Bending resistance of welded hybrid slender I-section beams

Hybrid steel beams, in which plates of different steel grades are combined – with higher-strength steel applied in the flanges – offer an efficient solution for increasing load-carrying capacity while optimizing material use and cost efficiency. The research thoroughly investigates the bending behavior of I-section hybrid beams across a wide range of geometric configurations. The primary objective of the paper is to address the lack of analytical methods in current literature for determining the resistance of cross-sections featuring Class 4 flanges and webs. The applicability of existing design proposals is rigorously assessed through detailed numerical analyses. Numerical simulations are performed, encompassing a broad spectrum of slenderness and hybrid ratios. The simulations are based on a sophisticated numerical model that has been validated with previous laboratory experimental data (from the literature). The numerical results obtained are then used to evaluate the accuracy of various analytical formulas for the bending resistance calculation. Furthermore, the study specifies the necessary partial factor ( γ M⁎ ) for the different formulas. Ultimately, this research aims to analyze and describe the behavior of slender beams under bending, which could lead to more reliable and economical design solutions for hybrid steel structures in the future. • Bending behavior of hybrid I-section beams is investigated numerically • Wide range of slenderness and hybrid ratios is analysed • Cross-sections with Class 4 web are addressed with no existing analytical methods • Accuracy of current design formulas is systematically evaluated