Mostafa Ragab

Make a DXF file for walls , columns and shear walls and export it to CSI safe and then choose them all and go to Assign menu , define slab section and choose it's type as stiff from ( slab type options ) and give them the same raft thickness . After that you can export raft , then load from etabs and run the model .

When you model the raft on safe , you have to export walls ,shear walls and columns to the model and define them as stiff areas with depths equal to raft thickness to distribute point and line loads on areas and that decreases the stress concentration under the wall .