If rockets are reusable, why not buildings? Reuse evaluation for cold-formed steel unequal-leg lipped angle columns

Within the drive for achieving Circularity in Construction, this paper examines the reusability of cold-formed steel (CFS) unequal-leg lipped angle columns through experimental and design assessments. In the absence of explicit design guidelines for the reuse of CFS structural members, this investigation focuses on four main tasks: (i) evaluation of the design strength of CFS unequal-leg lipped angle columns; (ii) development of a proposed reuse design approach for CFS structural members to determine the remaining strength based on repeated reuse test cycles; (iii) assessment of the influence of long-term corrosion on the reuse potential of CFS columns and; (iv) comparison of material properties of used and unused structural members to determine the material characteristics for reuse design. To achieve these tasks, a total of 154 tests, including repeated tests for reuse, on 48 CFS unequal-leg lipped angle columns are carried out in the present study. Irrespective of reuse, it is found that modifications to the classical fixed-end boundary conditions need to be incorporated in the local-global interaction design of CFS columns. Overall, the experimental results show that, apart from the first use, CFS columns can be further reused up to two times, in conjunction with a proposed “safe reuse resistance factor” and in combination with the original characteristic material properties.