Validation of flattening of box beam under bending moment using finite element method

In this report, in order to discuss the propriety of the derived formula on the flattening of a box beam, especially square beam, composed of thin plates, the non-linear structural analysis with generalized plane strain elements was carried out by the finite element method (FEM). As the results, the derived formula is agreed enough with the results of FEM, and this formula turned out to be useful.