Local buckling of corroded cold-formed steel stub columns

Abstract

Cold-formed steel (CFS) is widely used as the load-carrying members in infrastructure engineering. However, CFS structure, which has been in the corrosive environment for a long time, is often difficult to avoid corrosion. Five corroded CFS stub columns with different corrosion degrees were tested under axial compression and the material properties of the coupon specimens were obtained by monotonic tensile tests. The thickness and initial geometric imperfection were measured using a dial indicator and an ultrasonic thickness gauge, respectively. The failure modes, the relationship between the axial load and lateral displacement, strain and mechanical parameters of the corroded CFS stub columns were discussed. A numerical study was undertaken using validated finite element models. Finally, the design rules for the corroded CFS columns were analyzed. The results indicated that the yield strength and ultimate strength reduction factor for corrosion decreased linearly with respect to the thickness loss ratio and the elastic modulus reduction factor for corrosion decreased nonlinearly with the thickness loss ratio. The axial displacement corresponding to the axial strength and the axial strength decreased with the increase of the thickness loss ratio. The axial strength predicted by the North American Specification (NAS) were more accurate than that predicted by the Chinese Technical Specification (CTS).