W. JAGER and H. BERGANDER Consultants, Dresden

In the standards to prove buckling safety, approximate equations are prescribed which differ in certain fields. The results cannot be assessed by comparing the different approximations. For this purpose, a theoretical approach must be used. In this paper, the solution is found on the basis of a physically nonlinear beam theory. The material is unable to transmit tensile stresses. Under compressive stress linear behaviour is assumed. This selection is explained. Especially, the assumptions on the deformation and on the loading behaviour are separated. This separation is required to remove contradictions from experimental results.