Autodesk Revit is a 3D BIM modelling program which is widely used within the construction industry. On top of Autodesk Revit there is a program called Dynamo. Dynamo is an open source visual programming platform for designers. Within Dynamo there are packages like libraries within a programming language. One of the packages is Dyn2Calc.XFEM4U. This package can be used to export and import between Revit, Dynamo and XFEM4U.
Watch this Youtube video to get an impression on how this works.
More information,tutorials and sample files can be found here