Experimental investigation of C-beams with non-standard flanges

•Beams with box flanges lost stability before stresses exceeded the yield strength.•Beams collapsed in elastic–plastic and plastic range.•The inner part of compressed flanges moved inward just from the beginning of tests.•The agreement between the experimental and analytical results was satisfactory.

The paper presents results of experimental investigations of stability and limit load of cold-formed thin-walled channel beams with non-standard flanges subjected to pure bending. Critical and limit loads were determined using a strength testing machine. Obtained results were compared with analytical solutions. The influence of non-standard flanges on the critical load and limit load was shown as well.