Towards establishing the reuse design rules for cold-formed steel channel stub columns

This study systematically investigates the reusability of cold-formed steel (CFS) stub columns experiencing local buckling. A series of eight cyclic loading tests, including an initial assessment and a final test after accelerated corrosion simulating ten years of service, were performed on CFS channel columns with varying slenderness, thicknesses, and embossments but consistent length and fixed ends. The experimental program encompassed 231 individual tests on 24 specimens, comprising 192 reuse cycles and 39 post-corrosion evaluations. Detailed analyses of structural stiffness and strength at each cycle enabled determination of the reuse resistance factor (ϕR) and prediction of reusable strength (Pn−R) over successive applications. The results establish reuse thresholds for load levels and permissible numbers of cycles. Key design recommendations include limiting reuse for sections thinner than 0.5 mm with normalized slenderness above 6.27, enabling up to two additional reuses for sections 1 mm or thicker with slenderness between 2.16 and 3.21, and providing a new empirical model for ϕR. Reusable strength is shown to be reliably estimated from original material properties. These findings contribute robust experimental evidence and guidance for sustainable reuse of CFS columns in structural engineering practice.