The article presents the results of the theoretical and experimental research of I-beam behavior under combined bending and torsion. The analysis of numerical models was carried out, including calculations in which the physical and geometrical nonlinearity was taken into account. Based on the calculations, the parameters of experimental models and the value of the applied loads were determined. The samples were tested under the bending and torsion actions up to moment the element lost its bearing capacity completely. The experimental results were compared to the theoretical and numerical calculations. Correspondence between theoretical and experimental results was established (as a rule, the difference does not exceed 15%). The accuracy of the applied numerical methods for the analysis of beams under bending and torsion with due consideration of plastic deformation development was confirmed, which allows using them for developing engineering methods of beam calculating.