Update material parameters during loading

aminrahmani · Post by **aminrahmani** » Mon Apr 27, 2009 9:42 am

Hi everybody,

I am using the EightNode_Brick_u_p elements in my model. The permeability coefficient should be changed during earthquake loading. Is there any command to update the permeability coefficient during earthquake excitation?

Thanks in advance.

kyonten · Post by **kyonten** » Thu Apr 30, 2009 5:46 pm

If you are using the PressureDependMultiYield or PressureIndependMultiYield models, you can use the updateParameter command to update the permeability. See the soil material/element part of the opensees manual.

aminrahmani · Post by **aminrahmani** » Thu Apr 30, 2009 10:49 pm

Hi,

I am using Dafalias-Manzari model so it seems that I can't update permeability during earthquake excitation. Am I right?

Thanks!

kyonten · Post by **kyonten** » Mon May 04, 2009 11:34 am

I haven't dealt much with the template elastic-plastic material models in opensees. If these material models can be used with the solid-fluid coupled elements in opensees (i.e. usage of these elements is not restricted to only the UCSD soil models), I think you can use the command 'updateParameter' to assign new value for the permeability parameters. Simply use the command (see the opensees manual):

updateParameter -element $tag -hPerm $newVal

hPerm is the horizontal permeability. You can do the same for the vertical permeability.

You wouldn't know if that will work until you try it so give it a go and let us know.

Good luck!

aminrahmani · Post by **aminrahmani** » Tue May 05, 2009 3:04 am

Hi kyonten,

Thanks for your help. I used the command, updateParameter - element 1 -hPerm 6.6e-5, which is in the manual but I got the following message both for the elastic-plastic material and for the UCSD soil models:

Expected integer but got “- element”
Studying the examples in the cyclic.ucsd.edu/opensees , I saw the following command to update the reference low-strain shear modulus. The command completely differs from that in the manual :

updateMaterials -material 2 bulkModulus [expr $G*2/3.]

Using the command in the manual to update shear modulus, I got the same massage (i.e. Expected integer but got “- material”). Do you have any comment about this?
I am using the new version of OpenSees(ver. 2.1.0).

Many thanks.

kyonten · Post by **kyonten** » Fri May 08, 2009 2:44 pm

Looks like other users had the same problem with these commands in the earlier version of opensees. I don't know if the problem is fixed yet in the recent version. May be these commands are no longer used.

youyicun2008 · Post by **youyicun2008** » Mon May 11, 2009 6:46 am

I have a same problem of this "Expected integer but got “- element” ".

Maybe some can solve it as soon as possible.

Thanks in advance.

aminrahmani · Post by **aminrahmani** » Mon May 11, 2009 11:49 am

Hello

Read this:

cyclic.ucsd.edu/opensees/OSManual_UCSD_soil_models_2008.pdf

I used the commands in this paper, but I got another error. If you can get correct results, please tell me.

mcganncr · Post by **mcganncr** » Tue Oct 19, 2010 11:38 am

Using the advice that was posted here and some of my own experience cracking these little OpenSees problems that seem arise, I think that I have figured this one out.

The syntax given in the manual at cyclic.ucsd.edu/opensees/OSManual_UCSD_soil_models_2008.pdf seems to be the way to go.

Example usage for updating the permeabilities for 2 elements.

# set parameter tags
parameter 100001 element 1 hPerm
parameter 100002 element 1 vPerm
parameter 100003 element 2 hPerm
parameter 100004 element 2 vPerm

# update permeabilities
updateParameter 100001 1.0e-5
updateParameter 100002 1.0e-5
updateParameter 100003 1.0e-6
updateParameter 100004 1.0e-6

If you get an error about a parameter tag already being in the domain, try changing the tag ID numbers until it works. In my analysis I just added 10000 to the front of my sequential parameter IDs so these tags were much larger numbers than the tags I used elsewhere in my analysis.

Hope this helps,

Chris McGann
University of Washington

markove · Post by **markove** » Sat Sep 10, 2011 12:12 pm

I was also having problem with this ...now I got it..hopefully I will be able to solve it now

kidgifts12 · Post by **kidgifts12** » Tue Feb 21, 2012 12:58 am

wow i have successfully completed this!!!

Emakader · Post by **Emakader** » Mon Mar 12, 2012 1:09 am

Soil modeling in the important part of any structure.
<a href="http://trivalleyrecyclers.com/">Tri Valley Recyclers</a>

Fadan62 · Post by **Fadan62** » Sun Mar 18, 2012 10:31 am

Soil molding is the most important to produce different type of pattern and product. Material must be update before loading to obtain good output.

The OpenSees Community