Mechanics-based analytical investigation and optimization of castellated beams with sharp and filleted cruciform cellular openings
Mechanics Based Design of Structures and Machines, vol.54, no.1, 2026 (SCI-Expanded, Scopus)
- Publication Type: Article / Article
- Volume: 54 Issue: 1
- Publication Date: 2026
- Doi Number: 10.1080/15397734.2026.2726484
- Journal Name: Mechanics Based Design of Structures and Machines
- Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Compendex, INSPEC, DIALNET, Academic Search Ultimate (EBSCO), Engineering Source (EBSCO)
- Keywords: castellated steel beams, Cruciform steel cellular opening (CSCO), design optimization, failure mode analysis, shear buckling, stability assessment
- Istanbul Gelisim University Affiliated: Yes
Abstract
This study investigates castellated steel beams incorporating cruciform steel cellular openings (CSCO). Two configurations were considered, sharp-cornered and filleted openings, which are introduced as a new unconventional opening configuration for castellated beams. The study aims to evaluate structural trends and cost implications using a differential evolution (DE) optimization framework. The study encompassed 36 design cases, including three lengths (300, 400, and 500 cm), two types of support (fixed-fixed and simple), and two steel grades (S355 and S420), along with 12 comparative design cases for conventional opening configurations. For each case, 50 independent runs were conducted to evaluate solution stability and reliability. This involved determining the optimized cross-sectional dimensions and objective function values, along with statistical dispersion measures. The influence of two fillet radii at the opening corners was investigated through a stress concentration coefficient applied to the Vierendeel action. The results showed that introducing the fillet led to a consistent increase in objective function values, while the maximum utilization rates remained close to the design constraints, with limited sensitivity to the selected radii. Comparison with hexagonal and circular openings indicated that sharp CSCO provides a comparable alternative, whereas fillets increased the objective function values. The DE algorithm produced stable solutions across all configurations with limited run-to-run variation. Failure mode evaluation indicated that shear buckling was the governing failure mode for all investigated configurations. The proposed framework provides an analytical basis for the preliminary assessment of castellated beams with unconventional openings, while future numerical or experimental verification may be conducted. Communicated by Francesco Tornabene.