Kangaroo for shell?

Hello,

In Kangaroo 0.099, I use for stiffness this formula: E*A/L. If you want the geometry structurally consider like a shell, how you consider the cross section for the A? For example: Thickness of Concrete shell is 4cm, can you use for your cross section 0,040m ? For Stiffness: 0,040*E/L ?

Thank you

George