This dialog can be accessed from the Model > Model tools > Create new raft model menu command. This command creates a new model from the existing model by taking the geometry and updating it with nodal support stiffnesses based on the soil stiffnesses calculated for the specified raft analysis case.
Raft analysis is a soil-structure interaction analysis, iterating between a solution of the structural analysis using Gss and the soil analysis using Pdisp until convergence of nodal displacements is achieved
Raft analysis is a soil-structure interaction analysis, iterating between a solution of the structural problem and the soil problem until convergence of nodal displacements is achieved. See Raft analysis (Theory) for more information on how GSA iterates for a solution.
When modelling a raft supported on soil some information is needed to clarify how the soil is considered.