rc and rt in uniaxialMaterial ConcreteCM

[dgale]

Hello everybody,
I want to use uniaxialMaterial ConcreteCM but I don't know how to obtain parameters rc and rt. The manual says that is inside of this paper:

Tsai W.T. (1988). Uniaxial compressional stress-strain relation of concrete, ASCE, J. Struct. Eng., 114(9): 2133–2136.

But in this paper I just find parameters n and m. Any of them match with values in the example. In the example they've got rc=7 with fc'=6.2ksi. How did they do? I need a practical example or the equations which define rc and rt.

Thank you very much.

David

[selimgunay]

Could you please send an email to the first author in the wiki page and please let me know if you don't get a response.

[dgale]

Thanks for your advise!
I'll tell you if I don't get response.

[dgale]

The author answer for everyone that has the same doubt is below.

"I usually calibrate these parameters to match the tested concrete strain stress curve. If I dont have the test results, then I try to match them with some of the commonly used models (e.g., Saatcioglu and Razvi, Chang and Mander, etc.). I never used the expressions, although I think there might be some available in the literature. Also, take a look at the Chang and Mander reference provided in the Wiki page, you might find something there. Finally, I explained how I did this originally in my PhD dissertation from UCLA"

As conclusion, I think the parameter rc and rt are the parameter n in the paper, but he never used.

[EricsonEncinaZ]

In Kolozvari's PhD thesis (http://escholarship.org/uc/item/6sm78634) in page 91 he defined the Shape Parameter in equation 3-75, you may have a look.

[farazmizani]

hello everyone,
I use concreteCM command in my model and I have the same problem which is finding exact value for shape parameter, I read all the references( I mean 6 references that are in wiki page ) and all of them suggested using chand and mander 1994 eq (3-46c) which is r=f'c/750-1.9 (psi) , but the value of example does not match neither with chang and mander, and tsai, and what is shape parameter equation for tensile part? because we can't use this one for stresses less than 2000psi.
also we can't use it for confined part of model based on some articles the shape parameter equation must be nonlinear equation.
please let me know how could you solve this.