CAESAR II will give correct result but the modelling has to be right. The problem is that to have axial movement requires anchors on both sides of the expansion joint. Using limit stops is just an emergency safety mechanism if one of the anchors fail. Typically such is done with rods and nuts with gaps or slotted hinges.

It is impossible to design such design to work during the operation without having the pressure thrust on the anchors. Anchors can be steel structures, pumps, vessels etc. but most of the time the forces are too high. I have a case where partially buried concrete block about 1 m^3 moved on NB600/6 bar line.

Unrestrained axial expansion joint is a dangerous item. Nearly every time where such is used the pipe design is poor or bad or even dangerous.