A new feature in PLAXIS 2D 2011.00 is the input of anisotropic properties for plate materials by means of an out-of-plane axial stiffness (EA2) parameter. However, this anisotropic behaviour is not taken into account by the calculation kernel during the calculation of axisymmetric models, and so the plate behaves as an isotropic material.
For geogrid materials, the anisotropic behaviour is working correctly
Note that this structural anisotropic behaviour is only taken into account in axisymmetric models.
This issue is fixed since PLAXIS 2D 2011.01