The Application Guide shows different ways of defining constraints for these expansion joint assemblies. In some models, the hardware is modeled as restraints with CNodes (page 5-17) and in others, through the expansion joint stiffnesses directly (page 5-24).

Gimballed joints (5-24) have two rotational (bending) degrees of freedom and can be defined without adding restraints. Single hinges (5-17) have only one rotational (bending) degree of freedom so some restraint must be added to lock up the second local bending term defined in the XJ parameters.

Pick a method, use it, then confirm the proper operation of your model by reviewing the results. If your model doesn't respond properly, fix the model.