Local effects due to warping in straight homogeneous or composite beams

With regard to straight homogeneous or composite beams subject to a shear f orce and a bending moment, we propose an analytical method of calculation f or local stresses near critical sections, such as built-in ones. By means o f Hellinger-Reissner variational principle, we get a new expression for the warping eta(x), in order to compute stresses near those critical sections. (C) Academie des sciences/Elsevier Paris.