Influence of Web Opening Geometry on the Structural Performance of Castellated Composite Beams

International Journal of Civil Engineering

© 2025 by SSRG - IJCE Journal

Volume 12 Issue 11

Year of Publication : 2025

Authors : Riza Suwondo, Adelia Nataadmadja, Mohammed Altaee

10.14445/23488352/IJCE-V12I11P107

How to Cite?

Riza Suwondo, Adelia Nataadmadja, Mohammed Altaee, "Influence of Web Opening Geometry on the Structural Performance of Castellated Composite Beams," SSRG International Journal of Civil Engineering, vol. 12,  no. 11, pp. 89-97, 2025. Crossref, https://doi.org/10.14445/23488352/IJCE-V12I11P107

Abstract:

Castellated composite beams comprise a steel-castellated section and a concrete slab. Modern floor systems increasingly employ these beams owing to their high strength-to-weight ratio and versatility in service accommodation through web openings. Despite their advantages, web openings lead to significant, intricate, and complex local and global behaviors pertaining to strength and serviceability. This study focuses on the geometrical configuration of web openings, specifically the height, width, and spacing, and how these attributes define the structural behaviour of castellated composite beams. ETABS was used to create the finite element models, and design checks were carried out according to the provisions delineated in the AISC Design Guide 31. In the parametric analysis, the opening height (220-280 mm), width (240-300 mm), and spacing (270-330 mm) were varied. An assessment was performed on the overall behaviour in terms of ultimate strength, deflection, and local failure modes. The results show that the opening height has the most significant impact on the overall performance; increasing the height enhances the top-tee strength and reduces deflection, improving both the load-carrying capacity and stiffness. In contrast, the opening width and spacing mainly affect the local web-post stability. Wider or closely spaced openings increase the susceptibility to web-post buckling, whereas larger spacing restores tee interaction as the governing failure mode. Deflection remained within the serviceability limits, except for the smallest opening height. These findings demonstrate that an optimised combination of opening geometries can enhance structural efficiency while maintaining serviceability. This study offers practical guidance for designing castellated composite beams and contributes to the development of safer, lighter, and more sustainable long-span floor systems.

Keywords:

Castellated Composite Beams, Web Opening Geometry, Structural Performance, Serviceability, Web-Post Buckling, AISC Design Guide 31.

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