Coupling beam and Quad Elements

In this project, I have modeled a double T-beam cross-section with a dummy plate on top. I followed the steps from the Sofistik tutorial for a double T-beam bridge. However, when I calculate the loads, it is clear that the Quad and beam elements are not coupled together.( See the pictures 1)
The solution I found is to couple the edges of the Quad elements with the beam elements using the command for coupling between lines. Now, the problem I encounter is that during superposition, I get a significant rotation in the Quad elements. that effects the whole models

Does anyone have any ideas on how to overcome these problems?
Thank you in advance.

Quads and beam will be coupled only at beam axis. Sagging of the cantiliver will occur. However I can’t see what is happeing at beam’s axis, are quads described on the same nodes?