hysteretic behavior

[mari0316]

Hi Dear All,

I have modeled hysteretic behavior of a material combining ReinforcingSteel and Elastic, but the behavior is weird.
I cannot check behavior of strain hardening(from esh to eult) after yield plateau.
How can I solve it?

I am giving the build model file below for your kind observation.
Also, basic units are kN, m.

Thank you,
K.H.
--------------------------------------------------------------------------------------
source LibUnits.tcl

model basic -ndm 2 -ndf 2

node 1 0.0 0.0
node 2 0.0 0.0

fix 1 1 1 0
fix 2 0 1 0

#####################
uniaxialMaterial Elastic 1 1000.
#
set Fy2 [expr 396*$MPa];
set Fu2 [expr 532*$MPa];
set Es2 [expr 200*$GPa];
set Esh2 [expr 3*$GPa]
set esh2 0.007
set eult2 0.15
uniaxialMaterial ReinforcingSteel 2 $Fy2 $Fu2 $Es2 $Esh2 $esh2 $eult2

#uniaxialMaterial Parallel 3 1 2
#####################

element zeroLength 1 1 2 -mat 3 -dir 1

recorder Node -file Reac1.out -load -nodes 1 -dof 1 reaction
recorder Node -file Disp1.out -load -nodes 2 -dof 1 disp

pattern Plain 1 Linear {
load 2 1.0 0.0
}

system BandSPD
constraints Transformation
numberer RCM
test EnergyIncr 1.e-5 6 0;
algorithm NewtonLineSearch 0.8

###### Sinusoidal Displacement #####
set IDctrlNode 2;
set IDctrlDOF 1;
set NoStep 1000;
set maxD 0.02;
set NStep 0.;
set pi 3.14159;

while {$NStep < $NoStep} {
set NStep [expr $NStep+1.];
set DStep [expr $NStep/100.0*($maxD*sin(2.0*$pi*$NStep/$NoStep*4.0)-$maxD*sin(2.0*$pi*($NStep-1)/$NoStep*4.0))];

integrator DisplacementControl $IDctrlNode $IDctrlDOF $DStep
analysis Static

analyze 1
}
----------------------------------------------------------------------------------------

[selimgunay]

I would recommend to check your model with the elastic material first, then the ReinforcingSteel and after making sure both work as expected, you can proceed to the parallel material. Since you have only two dof, you should change

fix 1 1 1 0
fix 2 0 1 0

to

fix 1 1 1
fix 2 0 1

[mari0316]

Thank you for your kind reply.

However, I can't still solve the issue I mentioned above.
Could you recommend other idea to solve it?

Thanks again,

[selimgunay]

How do the results look with the elastic material only and the ReinforcingSteel only? Are they as expected?

[mari0316]

The result of the RinforcingSteel is not expected.
So, I decide to use other material model!

Thank you,

[selimgunay]

You can use Steel02.