Flexural behaviour of wire arc additively manufactured tubular sections

Wire arc additive manufacturing (WAAM) is a promising metal 3D printing technique in the construction industry for its ability to produce large and complex-shaped elements, with reasonable printing accuracy, time and costs. There is currently, however, a lack of fundamental test data on the structural performance of WAAM elements. To address this, an experimental study into the cross-sectional behavior of WAAM tubular beams has been conducted and is presented herein. A total of 14 stainless steel square, rectangular and irregular hollow sections, spanning over all cross-section classes of EN 1993-1-4 and AISC 370, were tested in four-point bending. 3D laser scanning, silicone casting and Archimedes' measurements were employed to collectively determine the as-built geometry and local geometric imperfections of the test specimens, while digital image correlation (DIC) was used to monitor the deformation responses of the specimens during testing. The full moment-curvature histories and key experimental results are presented and discussed. Similar cross-sectional behavior to that of equivalent, conventionally manufactured sections was observed, with the more slender cross-sections showing increased susceptibility to local buckling. However, owing to the inherent geometric variability of WAAM, the tested 3D printed beams exhibited more variable flexural capacities between the repeat specimens than is generally displayed by conventionally produced stainless steel sections. Finally, the test results were used to assess the applicability of current crosssection design provisions in the European (EN 1993-1-4) and American (AISC 370) structural design specifications, as well as the continuous strength method (CSM), to WAAM stainless steel tubular beams.

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