Bending moments along members in IDEA StatiCa Connection are simplified as linear, beginning from the moment value inputted in the load effects tab and propagating as a linear function of inputted shear force towards the member free end.
In the tab of load effects, you input the nodal internal forces, which you obtain from the results of structural analysis of the designed structure.
IDEA StatiCa Connection is by default designed to analyze and code-check joint models consisting of one structural node. To avoid mistakes, keep the connection models simple and avoid creating large complex models consisting of more structural nodes.
Also, make sure you input all the internal forces correctly and keep the loads are in equilibrium, as this is a must by law of statics when treating structural nodes.