Underground structures

[shuaicai]

skamalzare wrote:
> - Yes, they should be at same place. Otherwise, you will receive an error
> that the length of zerolength element is beyond tolerance.
>
> - ZeroLength elements need nodes with same NUMBER of DOFs at both ends. I
> guess, as long as both soil and structure nodes have same number of DOFs,
> you should be able to connect them with zerolength elements.
>
> Bests,
> Soheil


In my model, quadup elements are used for soil material, and quad for underground structure, that is obviously different in Dofs for two nodes of zerolength element? How to solve this problem?

[skamalzare]

Simply define pseudo 3 DOF nodes at place of your 2 DOF structural nodes. Then tie these nodes together with periodic connection (i.e equalDOF), and make the pseudo node to be the slave.
Now you can connect the 3 DOF pseudo node to 3 DOF soil node with a zerolength element.

[shuaicai]

skamalzare wrote:
> Simply define pseudo 3 DOF nodes at place of your 2 DOF structural nodes.
> Then tie these nodes together with periodic connection (i.e equalDOF), and
> make the pseudo node to be the slave.
> Now you can connect the 3 DOF pseudo node to 3 DOF soil node with a
> zerolength element.



When freefield model computed, I found a problem, the element size is set as 0.01m, the result worked out is not correct obviously, unless the element size set as 1m or larger, the the result worked out is correct and better, May I ask how is this going? Thank you! Cheng Xuelei.

[shuaicai]

Underground structures are created by dispBeamColumn element in my model, plane strain problem, bending moment and stress， strain of element can be recorded, but if I want to obtain shear force and axial force of this element , how to transform data recordered ?

[skamalzare]

Hi Shuaicai,

Try using the following command to record the global forces from your beam elements:

recorder Element -file BeamGlobalForces.out -time -dT $dTRecording -ele $BeamElementList globalForce

In 2D conditions, this recorder will give you: Fx Fy Mz
In 3D conditions, this recorder will give you: Fx Fy Fz Mx My Mz

In another note, please try to open new discussions within new topics. This can help others to follow your questions.

Bests,
Soheil

[shuaicai]

francisconazar wrote:
> Dear Soheil,
>
> I'm currently modelling a tunnel subjected to an ovalling deformation and
> so far the zerolengthContact elements work fine (for now, static analysis),
> nevertheless, I'm interested in knowing how to extend the use of p-y and
> t-z springs to this problem, in case I decide to extend the model to
> dynamic analysis and encounter your problem of convergence. I have 2
> questions that maybe you can help me answer:
>
> 1. My structure is basically a linear tunnel and not a pile, so I don't
> know if I can just use them directly since I believe the q-z spring
> incorporate friction along a diameter of the pile, and in this problem
> there is no diameter, just a 'wall' (lining).
> 2. Do you know any references for the curve parameters (pu, ymax) for other
> soils (e.g., gravelly soils) ? I'm having a hard time searching for the
> values to use.
>
> Thanks,
> Regards.


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