Hello, there is a granary project with a size of 40 m x 20 m, completely surrounded by curtains on 3 sides (screen height 8 m); 1-) When I make a raft foundation, the height of the raft foundation is too high because there is no column, how convenient is it to change its value with a clear span to reduce this? 2-) Let me define the sub-basement as I have shown in the picture. Does it create a problem by making a 40-60 cm high sub-basement curtain in appropriate sizes and solving it with a continuous foundation?