Thermal analysis and Strain restriction

[fh]

Hi

I want to perform thermal analysis of steel structures but can not restrict strain of material by using Steel01Thermal and Fatigue material or Max Min material.Therefore it is not possible to detect structural element failure while conducting such analysis. So It's highly appreciated if you can help me how to be sure that the material doesn't go beyond its capacity.

Thanks

[fmk]

why can't you use the MinMax mateial http://opensees.berkeley.edu/wiki/index ... x_Material. Other that this the option option is to write some code or use the eleResponse command to monitorr your strains and do something if they get too big.

[fh]

fmk wrote:
> why can't you use the MinMax mateial
> http://opensees.berkeley.edu/wiki/index ... x_Material. Other that
> this the option option is to write some code or use the eleResponse command
> to monitorr your strains and do something if they get too big.

Dear Frank

Thanks for your reply but when I use MinMax material or Fatigue material together with Steel01Thermal or even Steel02Thermal I get the following error and then analysis fails:

Steel01Thermal::setTrialStrain(double strain, strainRate) - should never be called

Actually I want to eliminate those fibers which go beyond their capacity, for example exceed the ultimate strain in order that I can monitor the loss of stiffness in my model. In my current model it continues analysis till numerical instability occurs even when some structural elements undergo high temperature.

Thanks

[fmk]

i have made a change to the MinMax material to fix that error. it will be in any release >= 5597 of the code.

[fh]

fmk wrote:
> i have made a change to the MinMax material to fix that error. it will be in any
> release >= 5597 of the code.

Dear Frank

I use the latest version of OpenSees (2.4.2 Rev 5540) but I have the same problem. When do you think it will be released?
For another thing when I want to record stress and strain of any fiber in fiberThermal sections I get empty file. How can I fix it?

Thanks

[brag006]

You need to download the source code to get the latest revision (5597) or until fmk updates the exe file available on the website.

[fh]

Hi

I tried the new version (2.4.3 rev 5621) and although I didn't get the previous error I got the new one and analysis failed.

WARNING BandGenLinLapackSolver::solve() -LAPACK routine returned 28
WARNING NewtonRaphson::solveCurrentStep() - the LinearSysOfEqn failed in solve()
DirectIntegrationAnalysis::analyze() - the Algorithm failed at time 0.01

So what do you suggest to do?

Thanks

[brag006]

Check your model. Make sure all the nodes are correct and you've provided enough constraints. If you can't fix it post the code.

[fh]

I have checked everything. when I use just the following material definition it works

uniaxialMaterial Steel02Thermal 1 2.75e8 2.1e11 0.01;

But when I change it to this:

uniaxialMaterial Steel02Thermal 2 2.75e8 2.1e11 0.01;
uniaxialMaterial MinMax 1 2 -min -0.01864 -max 0.01864

it gives the error I said

WARNING BandGenLinLapackSolver::solve() -LAPACK routine returned 28
WARNING NewtonRaphson::solveCurrentStep() - the LinearSysOfEqn failed in solve()
DirectIntegrationAnalysis::analyze() - the Algorithm failed at time 0.01

it has made me really confused.

[brag006]

Post your code

[fh]

Hi brag006

wipe;
model BasicBuilder -ndm 2 -ndf 3;
set dataDir Data;
file mkdir $dataDir;


proc Wsection { secID matID d bf tf tw nfdw nftw nfbf nftf} {
set dw [expr $d - 2 * $tf]
set y1 [expr -$d/2]
set y2 [expr -$dw/2]
set y3 [expr $dw/2]
set y4 [expr $d/2]

set z1 [expr -$bf/2]
set z2 [expr -$tw/2]
set z3 [expr $tw/2]
set z4 [expr $bf/2]

section fiberSecThermal $secID {
# nfIJ nfJK yI zI yJ zJ yK zK yL zL
patch quadr $matID $nfbf $nftf $y1 $z4 $y1 $z1 $y2 $z1 $y2 $z4
patch quadr $matID $nftw $nfdw $y2 $z3 $y2 $z2 $y3 $z2 $y3 $z3
patch quadr $matID $nfbf $nftf $y3 $z4 $y3 $z1 $y4 $z1 $y4 $z4
}
}


set X0 0.0;
set X1 6.0;
set Y0 0.0;
set Y1 3.6;

node 1 $X0 $Y0
node 2 $X0 $Y1
node 3 $X1 $Y0
node 4 $X1 $Y1

fix 1 1 1 1
fix 3 1 1 1


uniaxialMaterial Steel02Thermal 2 2.75e8 2.1e11 0.01;
uniaxialMaterial MinMax 1 2 -min -0.01864 -max 0.01864

Wsection 1 1 0.3620 0.3705 0.0207 0.0123 5 5 5 5

geomTransf Corotational 1 ;

set np1 5;

element dispBeamColumnThermal 1 1 2 $np1 1 1
element dispBeamColumnThermal 2 3 4 $np1 1 1
element dispBeamColumnThermal 3 2 4 $np1 1 1

mass 2 15300 15300 0
mass 4 15300 15300 0




pattern Plain 1 "Path Series -time {0 5 1000} -values {0 1 1} -factor 1" {
eleLoad -ele 3 -type -beamUniform -36000;
}

set Path1 "Series -time {0 7 1000} -values {0 0 1}"

pattern Fire 2 $Path1 $Path1 $Path1 $Path1 $Path1 $Path1 $Path1 $Path1 $Path1 {
set T 1000;
set L 0.1905
eleLoad -ele 1 -type -beamThermal $T -$L $T $L;
eleLoad -ele 2 -type -beamThermal $T -$L $T $L;
eleLoad -ele 3 -type -beamThermal $T -$L $T $L;
}


recorder display DispShape 10 10 700 700 -wipe
vrp 15 7.2 0
vup 0 1 0
vpn 0 0 1
prp 0 0 100
viewWindow -18 18 -20 20
plane 0 150
projection 0
port -1 1 -1 1
fill 1
display 1 0 3


equalDOF 2 4 1

recorder Element -file $dataDir/eleinfglobal1.out -time -ele 1 2 3 globalForce;
recorder Node -file $dataDir/nodesD1.out -time -node 2 4 -dof 1 2 3 disp;

test EnergyIncr 1.0e-6 100
algorithm Newton
numberer RCM
constraints Transformation
system BandGeneral
integrator TRBDF3
analysis VariableTransient


analyze 10000 0.1;

[fh]

Hi Frank,

Would you please help me with this issue?

Regards,

[fmk]

you must use one of the thermal materials with the thermal sections .. they don't just set stress and strain, they material needs to do other stuff. because the MinMax is not doing it, the ThermalSection in it's iterations is coming up with a strain of NAN when the thermal load is applied, to which the tangent returned is NAN and hence the solver is failing.

[fh]

Thanks Frank but what do you reckon for solving this issue and restricting strain during thermal action?