Flexural buckling behavior of axially loaded cold-formed lipped channel columns strengthened with sleeves

This paper presents the experimental results of eight cold-formed lipped channel columns reinforced with sleeves. A numerical model is constructed and validated by the experimental results. Using the validated model, a parametric study based on results of 240 models has been analyzed to examine the effect of different parameters on the columns' behavior. Numerical investigation is adopted using the finite-element program ABAQUS. All specimens are subjected to concentric axial compression force under pinned-end restraint conditions. Geometric and material nonlinearities were considered in the finite element models. Initially, the study presented results and behavior of different cross-sections with slenderness ratios ranging from 100 to 200 using different sleeves patterns. Then the effect of sleeve length is studied. Also, the effect of sleeves on columns with different width to thickness ratios has been studied. Finally, the effect of sleeve-to-channel thickness ratio is examined. It is shown that sleeves have a significant influence on the ultimate strength of the specimens under axial loading conditions. The pattern, the length, and the thickness of the sleeve have a significant effect on the ultimate capacity of the column.