Abstract
For the box beams which compose the frame structure of a vehicle, and consist of thin plates, some approximate expressions which simply obtains the shear buckling stress under torsional moment is derived. These approximate expressions are proposed by the knowledge from the analysis based on the energy method. The accuracy of these expressions is investigated as compared with the results acquired in the buckling eigenvalue analysis by FEM. As the results, the difference of shear buckling stresses between the best expression and FEM is less than about 5% as for the aspect ratio of the cross section between 0.4 -1.0.
