Hi all,
I'm carrying out a differential deflection analysis in Robot Structural Analysis and have been investigating the effect of semi-rigid beam-to-beam connections on the overall behaviour of the frame.
I modelled the beam-to-beam connections in IDEA StatiCa and extracted the initial rotational stiffness, Sj,ini (kNm/rad). I then applied these values as rotational releases in Robot using elastic rotational springs. This was done for almost all beam-to-beam connections within the frame.
After re-running the analysis, I found that the differential deflections were virtually unchanged from the original baseline model with pinned connections.
To verify that the modelling approach was correct, I created a simple dummy model and tested pinned, semi-rigid and fixed connections. In that model, changing the rotational stiffness produced the expected changes in deflection, which suggests the releases are working correctly.
However, when the same approach is applied to the full frame, there is little to no change in the results. Has anyone come across this before, or can suggest what I should be looking at? I'm trying to understand whether this is a modelling issue, a consequence of the frame behaviour itself, or whether the connection stiffness values are simply not significant enough to influence the global differential deflections.
Thanks!
