Concrete 07 - Chang & Mander 1994

[gomezhuci]

Hello all,

While I was studying about the uniaxial material "Concrete 07" I found the Chang and Mander NCEER report in 1994.

Looking at the expressions they recommend for a complete stress-strain curve for unconfined concrete I found the following:

epsilon'c = f'c ^ (1/4) / 4000 (psi)

epsilon'c = f'c ^ (1/4) / 28 (MPa)

So, if we plug in a value of f'c = 4000psi = 27.6MPa it results in the following values:

epsilon'c = 0.001988177 (using psi) and epsilon'c = 0.081843656 (using MPa)

Since epsilon'c is a dimensionless parameter. Is not supposed to be the same value regardless of the f'c units?

So, I found that the expression in SI units for epsilon'c should be approximately:

epsilon'c = f'c ^ (1/4) / 1150 (MPa)

PLEASE SOMEBODY CONFIRM THIS!! I COULD SEND YOU A COPY OF THE REPORT BY REQUEST. THANK YOU VERY MUCH!

[vesna]

There is obviously a typo in that document. Your proposed formula looks good to me.

[gomezhuci]

Thanks vesna,

Yes. So there is the same typo in the OpenSees Command Manual in the explanation of the Concrete 07 uniaxial material.
Although the version I looked in is the one from may 2009.

[vesna]

I looked at the Concrete07 page (http://opensees.berkeley.edu/wiki/index ... rete_Model) and could not find the expressions you were commenting on.

[diqingshuang]

Hi vesna

it is here listing all the equations for different parameters

http://opensees.berkeley.edu/OpenSees/m ... l/4055.htm


vesna wrote:
> I looked at the Concrete07 page
> (http://opensees.berkeley.edu/wiki/index ... rete_Model)
> and could not find the expressions you were commenting on.

[vesna]

That is the old manual.

Look at this one:
http://opensees.berkeley.edu/wiki/index ... rete_Model

[wuhaoshrek]

gomezhuci wrote:
> Hello all,
>
> While I was studying about the uniaxial material "Concrete 07" I
> found the Chang and Mander NCEER report in 1994.
>
> Looking at the expressions they recommend for a complete stress-strain
> curve for unconfined concrete I found the following:
>
> epsilon'c = f'c ^ (1/4) / 4000 (psi)
>
> epsilon'c = f'c ^ (1/4) / 28 (MPa)
>
> So, if we plug in a value of f'c = 4000psi = 27.6MPa it results in the
> following values:
>
> epsilon'c = 0.001988177 (using psi) and epsilon'c = 0.081843656 (using MPa)
>
> Since epsilon'c is a dimensionless parameter. Is not supposed to be the
> same value regardless of the f'c units?
>
> So, I found that the expression in SI units for epsilon'c should be
> approximately:
>
> epsilon'c = f'c ^ (1/4) / 1150 (MPa)
>
> PLEASE SOMEBODY CONFIRM THIS!! I COULD SEND YOU A COPY OF THE REPORT BY
> REQUEST. THANK YOU VERY MUCH!

YOU ARE RIGHT!

[ftoledoj]

In this page of the manual listed here is not possible to see the images , says that are restricted.

http://opensees.berkeley.edu/wiki/index ... rete_Model