How to Get Section Geometry

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cslotboom
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How to Get Section Geometry

Post by cslotboom » Thu Jun 11, 2020 9:18 pm

I'm wondering if anyone knows of a convenient way to get the section geometry for an element already in a OpenSeesPy model.

I'm working on a few post-processing scripts for OpenSeesPy.
If I knew of a way to get section info about an element, it would be possible to plot thickened elements and do a whole host of other things.

mhscott
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Re: How to Get Section Geometry

Post by mhscott » Tue Jun 23, 2020 7:34 am

There's not an easy way to get the section geometry from a fiber section. You can get the fiber locations and areas and make your best guess from there.
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cslotboom
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Re: How to Get Section Geometry

Post by cslotboom » Fri Jul 03, 2020 12:13 pm

Hey Michael
Thanks for your response.

That makes sense - would that output would be through a recorder command, or is there any output command for fibre locations?
i.e. sectionFiber(eleTag, secNum) = [fibre_x, fibre_y, fibre_z]

What about non-fibre sections/elements?

mhscott
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Re: How to Get Section Geometry

Post by mhscott » Mon Jul 06, 2020 3:08 pm

There isn't a recorder option for the fiber locations and areas, but there could be. Can you create an "issue" at the OpenSees GitHub page?

https://github.com/OpenSees/OpenSees/issues
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mhscott
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Re: How to Get Section Geometry

Post by mhscott » Fri Aug 14, 2020 7:18 pm

Christian,

I see that there's a "fiberData" option for the FiberSection2d and 3d recorders. That should do the trick, except you probably want to get the number of fibers too. I'll add that as a recorder option.

Michael
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cslotboom
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Location: UBC

Re: How to Get Section Geometry

Post by cslotboom » Sun Aug 16, 2020 9:42 pm

Hey Michael,

Thanks for your response on github and here. This works perfectly. I forgot you could use the eleResponse command with additional arguments.
For anyone else reading, the following command will do what I want.

out = op.eleResponse(1, 'section', '1', "fiberData" )

For most non-fiber elements we don't even input section dimensions, so manual input will be required either way to thicken elements.

C.

mhscott
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Re: How to Get Section Geometry

Post by mhscott » Mon Aug 17, 2020 4:52 am

Do you divide the length of the returned vector by 5 in order to get the number of fibers? Seems dangerous :D
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