Experimental investigation and finite element analysis of web-stiffened cold-formed lipped channel columns with batten sheets

This paper presents an experimental investigation and a finite element analysis on web-stiffened cold-formed lipped channel columns with batten sheets connected between the column's two lips at reasonable space. Initially, the paper presents the static compressive test results on 18 specimens under pinned-end restraint conditions with different column length and load eccentricities considered. It is shown that the batten sheets exert significant influence on both the buckling modes and the ultimate strength of the specimens under positive eccentric loading and/or axial loading conditions, while they just have few impacts on that of the specimens under negative eccentric compression. Strengthened by the batten sheets, the columns performed obviously higher ultimate strength under axial and positive eccentric compression compared with the ones without batten sheets and the strengthening effect increase with the increase of column length. Furthermore, the tested specimens were also numerically investigated by finite element program of ANSYS. Geometric and material nonlinearities were both included in the finite element models and it is demonstrated that the numerical analysis can closely predict the ultimate strength and the buckling behavior of the tested columns. Finally, a parametric study was conducted by using program of ANSYS, in which effect of the increasing lip stiffener width and varying batten sheet space were all investigated and it is concluded that the contribution of the batten sheets to the columns' strength decreased notably with the increasing lip width or batten sheets' space for axial and/or positive compressed columns. The best choice of the distance between batten sheets (d≤λ/3) for axial compressed lipped channel columns must also be a reasonable choice for positive compressed columns.