Axial compression experimental on T-section special-shape light-weight foam concrete-filled cold-formed steel built-up columns

This paper proposes T-section special shape light-weight foam concrete-filled (FCF) cold-formed steel (CFS) built-up columns, which can be used as the side columns that easily connect CFS shear walls from three directions. Light-weight foam concrete was used to mitigate the buckling failure and to increase loading capacity of the columns. Axial compression tests were conducted on four hollow columns and six FCF-CFS columns, and the failure modes as well as the buckling mechanisms of these specimens are analyzed. Finally, the codes from different countries are used to predict the ultimate capacity of these specimens. The results show that (1) the ultimate capacity of the specimens increased to 37.0 similar to 294.5 % if 10 MPa FCF was used, and the improvement was 70.8 similar to 170.7 % if 6 MPa FCF was used; (2) the FCF mitigated local buckling of the specimens and improved their ductility, however, the final failure modes did not obviously change; (3) although the GB50018-2002 and the AISI-S100 can effectively calculate the ultimate capacity of the hollow specimens, almost all codes cannot accurately predict the ultimate capacity of FCF-CFS specimens due to the complex behavior between the built-up special-shape section and FCF. The results provide insights for performance enhancement of columns in CFS structures.