Brick Elements

Forum for OpenSees users to post questions, comments, etc. on the use of the OpenSees interpreter, OpenSees.exe

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kgkoktsi
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Location: City University London

Brick Elements

Post by kgkoktsi » Sun Aug 05, 2012 2:12 am

Hi!
I have simulated a structure with brick8N elements by using a model BasicBuilder -ndm 3 -ndf 3. But, when I try to run the script, it posts a warning message: "WARNING NDM=3 and NDF=3 is incompatible with available frame elements". Just to notice that the only type of elements I have used is the one mentioned, the brick8N elements. Does anybody know what the problem is?
The second problem I'm dealing with has to do with the geometric Transformation of these elements. As the x,y,z are global axis, is the definition "geomTransf Linear 1;" sufficient?
Thanks!

gerber
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Location: National Technical University of Athens

Re: Brick Elements

Post by gerber » Sun Aug 05, 2012 9:53 am

When you use brick elements you don`t define geometric transformation by this command.
This command is used for frame transformation.

vesna
Posts: 3033
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Location: UC Berkeley

Re: Brick Elements

Post by vesna » Mon Aug 06, 2012 2:09 pm

Brick8N is removed from OpenSees and that is probably why you got the warning messages. Use stdBrick instead.

gerber
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Location: National Technical University of Athens

Re: Brick Elements

Post by gerber » Sat Aug 18, 2012 10:06 am

I use brick elements in my model and I wonder if there is a command which can divide a big brick element into small bricks elements.
Something like mesh command...

vesna
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Location: UC Berkeley

Re: Brick Elements

Post by vesna » Mon Aug 20, 2012 3:46 pm

Block3D command should help with this:
http://opensees.berkeley.edu/wiki/index ... 3D_Command

gerber
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Location: National Technical University of Athens

Re: Brick Elements

Post by gerber » Thu Oct 04, 2012 12:47 pm

Does anybody know how many Gauss points has a standard brick element?

vesna
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Location: UC Berkeley

Re: Brick Elements

Post by vesna » Thu Oct 04, 2012 4:07 pm

It has 8 Gauss points.

zanakarimi
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Re: Brick Elements

Post by zanakarimi » Fri Apr 05, 2013 1:57 am

Hi everybody,
Is Brick20N element removed from OpenSees? If the answer is positive, which element do you recommend?
Thanks,

fmk
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Re: Brick Elements

Post by fmk » Mon Apr 08, 2013 8:56 am

it was removed. there is a "20NodeBrick" you can use. i am just checking with the author or the node numbering, which i suspect it is different to the previous.

fmk
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Re: Brick Elements

Post by fmk » Mon Apr 08, 2013 12:58 pm

the node numbering is as per their other element


http://opensees.berkeley.edu/wiki/index ... -p_Element

zanakarimi
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Re: Brick Elements

Post by zanakarimi » Sat Apr 13, 2013 10:56 am

Thanks for your response,
20_8Brick_UP is for soil and porous media. Can I use it for solid (steel) with appropriate combined bulk modulus?
Thanks again,

fmk
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Re: Brick Elements

Post by fmk » Mon Apr 15, 2013 2:21 pm

you could. i only showed you that page so that you would see the node numbering! as mentioned use the 20NodeBrick.
element 20NodeBrick eleTag node1? ... node20? matTag? <b1? b2? b3?>

wilberk
Posts: 13
Joined: Mon Jul 16, 2012 6:58 pm
Location: Pontificia Universidad Católica de Chile

Re: Brick Elements

Post by wilberk » Tue Apr 21, 2015 4:26 pm

Hi everybody, Please I have 2 questions. First, Is the 20NodeBrick available now?, and,

Then, is it possible to degenerate this element in a quadratic tetrahedron? like the stdBrick.

Thanks,

Wilson

fmk
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Re: Brick Elements

Post by fmk » Wed Apr 22, 2015 10:29 am

the brick is available

no, in general you cannot degenerate a higher order element by collapsing the nodes w/o modiying the interpolation functions. see some books on the FEM, e.g. Bathe Sec 5.3

wilberk
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Location: Pontificia Universidad Católica de Chile

Re: Brick Elements

Post by wilberk » Thu Apr 23, 2015 8:52 am

Thank you very much Frank. Is it possible to generate quadratic tertrahedrons in opensees in any way?

Regards,

Wilson

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