Define simple-support boundary condition of a beam (Solid Mechanics)

Hello everyone,

I am a new Comsol user and through the past few months I have made simple models comparing the results with some theoretical models.

I will bother you with plenty of questions the next days(haha), and here is the first one:

I know till now that if we want to have a beam clamped or free we simply choose the edge and make it fixed constraint or free respectively.

Now if we need a simply-supported BC, how could we make that?
(I chose fixed constraint point and prescribed displacement=0 at a point and the results are pretty much the same but they does not match the theoretical ones.

hope to have nice conversations here,
Tsagarakis Nicolas