Abstract： To investigate the buckling modes and failure characteristics of cold-formed thin-walled
steel quadruple-limb built-up box-section columns, column specimens were tested under axial and
eccentric compression, respectively. The load-displacement curves and ultimate bearing capacity of
specimens were obtained. The finite element models considering material, geometry and contact
nonlinearity were also built to simulate and analyze the specimens. The results of FEM agree well
with the test results, validating the reasonability of finite element method. With the finite
element models, the influences of slenderness ratio, spacing and location of screws, eccentricity
and eccentric direction on the eccentric mechanical behavior of these columns were studied. The
results show that the hinge joint can be simulated by double knife-edge support very well. Those
limbs of built-up columns can work in collaboration with each other when the spacing of screws is
300mm. The failure mode of specimen in axial compression or in eccentric compression around weak
axis is the overall flexural buckling. The failure mode of specimen in eccentric compression
around strong axis is the flexural-torsional buckling, but the torsion effect is not obvious. The
ultimate bearing capacity and stiffness of built-up columns in eccentric compression may decrease
with the increase of slenderness ratio or eccentricity. With the same eccentricity, the ultimate
bearing capacity and stiffness of built-up columns around strong axis are slightly higher than
those of columns around weak axis.
