Consistent equivalent geometric imperfections for the numerical buckling strength verification of cylindrical shells under uniform external pressure

The progress of non-linear FE-methods allows it nowadays to simulate the load-bearing behaviour of steel shells taking geometric and material nonlinearities and imperfections into account. In this paper it is investigated for the basic buckling case of uniform external pressure, which equivalent geometric imperfections have to be applied in the numerical analysis (GMNIA) to achieve the experimentally determined buckling resistances. Single longitudinal imperfections are better suited than eigenform-affine initial deformations. Proposals for the imperfection amplitude and imperfection width are submitted. The results are compared with the regulations of the Eurocode. Essential modifications are discussed.