns were captured using 3D laser scanning. During the stub column tests, the deformation fields were captured by means of digital image correlation. In the present paper, following the description of the specimen production, the experimental programme is described, the test results are analysed and the applicability of the current Eurocode 3 rules to the design of DED-Arc CHS is assessed by comparing the test results with the EN 1993-1-1 and EN 1993-1-6 design provisions. The test results show that the structural behaviour of DED-Arc CHS is similar to that of conventionally-produced (i.e. cold-formed and hot-rolled) steel CHS. Both EN 1993-1-1 and EN 1993-1-6 yield safe-sided resistance predictions, with the latter being more accurate since it incorporates the influences of both the fabrication quality and of the initial geometric imperfections. • Experimental study on local buckling behaviour of DED-Arc high strength steel CHS. • 3D laser scanning and characterisation of local imperfection patterns of DED-Arc CHS. • Coupon tests and microstructure characterisation of DED-Arc high strength steel. • Applicability of EN 1993-1-1 and EN 1993-1-6 provisions assessed using test data.