Research on the Shear-Slip Constitutive Relationship of Self-Tapping Screw Connections for Cold-Formed Steel Plates

As an important connector in cold-formed steel structures， the shear performance and failure modes of self-tapping screws directly affect the mechanical properties and failure modes of the structure. At present， researchers worldwide have focused mainly on the shear capacity of single self-tapping screws， while the studies related to the shear-slip constitutive relationship are scarce. Therefore， this paper summarized and analyzed both previous shear test results of single self-tapping screws and the tests conducted in this study. Using the XTDIC three-dimensional full-field strain measurement and analysis system， an in-depth analysis of the shear failure mechanism of self-tapping screw connections in cold-formed steel was conducted. Considering the effects of screw diameter， plate thickness， and material properties， two shear-slip constitutive models corresponding to the two major shear failure modes of such connections were proposed， which showed good agreement with the experimental results.