Symmetry
Use the Symmetry node to add a boundary condition that represents symmetry in the geometry and in the loads. A symmetry condition is free in the plane and fixed in the out-of-plane direction.
Shell Properties
The selection in this section only acts as a filter for the boundary selection. The constraint is applied all through the thickness of the shell.
Location in User Interface
Context Menus
Ribbon
Physics tab with Layered Shell selected: