How to model the post-bending resistance of a brace using steel02 in an SCBF?

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MatiasS
Posts: 3
Joined: Tue Dec 10, 2019 6:41 pm

How to model the post-bending resistance of a brace using steel02 in an SCBF?

Post by MatiasS » Wed Oct 21, 2020 12:43 pm

Hello, I am making a SCBF model based on the example of Vesna, but I have the following question: How can I obtain or how do I have to model the brace to obtain the typical bracing hysteresis with its respective post-bending resistance? When I plot the force-displacement curve (using the same register as the Vesna example) it gives me something similar to the curve of the steel02 material (typical of a system with restricted buckling braces), but without the post-bending resistance of the steel.

For the braces I am using steel02 and implementing uniaxialMaterial Fatigue with an Eo = 0.095 and a m = -0.5

Attached is an image of Black et al. work (1980) of the curve I want to obtain for a circular section.

[img]file:///C:/Users/Matias/Desktop/black.JPG[/img]

selimgunay
Posts: 882
Joined: Mon Sep 09, 2013 8:50 pm
Location: University of California, Berkeley

Re: How to model the post-bending resistance of a brace using steel02 in an SCBF?

Post by selimgunay » Wed Oct 21, 2020 6:49 pm

What do you mean with post-bending resistance here?

MatiasS
Posts: 3
Joined: Tue Dec 10, 2019 6:41 pm

Re: How to model the post-bending resistance of a brace using steel02 in an SCBF?

Post by MatiasS » Wed Oct 21, 2020 7:30 pm

With the residual post-buckling compressive strength. The AISC341-16 establishes it as 30% of the initial compressive strength

selimgunay
Posts: 882
Joined: Mon Sep 09, 2013 8:50 pm
Location: University of California, Berkeley

Re: How to model the post-bending resistance of a brace using steel02 in an SCBF?

Post by selimgunay » Wed Oct 21, 2020 10:40 pm

I see, you can use another material that will allow you to keep the residual post-buckling strength. An example is Hysteretic material, which will maintain the stress at point 3: https://opensees.berkeley.edu/wiki/inde ... c_Material. You can plot the resulting force-deformation and double ehck though

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