Regarding Absorbing boundary result

[begumemte1991]

Dear team STKO,

The file which is there on your website for 2D soil model validation under the application of ricker wavelet does not give the same result as shown in the webinar available on YouTube. Can you please confirm why is it happening so?

Results from the monitor defined are attached herewith. Also, in the post-processor, it was found that the wave does not reach the surface.

[STKO Team]

I think it's due to a recent change in OpenSees. Now it seems that the Linear algorithm with -factorOnce does not work with the TRBDF2 integrator.

Can you confirm that you are using this combination?

You can either switch-off the -factorOnce option, or use another integrator Like Newmark 0.5 0.25

[begumemte1991]

Yeah, now it is working perfectly fine. I have used Newmark 0.5 0.25. Thank You.

[STKO Team]

You're welcome

[begumemte1991]

Hello team STKO,

As it is known to us that STKO's automated LK boundaries automatically identify the bottom and side boundaries. Since the bedrock shear-wave velocity and density are much higher than the soil, and the material for LK boundaries is defined only for soil, I wanted to know how STKO is applying motion at the bottom. Does the motion get multiplied with the soil properties or STKO has the ability to consider some bedrock properties and multiply with those properties? Because so far as I know if soil properties are used in converting the acceleration to equivalent forces, the results will not be correct.

[begumemte1991]

Please reply to my query. Thank you.

[HC2020]

Hi Begum,
Sorry for the wait, we have been closed for holidays for the last two weeks.
We will be answering the queries over the next few days.
Thanks for your patience.

[STKO Team]

As it is known to us that STKO's automated LK boundaries automatically identify the bottom and side boundaries. Since the bedrock shear-wave velocity and density are much higher than the soil, and the material for LK boundaries is defined only for soil, I wanted to know how STKO is applying motion at the bottom. Does the motion get multiplied with the soil properties or STKO has the ability to consider some bedrock properties and multiply with those properties? Because so far as I know if soil properties are used in converting the acceleration to equivalent forces, the results will not be correct.

If at the bottom interface you have bedrock, just create 2 ASDAbsorbingBoundaryMaterials, one with the soil properties (sides) and one with the bedrock properties (bottom)

[begumemte1991]

Thank you for your reply.

If at the bottom interface you have bedrock, just create 2 ASDAbsorbingBoundaryMaterials, one with the soil properties (sides) and one with the bedrock properties (bottom)

Ok, I will do it.

We are planning to update the source code of the ASDAbsorbingBoundary in OpenSees such that you can assign a real material model, instead of G,v and rho. In this way you will be able to directly assign the same material you assign to the interior soil domain.

From the above discussion, I could learn many things. Also as discussed here, for nonlinear soil material are you planning to develop nonlinear absorbing boundaries? If yes, can you please give the tentative date as to when it is going to release? Also, I would request STKO for another webinar on this (considering the nonlinearity of soil like using PDMY material and nonlinear absorbing boundaries).

[STKO Team]

From the above discussion, I could learn many things. Also as discussed here, for nonlinear soil material are you planning to develop nonlinear absorbing boundaries?

Yes

If yes, can you please give the tentative date as to when it is going to release?

I cannot give you a real date, but I hope during September

Also, I would request STKO for another webinar on this (considering the nonlinearity of soil like using PDMY material and nonlinear absorbing boundaries).

Sure, we will do it