Ahmed,
effectively it seems a non-standard lateral expansion joint with expansion and angular possibilities.
strange...

first of all, have you checked the pressure thrust? I read 46.53kN/bar, therefore for 0.85bar the piping arrangement and supports (limit stop or full anchor supports , i suppose)and/or connected equipment must are designed for about 4000kg of thust force deriving from this expansion joint.
uncontrolled pressure thrust could be very very dangerous, expecially when the designer does not expect fot it...

then, for my point of view, you can model as a normal tied lateral expansion joint, making a complete model with tie rods, and leaving +-30mm gap on one side.