About openses uniaxial material stress-strain curve
Moderators: silvia, selimgunay, Moderators
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- Posts: 5
- Joined: Sat Jun 08, 2019 3:32 am
- Location: Beijing University of Civil Engineering and Architecture
About openses uniaxial material stress-strain curve
Hello engineers,
I want to extract the stress-strain curve of opensees uniaxialmaterial.I designed a prismatic test block to simulate.
Below is the code:
wipe
model BasicBuilder -ndm 2 -ndf 3
node 1 0.0 0.0
node 2 0.0 0.3
fix 1 1 1 1
uniaxialMaterial Concrete01 1 -36800 -0.002 -6000 -0.008
section Fiber 1 {
patch rect 1 10 10 -0.075 -0.075 0.075 0.075
}
geomTransf Linear 1
element nonlinearBeamColumn 1 1 2 5 1 1
recorder Node -file C2.out -time -node 2 -dof 1 2 3 disp
pattern Plain 1 Linear {
load 2 0 -1 0
}
constraints Plain
numberer Plain
system BandGeneral
test NormDispIncr 1.0e-6 100 2
algorithm Newton
integrator DisplacementControl 2 2 0.000001
analysis Static
analyze 1000
I get the following error :
ForceBeamColumn2d::update() -- could not invert flexibility
Is the method I used wrong?
Can anyone help me by that error ??
I appreciate your help.
I want to extract the stress-strain curve of opensees uniaxialmaterial.I designed a prismatic test block to simulate.
Below is the code:
wipe
model BasicBuilder -ndm 2 -ndf 3
node 1 0.0 0.0
node 2 0.0 0.3
fix 1 1 1 1
uniaxialMaterial Concrete01 1 -36800 -0.002 -6000 -0.008
section Fiber 1 {
patch rect 1 10 10 -0.075 -0.075 0.075 0.075
}
geomTransf Linear 1
element nonlinearBeamColumn 1 1 2 5 1 1
recorder Node -file C2.out -time -node 2 -dof 1 2 3 disp
pattern Plain 1 Linear {
load 2 0 -1 0
}
constraints Plain
numberer Plain
system BandGeneral
test NormDispIncr 1.0e-6 100 2
algorithm Newton
integrator DisplacementControl 2 2 0.000001
analysis Static
analyze 1000
I get the following error :
ForceBeamColumn2d::update() -- could not invert flexibility
Is the method I used wrong?
Can anyone help me by that error ??
I appreciate your help.
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- Posts: 913
- Joined: Mon Sep 09, 2013 8:50 pm
- Location: University of California, Berkeley
Re: About openses uniaxial material stress-strain curve
uniaxialMaterial Concrete01 1 -36800 -0.002 -6000 -0.008
Can you first replace this with an elastic material to see if the problem is due to this?
Can you first replace this with an elastic material to see if the problem is due to this?
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- Posts: 5
- Joined: Sat Jun 08, 2019 3:32 am
- Location: Beijing University of Civil Engineering and Architecture
Re: About openses uniaxial material stress-strain curve
Thank you so much for your help!The program runs successfully after replacing concrete01 with elastic materials.But I want to get the stress-strain curve of other uniaxial materials. Is there a problem with the element I selected?Or my whole method is wrong?selimgunay wrote: ↑Mon Oct 05, 2020 12:21 amuniaxialMaterial Concrete01 1 -36800 -0.002 -6000 -0.008
Can you first replace this with an elastic material to see if the problem is due to this?
Re: About openses uniaxial material stress-strain curve
You are putting the beam into flexure and there is no r/f steel so no tension force to balance compression force.
If all you want is stress-strain from a material, use a truss element, not a beam-column element.
If all you want is stress-strain from a material, use a truss element, not a beam-column element.
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- Posts: 913
- Joined: Mon Sep 09, 2013 8:50 pm
- Location: University of California, Berkeley
Re: About openses uniaxial material stress-strain curve
Another option is to apply axial shortening to your column.
This OpenSees based application allows visualizing stress-strain relations of common steel and concrete materials used in OpenSees
https://apps.peer.berkeley.edu/bridgepbee/
This OpenSees based application allows visualizing stress-strain relations of common steel and concrete materials used in OpenSees
https://apps.peer.berkeley.edu/bridgepbee/
Re: About openses uniaxial material stress-strain curve
you could try another modelbuilder provided just for testing material .. here is an example i used awhile back
model UniaxialMaterialTest
uniaxialMaterial Elastic 1 3000
uniaxialMaterial MinMax 2 1 -min -0.001
uniaxialMaterial MinMax 3 1 -max 0.001
uniaxialMaterial MinMax 4 1 -min -0.001 -max 0.001
set strains {0.00 0.0005 0.001 0.002 0.001 0.0005 0.0 -0.0005 -0.0001
-0.002 0.0}
proc doStrains {matTag strains} {
puts "\n Testing $matTag"
uniaxialTest $matTag
foreach strain $strains {
strainUniaxialTest $strain
set stress [stressUniaxialTest]
set tangent [tangUniaxialTest]
puts "strain: $strain stress: $stress tangent: $tangent"
}
}
doStrains 2 $strains
doStrains 3 $strains
doStrains 4 $strains
model UniaxialMaterialTest
uniaxialMaterial Elastic 1 3000
uniaxialMaterial MinMax 2 1 -min -0.001
uniaxialMaterial MinMax 3 1 -max 0.001
uniaxialMaterial MinMax 4 1 -min -0.001 -max 0.001
set strains {0.00 0.0005 0.001 0.002 0.001 0.0005 0.0 -0.0005 -0.0001
-0.002 0.0}
proc doStrains {matTag strains} {
puts "\n Testing $matTag"
uniaxialTest $matTag
foreach strain $strains {
strainUniaxialTest $strain
set stress [stressUniaxialTest]
set tangent [tangUniaxialTest]
puts "strain: $strain stress: $stress tangent: $tangent"
}
}
doStrains 2 $strains
doStrains 3 $strains
doStrains 4 $strains
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- Posts: 5
- Joined: Sat Jun 08, 2019 3:32 am
- Location: Beijing University of Civil Engineering and Architecture
Re: About openses uniaxial material stress-strain curve
Thanks professor,I tried to use the truss element, but the program still fails.Then, I solved the problem by using zeroLength element and changing the dimensions.Thanks for your help!
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- Posts: 5
- Joined: Sat Jun 08, 2019 3:32 am
- Location: Beijing University of Civil Engineering and Architecture
Re: About openses uniaxial material stress-strain curve
I solved the problem by using zeroLength element and changing the dimensions.Thanks for your help!selimgunay wrote: ↑Mon Oct 05, 2020 11:59 amAnother option is to apply axial shortening to your column.
This OpenSees based application allows visualizing stress-strain relations of common steel and concrete materials used in OpenSees
https://apps.peer.berkeley.edu/bridgepbee/
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- Posts: 5
- Joined: Sat Jun 08, 2019 3:32 am
- Location: Beijing University of Civil Engineering and Architecture
Re: About openses uniaxial material stress-strain curve
My problem has been solved, but still thank you for the new solution, I will try to solve it with your method.Thanks a lot!fmk wrote: ↑Mon Oct 05, 2020 7:47 pmyou could try another modelbuilder provided just for testing material .. here is an example i used awhile back
model UniaxialMaterialTest
uniaxialMaterial Elastic 1 3000
uniaxialMaterial MinMax 2 1 -min -0.001
uniaxialMaterial MinMax 3 1 -max 0.001
uniaxialMaterial MinMax 4 1 -min -0.001 -max 0.001