The shape of the deformation of cross-section is given by the conditions of support of the sheet fastening. Corrugated sheets are used to be fastened in the troughs of corrugations. It is assumed that the sheets are fastened in every trough. Equation is given for the shear modulus of elasticity. The value of the shear modulus depends on the corrugation cross-section shape, on the sheet thickness and on the length of the sheet panels.