Effect of Stiffener Arrangements on the Performance of Castellated Beams under Static Load

Abstract Castellated beams are widely applied in modern structural systems because they provide reduced self-weight while maintaining a higher moment of inertia compared to solid I-sections. However, the presence of web openings can create stress concentrations and excessive deformation, which may compromise structural integrity. To address these weaknesses, stiffeners are commonly introduced, yet the most effective configuration remains uncertain. This study investigates the effect of stiffener arrangements on the structural behavior of a 1.7-meter-long cantilever castellated beam under static loading, using numerical simulation in SolidWorks 2023. The base profile is a modified IWF 150.100.6.9 steel section, modeled in five variations: (a) castellated beam without stiffener, (b) castellated beam with stiffeners at both ends, (c) castellated beam with three stiffeners positioned at both ends and midspan, (d) castellated beam with full stiffeners applied to all web openings, and (e) the original IWF profile prior to castellated modification. All models assume ASTM A36 steel with yield strength (fy) = 250 MPa and ultimate tensile strength (Fu) = 410 MPa. The results indicate that adding stiffeners enhances beam performance by reducing maximum displacement and lowering stress concentrations. Among the castellated beams, the model with three stiffeners provided the most effective balance, achieving lower stress and smaller deformation while maintaining material efficiency compared to the fully stiffened model. Comparison with the original IWF section further highlighted the trade-off between structural response and weight reduction. These findings confirm that proper stiffener placement is crucial to optimize castellated beams for cantilever applications.