Problems to mapp stresses in membrane element (sigini)

[aaltuna]

Dear,

I am trying to introduce initial reidual stress in the surface of my piece. I am doing that with sigini subroutine.
I introduce in shell elements the residual stresses by KSPT (Section point number within the current layer.)
I have never use membrane elements and I do not know if it is logical to employ this type of element to introduce residual stresses and how can introduce in this elements.
This elements has KSPT (Shell has 5).

Any help please.

REgards,

Ane