Masonry Prism Test

[kesavapraba]

Dear Sir/Madam
I have modeled the usual prism test on masonry brick and mortar joint assembly (5 bricks + 4 joints) using stdBrick element and DamageTC3D material. I want to maintain the top face of the prism move only along the axis of the prism. Can you please suggest me the BCs which should be used to achieve it? I hereby attach the prepared model. Thank you.

[Clarabella]

Could you post the test setup? Or at least a diagram with what you like to model

[kesavapraba]

Dear Sir/Madam
Thank you for your reply. I hereby attach the test setup and a youtube video link for your reference.
https://www.youtube.com/watch?v=x4XcqWvF9vA

[STKO Team]

You can simply fix Ux and Uz, while Uy will be free of moving.
In your model you applied a force and performed a displacement control.

But in this simple model it's even easier to apply an imposed displacement and perform a load control, as I did in the attached file

PrismTest.zip

(768.26 KiB) Downloaded 350 times

Then I changed the stdBrick to the bbarBrick, which is much more performant and gives the same failure pattern given by the quadratic element.

Finally, you need a finer mesh to capture the splitting in bricks due to the expansion of masonry. So I set up your model for parallel analysis.
To speed up the calculation I took advantage of 2 planes of symmetry. I modeled only 1 quarter of your model.
With parallel OpenSeesMP and 6 processors, it took only 5 minutes.

brick.png (167.89 KiB) Viewed 4726 times

[kesavapraba]

Dear Sir/Madam
Thanks a lot for the model and clarification. I would like to ask following questions regarding the BCs that you applied on the model:
1) In FixBottom condition only 3D->U has been used, whereas in FixTop condition 3D-> U-R has been selected. Any specific reason for that? Will it make any difference if I apply 3D-> U with Ux and Uz fixed for FixTop condition?

2) In FixBottom condition only Ux, Uy and Uz are fixed. How do you ensure that the rotations also fixed there? I mean how the entire face at the bottom is fixed in your model by just fixing Ux, Uy and Uz only?

[STKO Team]

1) In FixBottom condition only 3D->U has been used, whereas in FixTop condition 3D-> U-R has been selected. Any specific reason for that? Will it make any difference if I apply 3D-> U with Ux and Uz fixed for FixTop condition?

I forgot to convert it to 3D-U. But it makes no difference because solid elements do not have rotational DOFs.
In fact, I removed the shells that you placed at the top and bottom because there is no need to use them because they will fixed anyway.

2) In FixBottom condition only Ux, Uy and Uz are fixed. How do you ensure that the rotations also fixed there? I mean how the entire face at the bottom is fixed in your model by just fixing Ux, Uy and Uz only?

A solid element does not have rotational DOFs.
The overall rigid body rotation will be constrained because multiple nodes are fixed: A face can undergo rigid body rotation only if opposite nodes (with respect to the center) can have opposite displacements.

[kesavapraba]

Dear Sir/Madam
Thanks again for the clarification. I got your points. Sincerely appreciate your timely response.

[Clarabella]

Dear Kesavapraba,
we are glad we solved the problem.
Regards