The influence of the in-plane warping on the behavior of thin-walled beams

The paper presents a theoretical study of the importance of the in-plane de formation on the structural behavior of thin-walled isotropic and composite beams which are subjected to bending and torsional moments. To separate th e effects of the out-of-plane warping and the inplane warping, the overall solution methodology is based on a generic combination of two complementary "inner" and "outer" solutions. The inner model is based on numerical optim ization tools which are employed to determine the in-plane deformation that will ensure a stationary (minimum) state of the total potential energy. Th e outer model performs global solution for cross-sections that are rigid in their own plane but includes the out-of-plane warping. The overall solutio n is capable of determining the influence of the in-plane warping on any ex isting approximate numerical scheme that do not include this deformation co mponent. The results correlate well with known analytic solutions for isotr opic tubes under pure bending. A parametric study of the relative importanc e of the in-plane warping as a function of the geometry and the loading par ameters in rectangular thin-walled isotropic and composite beams is also pr esented along with some buckling considerations. (C) 2000 Elsevier Science Ltd. All rights reserved.