Brick Elements

[kgkoktsi]

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]

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

[vesna]

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

[gerber]

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]

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

[gerber]

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

[vesna]

It has 8 Gauss points.

[zanakarimi]

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

[fmk]

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]

the node numbering is as per their other element


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

[zanakarimi]

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]

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]

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]

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]

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

Regards,

Wilson