I have been trying to design columns in staad RCDC, My building model have some columns starting at level 0.0 and some other columns starting at level 3.0. Now when I choose to consider this level 3m, columns those who starting at 0m gives much higher steel then staad pro output. But when I merge that level 3m with the above floor level it gives steel near to what staad pro output gives. PS::0m and 3m are the levels at which footings of those respective columns started/lies.