Earth pressure along basement wall

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BuuNguyen
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Earth pressure along basement wall

Post by BuuNguyen » Mon Jun 20, 2022 5:36 am

Hi STKO team,
I am modeling SSI with basement wall. How can I extract earth pressure along the basement wall?
I tried to extract horizontal soil stress along the wall, but it is impossible when using SSPBrickUP element for soil?
I used shell element for wall.
Thank you in advance.
Buu

STKO Team
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Re: Earth pressure along basement wall

Post by STKO Team » Tue Jun 21, 2022 4:23 pm

What do you mean by "impossible when using SSPBrickUP"?

BuuNguyen
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Re: Earth pressure along basement wall

Post by BuuNguyen » Fri Aug 05, 2022 5:28 am

Hi STKO team,

I used Python API code you suggest as in this post (viewtopic.php?f=46&t=2179) to extract earth pressure on basement wall. I extract component 2 (index: 1) in volume stress-7 components
However, I got a weird result as in attached figure. The lateral earth pressure at the point near ground surface increased with increasing of structural loading, and significant larger than at-rest pressure

Do you know any possible problems in this result?
Thank you
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BuuNguyen
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Re: Earth pressure along basement wall

Post by BuuNguyen » Sun Aug 07, 2022 6:50 am

Hi STKO team,
I found that there were some horizontal displacement during stage 4 (application of structural load) as in attached figure.
it seems to be the reason causing the earth pressure increase as I mentioned above?
How can I eliminate the horizontal displacement during structural load application?
Thank you
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STKO Team
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Re: Earth pressure along basement wall

Post by STKO Team » Mon Aug 22, 2022 11:20 am

I don't think you can remove them, it's a sort of Poisson effect, They should be also in the X direction.
It's normal. You have just to make sure it has a meaningful value. Also, you should try to see if the size of the reduced domain is affecting this. Try with a larger soil portion in the X and Y directions

BuuNguyen
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Re: Earth pressure along basement wall

Post by BuuNguyen » Tue Aug 23, 2022 7:53 am

It seems due to the wrong soil-wall contact. I changed the soil as slave, wall as master, then the result seems reasonable.
One more problem: I used ASDAutoBoundary to apply EQ and used PDMY material, SSP brickUP element for soil, during shaking the center of soil domain move upwards, while the edges move downwards as shown in the attached figure. Is there any possible problem in boundary condition?
It seems due to dilation of soil, but when I changed the soil parameter to Loose sand, I got same results

Thank you for your time.
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STKO Team
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Re: Earth pressure along basement wall

Post by STKO Team » Fri Aug 26, 2022 8:18 am

Could you try to keep the PDMY state ELASTIC? If it does not create the issue, it means that it is due to the strong nonlinearity generated by the material (remember that the absorbing boundaries assumes a linear elastic behavior, but we are currently working on extending them to the nonlinear behavior)

Same issue here:
viewtopic.php?f=36&t=2335

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