Structural behavior of cold-formed steel trusses incorporating built-up section chords

Cold-formed steel (CFS) built-up box sections often exhibit axial strengths greater than the sum of their individual components. Since truss members primarily carry axial forces, they are well-suited for replacement with such sections. Incorporating high-performance Howick Rivet Connectors (HRCs) enables these built-up members to substantially improve the load-bearing performance of truss systems. However, related studies remain limited. This study addresses this gap by investigating the structural performance and design methodology of such trusses for potential applications in modular construction. A comparative experimental program, involving 64 specimens, was conducted to evaluate the axial capacity and failure behavior of built-up columns with HRCs versus conventional screw fasteners. Finite element models were developed and validated against experimental results, enabling a parametric study of trusses with built-up chord and diagonal members. Among the truss configurations investigated, replacing only the chord members with built-up sections achieved the highest ratio of serviceability limit strength to self-weight and demonstrated the most structurally efficient performance. A practical design method was subsequently proposed to enhance the accuracy of truss strength predictions by accounting for the effects of eccentric compressive loading in the chord members.