Experimental study on the axial bearing capacity of built-up cold-formed thin-walled steel multi-limb-section columns

To solve the shortcomings of single-limb or double-limb cold-formed thin-walled steel column easy to buckling failure and low bearing capacity, a new cross-shaped built-up cold-formed thin-walled steel multi-limb-section is proposed for columns. The structure is composed of several single-limb cold-formed thin-walled steel C-channel sections. The flanges and webs are connected by self-drilling screws. In order to assess the mechanical properties of this built-up multi-limb-section column and the influence of the slenderness ratio on the column behavior, the axial loading tests were carried out. Three kinds of single-limb column and built-up multi-limb-section column with different ratio of slenderness were tested. The deformation process, failure mode and bearing capacity were analyzed. The SC specimens failed with local buckling and distorted buckling, while the MC and LC specimens failed with local buckling and global instability. For the built-up multi-limb-section column, the section combination multiple is 12. Compared to the section combination multiple, the bearing capacity combination multiple is much higher. The SQ specimens' combination factor is about 1.1, the combination factor of MQ specimens and LQ specimens are about 1.4 and 3.0, respectively. It is concluded that the overall combined-performance and structural efficiency of the specimens is proportional to the combination factor.