Structural behavior of built-up I-shaped cold-formed steel beams with edge-stiffened holes, unstiffened holes, plain webs, and batten reinforcement

• Web perforations reduced beam capacity by 6.3-10.1 %. • Edge stiffeners increased capacity by 6-17 %. • Battens increased capacity of unstiffened holes by 5-9 %. • Stiffeners plus battens improved capacity by 9-14 %. Perforated cold-formed steel (PCFS) back-to-back channel beams are increasingly gaining popularity in the building sector due to their numerous advantages and economic benefits. Notably, their lightweight nature allows for easier handling and installation, while the holes in PCFS beams facilitate the accommodation of utilities such as electrical and plumbing installations. In this study, a geometrically and materially nonlinear finite element model (FEM) was developed and validated using experimental data from existing literature. The validation results indicated a strong correlation, with the ratios of FEM and Direct Strength Method (DSM) predictions to experimental outcomes being 1.007 and 0.945, respectively. This demonstrates a significant agreement among experimental data, FEM analysis, and moment capacity estimations based on American Iron and Steel Institute (AISI) Standards, although AISI predictions were found to underestimate moment capacities by approximately 5.5 %. Following model validation, an extensive parametric study involving 192 FEM simulations was conducted to evaluate the influence of hole size, hole geometry, edge stiffeners, and batten reinforcements on the moment-carrying capacity of built-up I-shaped CFS beams. The findings indicate that, in comparison with beams having plain webs, the presence of web openings leads to a reduction in moment capacity of approximately 10 %, 9 %, 9 %, and 6 % for circular, slotted, square, and rectangular holes, respectively. Furthermore, the results demonstrate that the inclusion of stiffeners around web openings, together with batten reinforcement, markedly improves the structural performance of PCFS built-up beams. In particular, the maximum enhancement in moment capacity of beams with batten reinforcement and edge-stiffened holes, relative to those with unstiffened holes, is about 9 %, 10 %, 13 %, and 14 % for circular, rectangular, square, and slotted holes, respectively. Overall, the findings offer valuable insights into the structural behavior of perforated built-up CFS beams and emphasize the effectiveness of web hole stiffening and batten reinforcement strategies in mitigating strength reductions caused by web perforations.