Structural analysis using STRAP - Soil coefficient parameter

[oneintheeye]

Hi, I am applying a large raft foundation to soils subject to settlement. The programme will allow me to enter a spring constant as normal or a further option in the latest version of the programme a soil coefficient to which the program assigns spring constants based on distance between nodes etc. (At least that is what I believe its doing). Is this soil coefficient the k value? (modulus of subgrade reaction). I realise some of this is covered in other threads but can't find one that will directly give me any assistance on this particular query. Any help appreciated, thanks.