In-Plane Seismic Performance of Double-Sided Steel-Sheathed Cold-Formed Steel Shear Walls: Experimental Evaluation and Design Implications
A total of 16 full-scale double-sided steel-sheathed cold-formed steel (CFS) shear wall specimens were tested to evaluate their in-plane shear performance under monotonic and cyclic loading, focusing on the effects of sheathing thickness and screw spacing. Under cyclic loading, increasing sheathing thickness and reducing screw spacing resulted in increases in shear capacity of up to approximately 120% and increases in initial stiffness of up to 20%, accompanied by a reduction in ductility due to restrained inelastic deformation. The walls exhibited a stable hysteretic response governed primarily by ductile, connection-related limit states. Observed failure modes included sheathing buckling, screw tilting with bearing deformation, pull-through, and screw shear failure. Full-field three-dimensional digital image correlation (3D DIC) measurements confirmed the development of diagonal tension-field action and distributed load transfer in double-sided walls, mitigating frame demands commonly reported for conventional single-sided systems in prior studies. Although double-sided steel sheathing requires additional material and fastening, the resulting gains in stiffness and strength can reduce the required wall length or number of shear walls in seismic design, improving overall system efficiency. Based on a combined database of 32 shear wall tests, including results from the present study and relevant literature, a modified effective strip method (ESM) is proposed to estimate the shear capacity of double-sided steel-sheathed CFS shear walls. The proposed formulation shows good agreement with experimental results and satisfies the target reliability requirements adopted for load and resistance factor design (LRFD), limit states design (LSD), and allowable strength design (ASD) design methods. These findings support the application of double-sided steel-sheathed CFS shear walls within a capacity-based seismic design framework.