asdeasoft.net

Hi STKO Team and Forum,

I hope you are all doing well.

I’m opening this thread to kindly ask for your assistance in resolving an issue I’m encountering with the use of the PDMY material in an SSI model. Below, I’ve attached my model along with the corresponding error message.

To model the soil, I’m using SSPQuad elements, zeroLengthContactASDImplex, ASDAbsorbingBoundary and the InitialState material wrapper.

For this, I have included both auxiliary analyses required when using InitialStateAnalysis OFF and UpdateMaterialStage -stage 1, following the guidelines provided in previous threads and webinars.

Regarding the issue, I’ve read through the forum and, as far as I understand, there should be no problem using UpdateMaterialStage in combination with SSPQuad elements. However, OpenSees returns an error stating that it is not possible to update the stage of my materials.

Could this issue be related to something else—perhaps one of the analysis steps I’m running?

Additionally, I’m currently treating all gravity load steps as transient analyses, but for example, in STAGE3 (Settlement Analysis), there are some spurious accelerations concentrated in the structure, which then, in STAGE4 (Transition to Plastic Analysis), are eliminated. But my question is, since I'm modelling the superstructure using MVLEM with nonlinear materials for Concrete and Steel (further to be changed to SteelMPF and Concrete02/CM), this spurious accelerations generate damage in the materials? In that case, how can I fix this?

I would greatly appreciate any guidance or suggestions you may have on this matter.

Best regards

Update on the Issue:

Hi STKO,

I'm posting this reply to let you know that I was able to resolve both issues mentioned earlier in this thread. After several iterations adjusting the order of my analysis steps, I was finally able to obtain results that are consistent with my expectations.

According to what I reviewed in previous forum posts, the issue I mentioned earlier — where the material stages were not being updated — was actually due to the use of multiple partitions in my model with OpenSeesMP. I confirmed this by running a single-processor analysis, where the material was indeed correctly updated to the plastic stage.

As for the issue with spurious accelerations, I was able to resolve it by applying all gravity analyses as static, instead of transient as I was doing before.

I still appreciate any suggestions or comments you may have. I’ll attach the order of my analysis steps at the end of this reply in case someone spots any inconsistency.

Best regards,
tomfrdnz

We're glad you solved it.
Yes, the warning is because when you partition your model, some partition may not have all the materials you are trying to update (because they are only on other partitions), thus the warning.


Regarding the accelerations in gravity analyses, one way to solve it is how you did it, i.e. do a static analysis.
However, this approach does not work with U-P elements. In that case you must use transient analyses. in such cases you can simulate a pseudo static analysis just by doing a "slow" dynamic analysis (i.e. using large time steps)