How to model Connectivity between Raft Footing and Wall in Staad?

Question

Good Everybody, 
 I am Modeling a Circular Digester tank of 318Million Litters per Day , I have a doubt how to model the connection between the wall and raft footing. 
 this how I modeled the Raft is 600mm thk and the wall is 350mm thk, I have modeled the walls directly from the raft plate nodes with first layer of the wall to height of 300mm which will be part of raft too how to model this this part of the wall that is inside the raft which type of plate release should i use to simulate the actual behavior. 
 Here with i have attached my staad file for reference too. Staad Editor File.rtf

Sye · Answer

It is a well accepted approximation to model the wall plates to the center of the slab. In doing so, there is a common portion that is accounted for twice as you mentioned, but I would suggest going with that modeling approach rather than trying to create the walls elements from the top of the slab and trying to connect the corresponding nodes using rigid links etc which itself introduces additional stiffness in the model. So I would rather prefer to keep it simple. As long as the wall and the slab plates share common nodes, there will be proper force transfer between the entities.

Sye · Answer

I would suggest that you go with the wall and slab model rather than a wall with fixed support at the base as the former would be a more realistic simulation of the actual structure. You may consider the weight due to the water as well. You do not however need to design the wall for the moments that is within the slab and you may consider only the moment at the face of the slab for the wall design.