I have designed a lot of multi-story buildings and always felt that the reduced floor to floor height often decreased the cost architectural items, such as exterior facade. It also can allow easier access for mechanical. So, I think the advantages goes beyond just steel tonnage. If you have a...
If you have values provided by a Geotechnical report you don't need to use the UBC minimums. You should only increase the values from the Geotechnical report based on his recommendations not based on the UBC table. I typically only use the UBC tables if I am working a small project that does...