thermals loads

[chen]

Hi
I am trying to uses OP to solves portal frames where the loads are linear loads and thermal loads.
How can I define thermals loads in OP or is there an optional way to do it?

[Boris]

You can allways find the strains resulting from thermal load, then find stress through constitutive equations and finally integrate stresses to get nodal load for beams. I even think that this can be found in some books (together with equivalent nodal loads for different distributed loads...).

I've got couple on my shelfs, but doubt that you will be able to find them in your library...

It should be trivial for symmetric beams and uniform temperature increase...

Boris

[chen]

Hi Boris, thanks
I Have alrady done but I am not sure about the results.
Do you think that entering thermal loads like loads in the extremity of the beam the forces in the extremity of the beam will be correct?

Even if I enter the thermal loads like NODAL LOADS the results are diferent that entering them like LOADS IN THE EXTREMITY OF THE BEAM. Which is the correct way to have a well modelisation and corrects results ?
Here i send you the files.They are the same but one with 3dof and the other with 6dof. Thanks

The stress value 39756.0882 I have obtained like :
Stress =temperature variation * coef. dilat. termic * section * Elast. Modul


3dof PORTALFRAME nodal loads

wipe
model basic -ndm 3 -ndf 6
set L1 5000
set L2 5000
node 1 0 0 0
node 2 0 $L1 0
node 3 $L2 $L1 0
fix 1 1 1 1 1 1 1
fix 3 1 1 1 1 1 1

set E 7100.478
set A 5956.4596
set J 148697059
set Iz 74375333.68
set Iy 74375333.68
set G 4615.3107
set v 0.3

geomTransf Linear 1 0 0 1

element elasticBeamColumn 1 1 2 $A $E $G $J $Iy $Iz 1
element elasticBeamColumn 2 2 3 $A $E $G $J $Iy $Iz 1

set Px1 -39756.0882
set Px2 39756.0882
set Py 0
set Pz 0
set xL1 0
set xL2 1

pattern Plain 1 Linear {
eleLoad -ele 1 2 -type -beamPoint $Py $Pz $xL1 $Px1
eleLoad -ele 1 2 -type -beamPoint $Py $Pz $xL2 $Px2
}
constraints Transformation
numberer RCM
algorithm Linear
integrator LoadControl 1
analysis Static

recorder Element -file forces.out -time -ele all force
analyze 1
print


6dof PORTALFRAME loads in beam

wipe
model basic -ndm 2 -ndf 3

set L1 5000
set L2 5000

node 1 0 0
node 2 0 $L1
node 3 $L2 $L1

fix 1 1 1 1
fix 3 1 1 1

set E 7100.478
set A 5956.4596
set Iz 74375333.68

geomTransf Linear 1

element elasticBeamColumn 1 1 2 $A $E $Iz 1
element elasticBeamColumn 2 2 3 $A $E $Iz 1

set W1 -397560
set W2 397560

pattern Plain 1 Linear {
load 1 $W1 0 0 0 0 0
load 2 $W1 $W2 0 0 0 0
load 3 $W2 0 0 0 0 0
}

system BandGeneral
constraints Transformation
numberer RCM
algorithm Linear
integrator LoadControl 0.1
analysis Static

analyze 1
print

[fmk]

you can add temp loads to the 2d elastic beam column element .. for further
info on adding ele loads suggest you contact Maj. Scott Hamilton
Scott.Hamilton@usma.edu for assistance .