Experimental Research on Mechanical Properties of Phosphogypsum-Filled Cold-Formed Thin-Walled Square Steel Tube Walls Under Axical Compression

In order to improve the mechanical properties of cold-formed thin-walled steel (CFS) walls under axial compression, a new structural measure of infilling phosphogypsum in CFS walls was proposed. 4 full-scale test specimens were designed and fabricated with consideration of the phosphogypsum filled area and the measures with or without sheathings. Through axial loading tests, the failure process of the specimens was described, and the failure mode, axial force versus displacement curve, strain curve and bearing capacity of all specimens were analyzed. The test results indicated that the main failures of the specimens were the local crushing of the square steel tube wall studs, the tearing of the wall sheathings, the crushing of the infilled phosphogypsum, the distortion of the tracks, etc. Compared with the hollow section specimen, the bearing capacity of the specimen with phosphogypsum only filled in the steel tubes was increased by 37.4%. For the specimen with phosphogypsum filled in steel tubes and phosphogypsum filled in the area between studs, the bearing capacity was increased by 115.7%, indicating that the infilled phosphogypsum could effectively improve the axial load bearing capacity of the CFS wall. The comparison of specimens with and without sheathings showed that the wall sheathing had a slight influence on the axial load bearing capacity. In addition, formulas for calculating the axial load bearing capacity of the walls was also proposed in the paper. The verification results showed that the formulas had good calculation accuracy.