Novel design method of screwed connections of cold-formed steel built-up plates

Abstract

The ultimate capacity and failure modes of composite plates have been widely investigated, especially those assembled by using self-drilling screws. The cold-formed steel (CFS) built-up plate connected by self-drilling screws is the research object in this paper. The screw built-up plate (SBP) is taken from the built-up flanges of the CFS built-up double-limbs closed column. In conjunction with the author's previous experiment, a theoretical model for the critical buckling stress of the SBP is presented. The innovation lies in considering the influence of the shear slip effect in the theoretical model. The kinematic relations between single plates of the SBP are given according to the energy method, and the stress calculation equation of the SBP is proposed through theoretical derivation. In this equation, a thickness reduction coefficient of the SBP is proposed. Subsequently, the influence of key parameters on the proposed equation is studied by finite element analysis. It indicates that the proposed equation of the critical buckling stress in this paper can truly reflect the true loading of SBP through comparative analysis of multiple parameters. Additionally, the study in this paper lays the foundation for the calculation of the bearing capacity of the CFS double-limbs closed built-up columns.