I was able to find similar topic, but conclusion was not clear to me, and as I got sumilar problem, I decided to write myself. The model I am talking about was already discused in:
http://forums.autodesk.com/t5/Autodesk-Robot-Structural/panels-displacaments/td-p/3612428
Problem is that after reinforcement calculation, in foundation slab I found minimum reinforcement of that slab up to 51,35cm2/m. I tried to check it myself According EC2 section 7.3.2, and in worst case scenario I go at least 3 times less reinforcement than in calculation file.
I couldn't find out how robot calculates this mimimum reinforcement.
Maybe you could give some clues.