What is the maximum distance for a floor to hold between two successive columns? NOT using trusses.

It really depends on how the entire structure is designed. We usually specify the distance between columns and the engineer will design accordingly. Of course, the final design will be constrained by the site, budget and other factors. Even without trusses, you'll still need horizontal structural members to tie the columns together. These could be R.C. beams, steel universal sections, flat slabs, etc. So there's no definite answer to your question.

Thanks, just interested to know.:)