Abstract
St. Venant torque term of the yield surface equation is often neglected in the plastic analysis of the beams with thin walled open-cross sections. However, after a plastic hinge occures, the hinged section will be free from the state of restrained warping, and so, St. Venant torque terms in the flow rule may play more important role. The yield surface equation of curved I-beam is proposed herein, which is expressed in terms of bending, warping moments and St. Venant torque. Several tests have been carried out with the curved I-beams to prove the availability of the proposed yield equation. The results show that the proposed equation is reasonable and suitable for the simple plastic analysis of the curved I-beams.
