Abstract: According to the experimental results of limit torque in eight RC structural members under the combined action of axial tension and bending twisting moment, the author studies the damage forms of the members, the stress-strain variation law of the longitudinal and the crossed steels. Based on the theory of changeable angles in the truss, the author derives some relevant equations forthe RCstructural members un- der the combined action of axial tension and bend twistingmoment. The auther also proposes a practical for- mula for calculatingthe ultimate torque ofthe memberswhich is underthe combined action of a comparative- ly large axial tension and bending twisting moment.