Restoring force model of phosphogypsum-filled cold-formed thin-walled square steel tube composite wall

Abstract

The phosphogypsum (PG)-filled cold-formed thin-walled square steel tube (PFCFS) composite wall is a new type of cold-formed steel (CFS) wall. The restoring force model (including the skeleton curve and hysteresis rules) is an important performance of this type of walls. Based on the characteristics of load–displacement curves of the walls, a Pinching4 model for the skeleton curve of the walls is developed. The lateral stiffness and shear capacity of the walls are calculated by theoretical formulas, while other parameters are determined through data fitting. Moreover, the hysteresis rules of the walls adopt the Pivot model, and the Pivot parameters (α and β) of the walls are determined based on the principle of equal energy. Finally, based on the above restoring force model, the energy dissipation analysis for the walls with different parameters was conducted. The results show that improving the PG strength, stud thickness, or reducing the height-width ratio of the walls significantly enhances the energy dissipation capacity of the wall; increasing the OSB thickness, axial force ratio, or reducing the screw spacing gradually improves the energy dissipation capacity of the wall; the OSB configuration and the stud strength have a smaller impact on the energy dissipation of the wall; the energy dissipation capacity of the wall when the hold-down fails is lower.