Local failure behavior of cellular beams: A parametric finite element study of web-post bending moment

Cellular beams are widely used in modern structures owing to their unique geometry and the benefits of web openings, which allow convenient integration of building services. However, limited research has focused on their local failure mechanisms, particularly the web-post horizontal moment failure (WPHMF) caused by bending. To ensure reliable design, this study investigates WPHMF through a comprehensive parametric analysis using finite element (FE) modeling. The considered parameters include the opening ratio, slenderness ratio, and beam section size. The FE model, developed in ABAQUS, assumes steel to be homogeneous, isotropic, and perfectly plastic. Results show that the web-post horizontal moment (WPHM) predicted by ANSI/AISC 360-16 is generally overestimated compared with FE results, especially for beams with larger sections and smaller opening ratios. On average, ANSI/AISC 360-16 overestimates WPHM and failure distance by approximately 88.36% and 151.16%, respectively. To improve prediction accuracy, this study proposes new regression-based equations to estimate both the magnitude and location of WPHMF using statistical analysis. The findings enhance understanding of cellular beam behavior, emphasize the significant influence of geometric parameters, and support the development of more accurate design provisions to mitigate WPHMF. These equations provide substantially better agreement with the FE results, with coefficients of determination ( R ²) of 0.9998 and 0.9946 for the WPHM and failure location, respectively. This indicates that, in addition to ensuring safety, the proposed equations can also help improve design efficiency.