Experimental investigation on the seismic performance of phosphogypsum-filled cold-formed thin-walled steel composite walls

Cold-formed steel (CFS) is generally used in the construction industry for low-rise and multi-story buildings. In such structures, CFS walls are the main load-carrying elements. The traditional CFS wall has a low load-carrying capacity and poor seismic performance, which is the main reason for structural damage under natural disasters and also restricts the application of CFS structures in medium-and high-rise buildings. In this study, to improve the shear capacity and seismic performance of CFS walls, an innovative CFS wall filled with phosphogypsum (PG), called phosphogypsum-filled cold-formed thin-walled steel (PFCFS) composite wall, is presented. Taking the axial compression ratio, PG strength, and steel tube's wall thickness as the study parameters, seven full-scale specimens have been fabricated and tested under cyclic lateral loads. The failure processes, failure modes, load-displacement response, strength and stiffness degradations, and energy absorption capacities of all the specimens are comprehensively investigated. The test results indicate that the specimen with a low axial compression ratio exhibits a connection failure between the CFS frame and hold-downs. For other specimens, the damage to the component materials leads to the final specimen failure. The axial compression ratio and the wall thickness of steel tubes have a significant influence on the seismic performance of the composite walls, while the PG strength has a much lower impact on the seismic performance. In addition, an analytical model and calculation formulas are proposed for predicting the shear capacities of the PFCFS walls. The effectiveness and accuracy of the proposed formulas are verified by comparing the calculated and test values.