Within the code-family of the Eurocodes, provisions for aluminium shells are given in EN 1999-1-5 (EC9) [1]. EC9-1-5 is listed in the Bavarian List of Technical Building Regulations. Thus, in Bavaria as well as in other Federal States of Germany it is mandatory to use EC9-1-5 for the verification of silos. A typical aluminium silo for industrial products might have a diameter of 3 m, a bin height of 10 m and wall thicknesses of 4 mm / 5 mm. The aluminium alloy EN AW-5754 [Al Mg3] O/H111 (EN 485-2 [2]) would be typical as well. Relevant for determining the required wall thickness is the buckling resistance under axial compression in the skirt and axial compression with coexisting internal pressure in the silo bin. When some obvious shortcomings in the formulae for coexisting internal pressure were investigated, it was found that there is a big discrepancy between scientific research, which has been done on the imperfection sensitivity of aluminium shells and the design equations in EC9-1-5. In the present paper an effort was made, in order to tackle these discrepancies and make clear, in which points the code needs amendment.
