New materials such as fiber reinforced plastics, pure polymers etc. are used to an increasing extent in load carrying structures, including shells. Typical examples are shell support structures (skirts) in process towers, tanks and pressure vessels, ships, stacks and scrubbers. Fiber reinforced plastics provide a good potential for weight optimization through variation of the layup angles and stacking sequence of the fibre material as is done in reinforced concrete structures. Furthermore, by stiffening the shell or designing it as a double layer shell, i.e. a sandwich structure, the buckling resistance can be increased considerably.