Non-bonded segment

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junruli
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Joined: Thu Jan 15, 2026 1:10 am

Non-bonded segment

Post by junruli » Thu Jan 15, 2026 1:52 am

Hello,

I am modeling a reinforced concrete beam-column joint and need to create an unbonded zone in a part of the beam, but I don't know how to establish it. If you have any advice, I would be grateful.

STKO Team
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Re: Non-bonded segment

Post by STKO Team » Fri Jan 23, 2026 8:59 am

What do you mean by "unbonded zone" ?

junruli
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Joined: Thu Jan 15, 2026 1:10 am

Re: Non-bonded segment

Post by junruli » Mon Jan 26, 2026 6:08 am

Concrete is not in contact with the reinforcing steel.

junruli
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Joined: Thu Jan 15, 2026 1:10 am

Re: Non-bonded segment

Post by junruli » Mon Jan 26, 2026 6:12 am

STKO Team wrote:
Fri Jan 23, 2026 8:59 am
What do you mean by "unbonded zone" ?
Concrete is not in contact with the reinforcing steel.

junruli
Posts: 9
Joined: Thu Jan 15, 2026 1:10 am

Re: Non-bonded segment

Post by junruli » Tue Jan 27, 2026 3:18 am

It's about preventing the steel reinforcement and concrete from coming into contact in the middle area of the beam, but I don't know what to do.
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STKO Team
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Re: Non-bonded segment

Post by STKO Team » Tue Jan 27, 2026 9:02 am

In a beam model with fiber sections, the perfect bond between steel and concrete is assumed (plane sections remain plain).

If you want to use beam model then you should do something like this:
https://opensees.berkeley.edu/workshop/ ... ration.pdf

junruli
Posts: 9
Joined: Thu Jan 15, 2026 1:10 am

Re: Non-bonded segment

Post by junruli » Tue Jan 27, 2026 12:40 pm

STKO Team wrote:
Tue Jan 27, 2026 9:02 am
In a beam model with fiber sections, the perfect bond between steel and concrete is assumed (plane sections remain plain).

If you want to use beam model then you should do something like this:
https://opensees.berkeley.edu/workshop/ ... ration.pdf
I don't quite understand what you mean. What I mean is that steel bars in the circled area of the diagram are equipped with sleeve-like items to prevent contact with the concrete. Currently, I want to implement this idea in STKO, but I don't know how to proceed.
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kesavapraba
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Re: Non-bonded segment

Post by kesavapraba » Wed Feb 11, 2026 9:44 am

Hi, You might do the followings:
1] Model the concrete part using solid (ASDConcrete3D)
2] bonded rebars as embedded dispBeamColumn element with slip (ASDEmbeddedRebarWithSlip) interface between concrete and rebar,
3] the unbonded steel rebars as displBeamColumn element but without any embedment or interface between concrete
:: With best wishes ::
Prabakaran Kesavan

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