Behaviour analysis of phosphogypsum-filled cold-formed steel walls under different lateral loading patterns

Full-scale phosphogypsum-filled cold-formed steel (PFCFS) composite walls were tested under quasi-static loading to investigate their behaviour and damage characteristics under different lateral loading patterns, including monotonic loading, cyclic loading followed by monotonic loading, and cyclic loading. The results showed similar failure modes and predominantly ductile behaviour. However, the loading patterns significantly influenced damage accumulation and seismic performance degradation. Cyclic loading accelerated damage development in sheathing connections and phosphogypsum infill, resulting in notable reductions in stiffness, deformation capacity, energy dissipation and ductility. The Park–Ang damage model was employed to evaluate damage evolution, and five performance levels were defined: intact, minor damage, moderate damage, severe damage and failure. Findings provide a reference framework for the seismic evaluation and design of PFCFS walls.