In PLAXIS 3D 2016 the CAD import functionality has been improved, supporting *.DXF, *.STEP and *.brep formats. NURBS surfaces, solids, splines can now be imported easily. Native Autocad solids can be imported without the need of discretizing them into triangulated objects first. This does not only save you time in Autocad, it has benefits for PLAXIS as well. Because of the absence of triangulation, the PLAXIS 3D mesher can more easily create better meshes with less elements for both simple and complex projects, by using the mathematical representations of the imported objects.
How do I import a geometry in PLAXIS 3D?
[Tips and Tricks]
PLAXIS 3D 2016: Fully parametric geometry
Can I reuse existing PLAXIS 3D geometrical objects in a new project?