Experiences from previous earthquakes have shown that level of structural damages depends onground features where the structure is placed. Also, it is noted that reinforced concrete framestructures collapse due to the appearance of “weak floor”, especially when are founded on groundswith lower characteristics. In this paper, the seismic analysis of structure is presented on example ofthe six-storey RC frame structure, founded on different ground types. The seismic analysis isperformed in accordance with European regulations and still valid ex-Yugoslavian code PIOVSP'81.At the end of the paper, a comparison of the results was made, and corresponding conclusions werereached.