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• An innovative double and zigzag castellated steel beam design was developed and experimentally tested. • For double castellated beams reducing the number of web openings with a 52° cutting angle enhanced load capacity by up to 51% and reduced deflection by 59.7% compared with solid beam. • In contrast, zigzag layouts showed 10-19% lower capacities and two main failure modes: sudden web-post buckling at sharp corners and progressive tearing at the opening edges. • Finite element analysis validated experimental results with high accuracy. Castellated steel beams represent a unique and interesting solution in the field of structural steel, which allows material distribution through web openings. However, these changes change the load transfer function and failure mode. In this study, two novel hot-rolled IPE section forms, namely Double Castellated Beams (DCB) and Zigzag Castellated Beams (ZCB), are investigated in terms of strength and stiffness in supported conditions. The structural behavior of these innovative double and zigzag castellated steel sections is examined experimentally and numerically on twelve specimens, including a solid beam and traditional castellated beam. Three critical parameters, namely the number of openings, cutting angles (45°, 52°, and 58°), and castellation types, were investigated. The influence of these parameters on the stiffening, ultimate load-carrying capacity, and failure modes are examined. It is concluded that the double-castellated beam with a 52° cutting angle and a minimum number of openings will provide the optimal performance, demonstrating up to 51% higher load capacity than solid beams where reasonable stiffness and ductility can be achieved. The dominant mode of failure for these beams was the ductile development of a Vierendeel mechanism. In contrast, zigzag layouts showed 10-19% lower capacities and two main failure modes: sudden web-post buckling at sharp corners and progressive tearing at the opening edges. Finite element (FE) models of the tested specimens were created, which took into account material and geometric nonlinearities and actual measurements of geometric imperfections. Numerical models showed acceptable agreement with experimental results for ultimate loading, deflection behavior, and failure modes.
Naji et al. (Tue,) studied this question.