In the article a calculation of the bending moment and bimoment for different occasions single- and multi-span continuous thin-walled channel section beams using B.P.E. Clapeyron and N.L. Kuzmin methods have been made. Article considers the cases of uniformly distributed loading with the eccentricity relative to the center line of the bend sections of one-, two-, three- and five-span beams with with spans 2.5 meters long and 5 meters. Ratio between the bending moment and bimoment in feature points and proportionality coefficients between the bending moment and bimoment has been calculated experimentally. Article suggests a formula that allows to determine bimoment, if only the bending moment and the eccentricity of applied load are given.