For mixed structures consisting of members and surfaces, you can use the *.dxf, *.ifc, *.dgn, *.sdnf, and *.dat formats for the import in RFEM. A particular problem here is that the CAD and structural analysis software "speak different languages". While CAD software describes geometry precisely, structural analysis software concerns the design of components in a simplified model. For example, if a wall is abutting another wall perpendicularly, it ends at the outer edge of the next wall in a CAD program, while a structural analysis program requires an intersection of the system axes.
As a solution to this problem, direct interfaces have been developed in cooperation with Tekla Structures and Autodesk Revit Structure. The programs include an analytical model to solve such connection problems automatically. Moreover, the analysis model can be adjusted before exporting a structure.