ArchiCAD (11) can only read 3D DXF/DWG afaik, so you have a
problem there. We have Rhinoceros here to handle the file format
problem. But the files are very heavy in ArchiCAD, so the best way
is to use GDL (write code for the geometry), then it's very
fast.
If not, could you tell us what file of types that archicad can read / open ?