Large displacement analysis of stiffened plates with parallel ribs under lateral pressure using FE modeling with shell elements

•The conventional approach for the design of stiffened plates is discussed,•The load–displacement of stiffened plates is compared based on the large displacement analysis and conventional approach,•The stress distributions in the panel plate resulted from large displacements is discussed,•The benefits of large displacement analysis over the conventional approach are explained,•A potential method for the Limit States Design of stiffened plates based on large displacement analysis is proposed and verified. This study provides the load–displacement behavior of stiffened plates with parallel ribs when modeled using shell elements with and without considering the large-displacement effects in comparison with the conventional equivalent beam analysis (EBA) in which such stiffened plates are simplified into an imaginary beam with the geometrical properties of an equivalent built-up cross-section. This study highlights the advantages of FE modeling with shell elements and large-displacement analysis (LDA) over the existing EBA method and then provides a path for using this method in the ultimate limit state (ULS) design of stiffened plates. The stress distributions in the panel plate part of the stiffened plates are presented to demonstrate the significance of considering the large-displacement effects in the analysis. The numerical investigation indicated that the linear beam theory does not correctly presume the true behavior of the stiffened plates and that the corresponding load–displacement estimation does not align with its behavior predicted by the LDA. The results also demonstrate that when shell element modeling is utilized, the internal forces and stresses in the panel plate are calculated correctly, only if the large-displacement effects are considered in the analysis. Finally, a method for estimating the ultimate load capacity of stiffened plates with parallel ribs is provided, based on the large-displacement FE analysis with shell elements, which can be used to establish empirical design equations.