Numerical investigation and design of lightweight aggregate concrete-filled cold-formed built-up box section (CFBBS) stub columns under axial compression.

Cold-formed built-up box sections (CFBBS) have emerged as a promising solution for applications in light gauge steel framing systems and modular construction. However, they suffer from the inherent local buckling effect. Concrete infill has proven effective in mitigating this issue, yet existing codified provisions lack specific guidelines for the design of concrete-filled CFBBS stub columns. This paper proposed a design methodology that aims to predict the ultimate compressive strength of lightweight concrete-filled CFBBS stub columns. Leveraging finite element (FE) modelling techniques, this study augmented the existing test database and shed light on parametric influences, considering practical considerations, on the structural performances and axial compressive behaviour. The proposed design approach demonstrated superior prediction accuracy and consistency compared to other evaluated design approaches in this study. • Finite element modelling of lightweight aggregate concrete-filled CFBBS stub columns. • Parametric study, incorporating practical considerations, on various aspects of structural performance. • Discussion on mechanical behaviours, encompassing load–end-shortening relationship and interfacial stress analysis. • Proposal of a reliable and accurate design methodology for predicting ultimate compressive resistance. [ABSTRACT FROM AUTHOR]