Effect of Residual Stresses in Welded I‐Members with Plasma‐, Flame‐Cut and Hot‐Rolled Flanges on the Lateral Torsional Buckling

Abstract The lateral‐torsional buckling of a steel welded I‐section beam is highly affected by the residual stress distribution, in particular at the flange ends. These distributions are impacted by the fabrication process, such as flame‐ or plasma‐cuts performed at the flange ends. However, few studies compared the impact of these three cases on residual stresses and stability of welded I‐members. For this reason, residual stress measurements have been performed on 9 welded I‐section specimens made of S355 steel to assess the impact of these fabrication processes. 3 series of 3 specimens were built‐up with the same dimensions but varying the type of flange: flame‐cut, plasma‐cut and hot‐rolled. Experimental results highlight a clear effect of the flange fabrication process on the residual stresses at the flange ends, and a small effect on the flange compressive stresses. The experimental distributions are then employed to perform a numerical sensitivity study on welded I‐section beams under constant bending moment. The results demonstrate a significant favorable effect of the plasma‐ and flame‐cuts on the lateral‐torsional buckling resistance when compared to hot‐rolled flanges.