Ultimate bearing capacity of U-shaped thin-walled RC beams under pure torsion and bending-torsion interaction

U-shaped thin-walled RC beams are widely applied in urban railway transit in China. But research reference related to the calculation of ultimate bearing capacity of U-shaped beams under torsion and coupled effect of bending and torsion is extremely rare. A calculation model for evaluating the bearing capacity of U-shaped thin-walled RC beams was proposed on the basis of experimental results of six beams tested under pure torsion and bending-torsion. The principle of stiffness distribution and Vlasov's theory for open thin-walled members were applied in the method. Six U-shaped RC beams were calculated by the method. And comparisons between calculated and test values of six tested beams validate the calculation model.