Soil-Pile Interaction Modeling

[kolozvari]

Ok. Thank you.

[STKO Team]

You're welcome

[kolozvari]

Hello,

I am trying to analyze two blocks placed side by side with the ASD interaction in between.

Capture.JPG (25.22 KiB) Viewed 4984 times

I want to first apply gravity load and then push one of the blocks upward as explained in the figure below.

Capture2.JPG (5.73 KiB) Viewed 4984 times

After the application of gravity load there should be some friction between the solid elements.

However, I am pretty sure I didn't define my analysis steps correctly. I first apply fixed supports at the base of both elements and then I remove the supports only underneath one of them (the right one) after the application of gravity load. However, this doesn't seem to work. Can you please advise how to do this?

I have attached the model as well for your convenience.

Looking forward to hearing from you. Thank you.

[STKO Team]

I see some problems here:

• The contact normal vector should be the global X axis, but you did not assign any local axes to the interaction, so the contact will not work, since the default contact vector will be Z (without a local axes)
• When you remove the fix at the right block and apply a load, the right block will be singular (I replaced the pressure on top with an imposed disp at the bottom face, applied after the fix is removed)
• Accidentally you selected also the right edge of the left bottom face in the fixbottomR condition, so when you remove it also the left face will start being singular in rotation about the Y axis
• Now it works but I'm confused about the monitor.
• The stiffness of the contact should be higher then the stiffness of the block (E*size_block)

If you really want to test the behavior of contact (shear force-displacement under a certain normal pressure) this is not the right benchmark (the pressure should be normal to the contact sliding plane).
See our webinar on contact, there are some benchmark there similar to what you are doing here. But with one block on top of another

[kolozvari]

Hello,

Thank you very much! Could you please remove the file from the forum? Also...

The contact normal vector should be the global X axis, but you did not assign any local axes to the interaction, so the contact will not work, since the default contact vector will be Z (without a local axes)

This is my mistake, I apologize.

When you remove the fix at the right block and apply a load, the right block will be singular (I replaced the pressure on top with an imposed disp at the bottom face, applied after the fix is removed)

Thanks, I will look into this and follow up if I have more questions.

Accidentally you selected also the right edge of the left bottom face in the fixbottomR condition, so when you remove it also the left face will start being singular in rotation about the Y axis

For some reason I couldnt select the face only. I remember struggling with this. It is strange because I was able to do it for the left block.

Now it works but I'm confused about the monitor.

The monitor was not finalized. Thank you for noticing.

The stiffness of the contact should be higher then the stiffness of the block (E*size_block)

OK, thank you.

Thank you very much for your help!

[STKO Team]

Done

[kolozvari]

Hello,

I am modeling a full SSI problem with a frame building, pile foundation and a soil domain. This is the same building model from "Issue with Modal Analysis of a Frame Building" thread. The model is quite complex with complex pile geometry, contact elements, and soil layers. When I ran the model, the analysis is blowing up, as you can see from the deformed shape below.

BLowingup.JPG (147.48 KiB) Viewed 4846 times

Can you please take a look at the model and let me know if anything stands out? Also, any suggestion on how to tackle this problem would be useful.

Here is the model for your convenience.



Thank you very much.

[kolozvari]

It appears that using stdBrick instead of sspBrick resolved the issue. Thanks

[STKO Team]

Yes I was going to answer just now.
When you see a hourglass-like deformation pattern is (almost) always due to under-integrated elements and the propagation of spurious zero-energy modes (for this reason called hourglass modes)