Best element for handling axial load and biaxial bending?

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epsilon
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Best element for handling axial load and biaxial bending?

Post by epsilon » Mon Nov 28, 2022 9:59 pm

Hi,
I need to analyze a structure consist of armed concrete beam and columns (say for example single span single level frame at simplest form)
Need static nonlinear (both material and geometrical non-linearity) analysis .
I'm aware of fiber element, which could be used to model material non-linearity. is there any other 1D element which can be used to model material non-linearity of concrete beam or column? note that to reduce computation cost, I rather to reduce DoFs by use of 1d elements (like beam column) instead of 2d (like shell) or 3d (like brick).

Thanks

mhscott
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Re: Best element for handling axial load and biaxial bending?

Post by mhscott » Tue Nov 29, 2022 4:30 am

You don't have to use fiber sections. You can, for example, use a section aggregator inside a force-based element.
https://portwooddigital.com/2021/07/04/ ... ggregated/

epsilon
Posts: 9
Joined: Sat Aug 26, 2017 5:44 am
Location: NA

Re: Best element for handling axial load and biaxial bending?

Post by epsilon » Tue Dec 06, 2022 7:29 am

mhscott wrote:
Tue Nov 29, 2022 4:30 am
You don't have to use fiber sections. You can, for example, use a section aggregator inside a force-based element.
https://portwooddigital.com/2021/07/04/ ... ggregated/
Hello,
Thank you for the link.
I just interest in static analysis, so I think i do not need hysteresis as in the link. What i do need right no is taking the interaction of axial load and biaxial bending into account for analysis. the Euler hypothesis about beams which plane sections remain plane. and also uniaxial material.
For example this simple case:

Image
L = 3m and P = 10kN

and this section

Image

with steel and concrete with the uniaxial non-linear material:

Image

Image

So what other element expect fiber element i can use for this purpose?

There is loading, but there is NO unloading, so material stress-strain curve is NOT depended to loading

Thanks in advanced

mhscott
Posts: 868
Joined: Tue Jul 06, 2004 3:38 pm
Location: Corvallis, Oregon USA
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Re: Best element for handling axial load and biaxial bending?

Post by mhscott » Thu Jan 12, 2023 7:14 am

The section aggregator is not limited to cyclic loading (nothing in OpenSees is). You can use the aggregator shown in the link for monotonic loading too.

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