Local and distortional buckling of WAAM-strengthened hot-rolled steel I-sections under axial compression

Wire arc additive manufacturing (WAAM) is an advanced metal additive manufacturing technology, suitable for producing large-scale metal components. This technique holds significant potential in hybrid construction, such as reinforcing I-sections, where stiffeners can be added to the flange tips to enhance the load-carrying capacity. However, the addition of such stiffeners changes the residual stress pattern and introduces the possibility of distortional buckling, both of which require the development of new structural design provisions. To address this, an experimental investigation into the local and distortional buckling response of hot-rolled steel I-section stub columns strengthened by WAAM has been undertaken and is presented in this paper. The test specimens, with different WAAM stiffener heights, were loaded under axial compression to study their cross-sectional load-carrying capacity. Finite element (FE) models were then developed to replicate the buckling behaviour of the examined cross-sections. Following validation against the experimental data, parametric studies to investigate the structural response of WAAM-strengthened I-sections of various geometries were conducted. Based on the obtained numerical and experimental results, cross-section classification limits and local/distortional buckling curves, following both the effective width method (EWM) and the direct strength method (DSM) were established, including a revised distortional buckling curve for the modified EC3 approach. Reliability analysis was performed to determine suitable partial factors.