Reaction forces from anchors on steel plate to concrete connection

General Questions
1

Hello,

I am having a problem reading the forces from the anchors in my projects where I am trying to create a steel plate to concrete connection.
Probably the problem is with my boundary conditions or with my understanding of some functions. I tried to do it myself, but I have no more ideas what to do and I have decided to ask there.
I have prepared two designs:

  • In the first one I modeled the anchors as a cylinders. They are fixed from the bottom and also on the surface where they meet the holes. I also used Compression_Only constrain to mimic a concrete slab. I used the History Outputs to look for the reaction forces. If I apply only tension load, then there shouldn’t be any high horizontal reaction forces, but here they are. I suppose that there is some problem with my boundary conditions, but I couldn’t find out what’s wrong.

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    image1901×786 212 KB

    Attempt1.pmx (7.3 MB)

  • In the second one I used Point springs to mimic the anchors and history output to look for the reaction forces. There is a different problem, because there are not reaction forces at all. Only some small numbers like 0,0001N.

    image
    image1892×787 213 KB

    Attempt2.pmx (6.4 MB)

These are not my only attempts to solve my problem, but these were the best so far. I searched a couple dozen posts here to find answers, but all of that lead me here.
I would like you to ask if can you show me what am I doing wrong in my designs. Or maybe do you have another solution that could allow me to read these reaction forces from the anchors correctly.

I will be greatly grateful if someone could help me with this. Thank you.

2

First of all, you can get meaningful reaction forces only for the nodes and DOFs (directions) where boundary conditions are applied and possibly, there are no external forces.

For the first approach, instead of fixing the top parts of the columns, you can tie them to the plate there and only fix their bottom faces, requesting RF history output for them.

Attempt1-mod.pmx (5.3 MB)