Hi Nala
You don’t have to model a reinforced pad in caesar. You just have to take proper SIF for that. Click sif/tee at that node. From drop menu of dialogue box select type “ reinforced” & put the value of pad thickness.
Effective ID of expansion bellow use to calculate pressure thrust for bellow. Vendor will supply that data in terms of effective ID or effective area.
In caesar any dialogue box just press F1 you will get information for that.
I suggest before using a expansion bellow please read EJMA ( Expansion joints manufacturer association ).