Estimation of lateral stiffness for gypsum-filled cold-formed steel shear walls

This paper reports an experimental and theoretical investigation of gypsum-filled cold-formed steel (CFS) shear walls, for the purpose of addressing the estimation of lateral stiffness. A series of gypsum-filled CFS shear walls were tested under reversed cyclic loading. The infill walls declare the limit states in the failure of screw connections as well as the compressive failure of gypsum fillings. Besides, the shear performance of screw connections between CFS profiles and sheathings were also investigated by the local tests. The contributions of lateral stiffness under shear force mainly include the sheathings as stressed skins and the infill gypsum as bracing bars. A theoretical prediction of lateral stiffness for CFS infill walls was proposed based on superposition methods, which has a good agreement with the wall tests. Moreover, the shear stiffness of screw connections is required to determine the contribution of sheathings to lateral stiffness. Considering the extrusion deformation of sheathings along with the bending deformation of CFS profiles caused by the tilt of screws, a theoretical method was recommended to estimate the shear stiffness of screw connections.