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Hello,

I have reviewed the tutorial for SSI, and tried to implement the Lysmer boundary in my model (as attached).
However, It cannot work every time when I tried to update the material to the plastic stage.
Can we use the same method that showed in the tutorial to 20-8BrickUP element with nonlinear material? or will it is because I use gravity loading (transient analysis) to simulate the correct stress state rather than using body force?
Will it possible for you to take a look at my file? I will appreciate any suggestions.

Many thanks,

Dear YuWei,
Just to make sure it is not due to the LK boundaries, I tried to make the materials "plastic" since from the very beginning (here the model is still fixed without LK).
And also here it was not converging (actually OpenSees was stuck, probably in some long iteration loop inside the PDY02 material).
So I tried to lower the vertical loads. First I removed the Bz(=-9.81) parameter from the brick elements because the self weight in the elements are applied instantaneously. Then I lowered the loads in first loadPatter using a -factor = 0.01.
In that case the analysis started. Then I tried to increase it up to 0.1. And then it was still stuck.

So what I think is that you need to make sure your material parameters and/or loadings are correct. It seems it cannot even bear its own self-weight