About FRPConfinedConcrete

[shiRo]

Dear STKO team,
I am trying to use FRPConfinedConcrete Material, I have filled in all the information about it, but when I run the analysis I am prompted with an error in the material model, the error message is as shown in the figure, so the reason for the error is whether it is due to incomplete data input, but in the STKO can only enter this, can you give me some advice, thank you very much!
Best wishes

[kesavapraba]

Hi, I can see only 16 out of 18 parameters of FRPConfinedConcrete material definitions are shown in STKO widget. Two parameters "fyl" and "useBuck" are missing. This issue will be communicated to STKO Team.
Now, as a quick fix, I would suggest you to manually edit the FRPConfinedConcrete material in material.tcl file with 18 parameters once the TCL files are generated from STKO. Then, you can double click the RunSolver.bat in the same folder where you have the SCD file.

[shiRo]

Hi, I can see only 16 out of 18 parameters of FRPConfinedConcrete material definitions are shown in STKO widget. Two parameters "fyl" and "useBuck" are missing. This issue will be communicated to STKO Team.
Now, as a quick fix, I would suggest you to manually edit the FRPConfinedConcrete material in material.tcl file with 18 parameters once the TCL files are generated from STKO. Then, you can double click the RunSolver.bat in the same folder where you have the SCD file.

Okay thanks a lot!
Also I have a question, if the material I am using is not FRP but UHPC, is it equally applicable to this calculation model to work out the properties of the confined concrete?

[kesavapraba]

Yes, the material model that you used is a uniaxial one, which is a general model and can be used to simulate any other identical material. However, you should check if the required features of UHPC are properly represented by the uniaxial model. Otherwise, you can try "Concrete02" with/without confinement properties.

[shiRo]

Yes, the material model that you used is a uniaxial one, which is a general model and can be used to simulate any other identical material. However, you should check if the required features of UHPC are properly represented by the uniaxial model. Otherwise, you can try "Concrete02" with/without confinement properties.

Okay I get it. Thanks a lot.

[shiRo]

Yes, the material model that you used is a uniaxial one, which is a general model and can be used to simulate any other identical material. However, you should check if the required features of UHPC are properly represented by the uniaxial model. Otherwise, you can try "Concrete02" with/without confinement properties.

Hello, I've encountered a new problem when using FRPconfinedconcrete in the past few days, during the analysis process, "RuptureFRP" appears and the analysis process stops. (The values of $fyh and $useBuck are 400 and 0). In the description of this material it is mentioned that the analysis is not terminated by sheath rupture, but I don't see any change in the monitor anymore. Even if I make some changes in Analysiscommand, it never finishes the analysis. Attached is my model file, I hope you can help me.Thanks!

[kesavapraba]

Hi, I can see $fyh value in your script is set to 28.0 but not 400. This may not be the issue but anyway check the properties again. Please note that the source code throws error when the following condition is met:
et_cover >= k*eju

where, et_cover is the hoop strain of the FRP material
and k and eju are defined in the material's documention page.

Also, the documention says the stress-strain response is terminated when the hoop strain exceeds the FRP strain, as found in the following sentences:

Finally, the stress-strain response of FRP-confined concrete is terminated by jacket rupture owing to hoop strains exceeding the strain capacity of the material or to interaction of the jacket with the buckled longitudinal bars.

You can write to the author of the material for better understanding about the usage of the material.

Link for the material documentation:
https://opensees.berkeley.edu/wiki/inde ... edConcrete