Free Field & Lysmer Kuhlemeyer Boundary Condition

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vokumus
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Re: Free Field & Lysmer Kuhlemeyer Boundary Condition

Post by vokumus » Mon Feb 24, 2020 1:06 pm

Thanks for great explanation. I'll try that soon. Best regards.
Vefa OKUMUS
MSc. Structural Engineer
PhD candidate.
Software Developer.
Istanbul - Turkey

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vokumus
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Joined: Thu Nov 14, 2019 7:07 pm

Re: Free Field & Lysmer Kuhlemeyer Boundary Condition

Post by vokumus » Sun Mar 29, 2020 2:35 pm

Hi, I have some more questions about free field boundaries :)

1- In a 2D model, when modeling free field columns, the only thing I changed for the FF element is the thickness of the soil element. For example, my main column soil thickness is 1.00 meter but FF column is 10000 meters to simulate high damping of the "infinite" soil medium. Is it correct?

2-In case of a 3D model it is clear that I won't be able to increase thickness of a solid element. So how to model this? Is it enough to increase the properties of soil material? (bulk modulus, shear modulus etc..)

3. In case of a 3D model, how to connect corner elements? I have read Mr. Petraca's paper about SSI bridge and some other materials from web but information about corner elements are limited. Please see the attached corner.jpg file.

My current 2D model is attached. It would be great if you check my ff boundary conditions. Thanks in advance.
Attachments
FFwBuildings_Double_f01_rigidfoundation.rar
(317.96 KiB) Downloaded 12 times
corner.jpg
corner.jpg (352.09 KiB) Viewed 199 times
Vefa OKUMUS
MSc. Structural Engineer
PhD candidate.
Software Developer.
Istanbul - Turkey

STKO Team
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Joined: Tue Oct 29, 2019 8:45 am

Re: Free Field & Lysmer Kuhlemeyer Boundary Condition

Post by STKO Team » Tue Mar 31, 2020 10:09 am

Dear vokums,
  1. Yes it is correct, in 2D it is sufficient to increase the thickness
  2. Yes in 3D what we did is to increase the material properties. In fact in 2D what the element does is just getting the sigma and tangent tensor from the material and multiply them by the thickness before computing internal forces (-integrate(B^T*Sigma*thickness*dA)) and the stiffness matrix (integrate(B^T * C*thickness * B * dV))
  3. the corner FF should be connected to the soil model with the same dashpots, but not connected to the side FF

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vokumus
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Joined: Thu Nov 14, 2019 7:07 pm

Re: Free Field & Lysmer Kuhlemeyer Boundary Condition

Post by vokumus » Tue Mar 31, 2020 7:40 pm

Thank you very much.
Vefa OKUMUS
MSc. Structural Engineer
PhD candidate.
Software Developer.
Istanbul - Turkey

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