Thanks Michael for your response.

I just want to know that

1. You mentioned that Check with manufacturer. x with gap does not have a stiffness - or rather, it has unlimited stiffness........
I think that the bellow stiffness in axial direction will take care.Right?

2. pressure thrust effect at the centre of the expansion joint and simulation of the weight of the centre spool at pantograph gimbal location...Whether i need to consider any axial restraint with cnode at the centre also.