Warping shear stresses in nonuniform torsion in bridge decks of materials in contact by BEM

In this paper a boundary element method is developed for the nonuniform torsion of arbitrary constant cross section composite bars of materials in contact. The materials have different elasticity and shear moduli and are firmly bonded together. The bar is subjected to an arbitrarily concentrated or distributed twisting moment, while its edges are restrained by the most general linear torsional boundary conditions. Since warping is prevented, beside the Saint-Venant torsional shear stresses, the normal and shear stresses due to warping are also computed. The magnitude of the warping shear stresses due to restrained warping is investigated by numerical examples with great practical interest.