Update material parameters during loading

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aminrahmani
Posts: 25
Joined: Tue Nov 11, 2008 4:43 am
Location: University of British Columbia
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Update material parameters during loading

Post by aminrahmani »

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.
Amin Rahmani
kyonten
Posts: 29
Joined: Thu Jan 29, 2009 7:11 pm
Location: George Washington University

updateParameter

Post by kyonten »

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
Posts: 25
Joined: Tue Nov 11, 2008 4:43 am
Location: University of British Columbia
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Update material parameters during loading

Post by aminrahmani »

Hi,

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

Thanks!
Amin Rahmani
kyonten
Posts: 29
Joined: Thu Jan 29, 2009 7:11 pm
Location: George Washington University

Post by kyonten »

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
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Location: University of British Columbia
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Update material parameters during loading

Post by aminrahmani »

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.
Amin Rahmani
kyonten
Posts: 29
Joined: Thu Jan 29, 2009 7:11 pm
Location: George Washington University

Post by kyonten »

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
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Joined: Fri Apr 03, 2009 2:28 am
Location: wuhan

Post by youyicun2008 »

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

:cry:
Maybe some can solve it as soon as possible.

Thanks in advance. :twisted:
aminrahmani
Posts: 25
Joined: Tue Nov 11, 2008 4:43 am
Location: University of British Columbia
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Post by aminrahmani »

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.
Amin Rahmani
mcganncr
Posts: 12
Joined: Tue May 27, 2008 4:22 pm
Location: University of Canterbury

Post by mcganncr »

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
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Joined: Sat Sep 10, 2011 12:06 pm
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Re: Update material parameters during loading

Post by markove »

I was also having problem with this ...now I got it..hopefully I will be able to solve it now
health is wealth
kidgifts12
Posts: 3
Joined: Tue Feb 21, 2012 12:47 am

Re: Update material parameters during loading

Post by kidgifts12 »

wow i have successfully completed this!!! :D :)
Emakader
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Joined: Mon Mar 12, 2012 12:59 am

Re: Update material parameters during loading

Post by Emakader »

Soil modeling in the important part of any structure.
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Fadan62
Posts: 1
Joined: Sun Mar 18, 2012 10:25 am

Re: Update material parameters during loading

Post by Fadan62 »

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