Is this correct way to get a fixed-fixed connection?

[cagosi4788]

I have two big plates, and inbetween there is a smaller plate connecting the two bigger plates. I want the small plate to be fixed to both sides, and was wondering if I have done it correctly as seen in the attached picture?

I ask because I am working on a model someone else made, and their definition of fixed does not match what I think fixed end should be (displacement and rotations fully restricted). 

[Rafacascudo]

Completely wrong. That full released bar on both ends will give you lots of instabilities warnings and results will be wrong.

Model the small plate also as a panel or at least as a non released bar with full rigid links from bar end nodes to big plate nodes within bar width

[Krzysztof_Wasik]

Hi @cagosi4788 

Release defined in your model has all defress of freedom free.

In your case small plate is simulated by beam. Remove release from beam (default beam /slab connection is fixed, no need for release definition).

To avoid stress concentration in slab/beam connection point I would recommend to connect each beam endnode with neighbouring slab nodes using rigid links. It will transfer force from beam to slab edge segment corresponding to beam width

[cagosi4788]

Thank you for the reply Krystof; have I fixed the beam to be fixed-fixed now? 

In reality the bar is supposed to be a small plate that has been bolted underneath the two plates. Its supposed to prevent horizontal movement of the two bigger plates. I am not sure if it needs to be fixed-fixed, or fixed-pinned?

[cagosi4788]

I seem to have misread how the connection works Rafacascudo. You seem knowledgeable at this topic, if I may also ask; In reality the bar is supposed to be a small plate that has been bolted underneath the two plates. Its supposed to prevent horizontal movement of the two bigger plates. I am not sure if it needs to be fixed-fixed, fixed-pinned or some other type of connection?

[Krzysztof_Wasik]

Hi @cagosi4788 

If small plate is supposed to prevent horizontal movement I would use pinned pinned connection (in vertical plane). Small plate will not transfer significant bending moment if it is bolted like on the picture

[cagosi4788]

Do you think there might be some instability issues if we dont fix one side? And if it is expected to carry some moment, do you think fixed-fixed or fixed-pinned could be a good idea? Would be hard to know which side to pin though...

[Krzysztof_Wasik]

HI @cagosi4788 

I see only model part with mo supports and other connected members. I cannot sayif releases will cause instabilities. You can just run calculation and check with different releases setting.