Concrete 07 Confussions

[taneryilmaz]

Hi,

For my research project, I'm doing inelastic response history analyses of 3-D bridge structures. I'm using displacement-based fiber elements for the concrete bent columns. For the material definitions of unconfined and unconfined concrete, I'm in between using Concrete02 and Concrete07. I consider the Mander et al. (1988) material model for confined concrete. I'd be happy if you have a look at my questions below:

1- For the definition of Concrete07, which modulus of elasticity should be considered for confined concrete ? The one calculated according to the strength of unconfined concrete or confined concrete. Concrete07 already gives a bit of stiffer response as compared to Concrete02 when I use the same modulus for both confined and unconfined concrete.

2- For the same model, my analysis takes nearly 20 minutes if I use Concrete07, while it takes nearly 2 hours if I use Concrete02. The outcoming response values are not so off to each other. Is there anyone who experienced such kind of effect in using Concrete07.

I also want to note that the links in the page (http://opensees.berkeley.edu/wiki/index ... rete_Model) are all dead, and the link (http://opensees.berkeley.edu/OpenSees/m ... l/4055.htm) is the only source to reach how to use this material.

Thank you in advance.

Taner.

[vesna]

1. If you look at the Mander's paper from 1988 where he tested confined and unconfined concrete you will see that the Ec initial for the two types of concrete are the same.

2. I did not experience that before.

Thanks for letting us know about dead links. For now I provided a link to the old page.

[taneryilmaz]

Thank you Vesna,

1. I have that paper, I think I've missed that. Thanks again for your notification.

2. I also found it a bit strange. My first prediction for that behavior is; in Concrete07, the crushing strain is not explicitly defined, allowing very large strains with the term xn.

For the old link, there is an error in calculation of the strain at max. unconfined concerete strength (SI unit is wrong).

Taner.

[vesna]

Taner,

Would you write the correct formula for strain at max. unconfined concerete strength in SI units.

Thanks,
Vesna

[wuhaoshrek]

vesna wrote:
> Taner,
>
> Would you write the correct formula for strain at max. unconfined concerete
> strength in SI units.
>
> Thanks,
> Vesna

peak strain of unconfined concrete in Concrete01 model should be like this:

epsc0=fco'^(0.25)/1152.7 (SI units:)

The equations showed in the old link is in picture, hope somebody else could revise it.

I have checked the equation in the original Mander's report, it is the same as shown on
the website. So I guess the authors may make a mistake in their report.

[ftoledoj]

taneryilmaz wrote:
> Hi,
>
> For my research project, I'm doing inelastic response history analyses of
> 3-D bridge structures. I'm using displacement-based fiber elements for the
> concrete bent columns. For the material definitions of unconfined and
> unconfined concrete, I'm in between using Concrete02 and Concrete07. I
> consider the Mander et al. (1988) material model for confined concrete. I'd
> be happy if you have a look at my questions below:
>
> 1- For the definition of Concrete07, which modulus of elasticity should be
> considered for confined concrete ? The one calculated according to the
> strength of unconfined concrete or confined concrete. Concrete07 already
> gives a bit of stiffer response as compared to Concrete02 when I use the
> same modulus for both confined and unconfined concrete.
>
> 2- For the same model, my analysis takes nearly 20 minutes if I use
> Concrete07, while it takes nearly 2 hours if I use Concrete02. The
> outcoming response values are not so off to each other. Is there anyone who
> experienced such kind of effect in using Concrete07.
>
> I also want to note that the links in the page
> (http://opensees.berkeley.edu/wiki/index ... rete_Model)
> are all dead, and the link
> (http://opensees.berkeley.edu/OpenSees/m ... l/4055.htm) is the
> only source to reach how to use this material.
>
> Thank you in advance.
>
> Taner.

Hi taner am trying to model the same material, by any chance you can send me the opensees script to see how you described it?

mi email: felipe.toledo.j@gmail.com

thanks in advance