TORSION OF CLOSED CROSS-SECTION THIN-WALLED-BEAMS - THE INFLUENCE OF SHEARING STRAIN

In this study a theory of rectangular closed cross-section thin-walled beams subject to torsion is presented, with express consideration being given to the shearing strain. The equations of equilibrium (in weak form) of the elastic system subjected to twisting distributed loads and to bimomental loads, in the unknown theta (angle of rotation by torsion) and beta //w (average shearing strain in the webs) - or phi //w (distorsional angle) - are derived from the variational method of Minimum Potential Energy. It is shown that the present theory, including the known results, determines, depending on the actual constraint conditions, the shearing stress which can differ considerably from the results predicted by the Non Uniform Torsion.