The paper presents the results of research on fragments of thin-walled coverings made of aluminum alloy. The exmined structures were subjected to shear stresses leading to post-critical deformations. Three types of elements were analyzed: an element without stiffeners (the referencial one), an element with three stiffening ribs and an element with five stiffening ribs. The results of numerical analyzes and static experimental research were presented. Althought this kind of solutions is commonly used in various aircraft structures, the publications about it are usually hard to rich. The research concerning ribbed stiffeners are usually performed inside laboratories of aerospace concerns and their results are not published in the open sources. The general direction of analyses of this solution is indicated in presented study.