I have used RAPT too and i found it extremely useful for prestressed concrete design. i would like to add here that it can also be used for reinforced concrete slabs and beams without prestressing and has modules to design columns, walls etc.
There is also another software ADAPT for prestressed...
Dear nades, I think what 1161 says about the soil spring to be KFY is correct, as staad considers y direction as the normal gravity direction,the direction in which all soils support the structures resting on them.
