On the modelling of compressed long plates related to sheet-section behaviour

For the behaviour of thin-walled sheet-sections without stiffeners, often a square part of the flange is modelled. However, once the sheet-section includes stiffeners, the flange can only be studied by modelIing a long plate, preferentially with a prescribed displacement function along the length. For this long plate, even without stiffeners, convergence problems occur if a quasi-static solution method is used. This has been solved by a dynamic (explicit) solution procedure with which a parameter study was carried out. For small imperfections, so-called mode-jumping occurs always whereas for large imperfections this occurs less often. During mode-jumping, the wave-length and location of the buckles change. As modejumping occurs before plasticity starts, this leads to the question whether existing failure predicting models should be used in their current form. Finally, it is shown that the same conclusions are valid for plates with stiffeners.