Effect of initial imperfections in numerical simulations of collapse behaviour of stiffened plates under compression

The slenderness of plated structures together with a generalised use of high strength steel leads to a great importance of stability phenomena. The practical way to deal with such problems is to use rules proposed in design codes. A common alternative to design codes is the use of non linear finite element simulations. One of the most sensitive point in these simulations is the choice of the initial imperfections to be introduced in the model. The present paper discusses the effect of initial imperfections on the calculated collapse load.
Several parameters are considered (shape, magnitude and direction). Results of numerical simulations are also compared with those of a design using Eurocode 3 or ECCS Recommendations. Two cases of plate geometry are studied (plate with one single stiffener and plate with multiple stiffeners).