Seismosoft | Earthquake Engineering Solutions

I have introduced a rotational spring at the Beam-Column Joint panel based on a particular constitutive law (e.g. Moment-Rotation Law) and i'm trying to check the rotation of the spring achieved at a particular stage with the "Perfomance Criteria" -------> "Non Frame Elements". Can anyone tell me how the software calculates the rotation in a no-dimensional link element (wich represents the Joint Rotational Spring)?. This because i have no corrispondence at a certain step between the rotation value calculated automatically by the software and the rotation value calculated manually, using the joint nodal displacements.
NB: The Joint Core region is modeled by rigid frame elements connected by a rotational spring.
Best Regards

The quantity checked by the Perfomance Criteria is the internal link deformation, translational or rotational.
In your case the rotation is the difference in the rotation between the two nodes, these rotations are connected with the rotational DOFs of the link element.
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