Effects of Nonsymmetrical Prestressing Forces on Torsion in Prestressed Thin-Walled Flexural Members

Abstract

Torsional resistance of a single prestressing tendon was derived on the basis of the theorem of virtual work to control the torsional rotation by nonequal prestressing forces on both sides of the webs of a flexural member. The energy formulation revealed that the vertical component of the prestressing force has a significant role in resisting the torsional rotation, whereas the axial component is responsible for the warping-related stiffness. The most influential location of the prestressing tendon was the point where the value of the warping function is maximized. The resulting finite-element equilibrium equations yielded nodal forces at the degrees of freedom corresponding to torsion and warping. Through numerical applications, it was suggested that the conventional solution method of beam finite-element formulation on the basis of the transformed cross section can be improved by adopting the nodal forces derived in this paper. Further, it was shown that the torsional rotation can be controlled by introducing nonsymmetrical prestressing forces on the right and left sides of the webs of a prestressed thin-walled flexural member.