Pressure thrust in rod-tied bellows

Recently we performed an analysis on a piping system containing an expansion joint with tie rods (in the help file called a 'Tied Bellows Expansion Joint'). More specifically we modeled it using beams and 2point supports (1 tie/link support for each rod, and 2 beams for each tie/link).

During review of the results, we noticed the pressure thrust seemed to cause some additional forces (this was noticed by setting pressure to 0). This seems incorrect because the tie rods should take up this force.
We therefore suspect that when modelling an exp. joint with tie rods, the pressure area should be set to 0. This is how CII (also) does it. Is this correct?

When required we can log a service request, but I first thought to discuss this in general, as it may be of use to others.