Example for Lysmer+free field boundary model

[yuweihwang]

Hello,

I saw ASDEA demonstrated the Lysmer+free field boundary model in your youtube video
(https://youtu.be/0BTug_4or6g?t=109)
Is there any tutorial or can you provide the scd file of this example for us to learn how to implement this boundary?

Thanks for your help,
Yu-Wei Hwang

[STKO Team]

Hi Yu-Wei,

That example is quite old, I don't have that exact SCD file anymore. However we recently gave a webinar about SSI with absorbing boundaries which is exactly the same, but more generic (it is a 3D example)

On our website you can visit the e-learning wepage were we keep track of all previous webinars with links to the video recordings and to download the input files:

https://asdeasoft.net/?stkowebinars-for-opensees

ssi.png (61.61 KiB) Viewed 1696 times

If you instead need exactly that 2D example, I could replicated it as soon as possible.

[yuweihwang]

Hello,
Thank you for your information. It will be really nice if we can have a demo for 2D model!
Thank you for all your help!

[STKO Team]

dear User,
of course, we will prepare it.
Have a nice day

[yuweihwang]

Thank you!!

[Clarabella]

Dear Yu-Wei,
please dowload Vukkumus' model modified by STKO:
viewtopic.php?f=36&t=1662#p2134

[vokumus]

Dear Yu-Wei,
please dowload Vukkumus' model modified by STKO:
viewtopic.php?f=36&t=1662#p2134

Dear Clarabella and Yu-Wei;

In this model, there was some strange results. For example dynamic analysis starts with very high accelerations. I have managed to get correct results making loadconst selected and psuedo time zero in relax analysis after the initial stage analysis.

I don't know why this happened. I couldn't run OpenSeesMP in my computer and changed some analysis parameters to use normal OpenSees. It does not make sense but maybe this could be the culprit.

Anyway, model is working fine now.

[Clarabella]

Dear Vokumus,
we usually add an analysis after the vertical analysis, in particular when we perform nonlinear TH. Just add an analysis with damping to be sure to not have spurious accerelation before starting the TH, this is a suggestion both for implicit and explicit analysis and it does not depend on the software used.
Regards

[vokumus]

Dear Vokumus,
we usually add an analysis after the vertical analysis, in particular when we perform nonlinear TH. Just add an analysis with damping to be sure to not have spurious accerelation before starting the TH, this is a suggestion both for implicit and explicit analysis and it does not depend on the software used.
Regards

Yes I know. But the problem is; if you don't select loadconst and pseudo time = 0 for this relaxation analysis you mentioned, you get some weird results in TH analysis.

[Clarabella]

Yes, you are perfectly right the load must be constant and you need to set to 0 the pseudo time.