Torsional stiffness of reinforced concrete rectangular members

The paper deals with the determination of the torsional stiffness of rectangular reinforced concrete members under pure torsion and torsion combined with bending and shear. The energy principle is applied to a four-plate shear wall model representing the member to obtain the stiffness under pure torsion. The range of validity and the modification needed for the expression for stiffness thus obtained when the member is subjected to bending moment and shear force are investigated with reference to the results of tests on reinforced concrete space frames.