Abstract: Based on the experimental and numerical simulation results of U-shaped thin-walled concrete girders under combined actions of bending, shear and torsion, an equivalent method of warping moment Mω and warping torque Tω is proposed, and then a design method of U-shaped thin-walled concrete girders under effect of combined bending-shear-torsion considering torsional warping is proposed. The differences on internal forces and calculated ultimate loads are analyzed between cases of considering and non-considering torsional warping respectively. The results show that there are significant differences both on the types and values of internal forces; when the torque-bending moment ratio is small (about<1∶8), the non-warping calculated ultimate load is relatively larger, and when the torque-bending moment ratio is large (about>1∶8), the nonwarping calculated ultimate load is relatively smaller.