There are several workflows available for a workflow with Tekla Structures.
Tekla to XFEM4U
Can be done using the XML Interface, SDNF or DWG/DXF(2D only). The XML Interface is this most advanced way to communicate from Tekla to XFEM4U. But is requires some additional settings and programs Tekla.
XFEM4U to Tekla
Can be done using the SDNF file format.