Yes, many thanks.
I did what you suggested but had no success.
It drives me to think that the problem was that my file is V8
while my microstation (Intergraph) version only reads V7.
What I did?
I opened the V8 file with microstation (Bentley), and exported it as V7,
and voilà¡¡¡. Now, microstation (Intergraph) imports all my files ¡¡¡.
However ...
The imported structural-elements are not inteligent, they are just solids
so I cannot use my structure in PDS to detect interferences and manage bill of materials, etc.
Any thoughts on this?
Many thanks for all your help, indeed.