I have a steel structure modeled by 1D beams that I want to bolt plates to, which are represented by 2D shells. I am not sure what is the best way to model this connection. I have tried to do a kinematic constraint between the two using a reference point, but it seems to add artificial stiffness to the model. There is deformation in the beams that the constraint seems to eliminate.

Here is picture of a smaller model to get an idea of what I'm trying to accomplish. How should I constrain the 2D shell (beige) to the 1D beams (green)? Thanks in advance.