How do I change the releases of a beam element in a Staged Construction Analysis?

[aldoshoalv]

Hi everybody,

I am trying to model a precast concrete structure that needs to be analyzed in two stages. In the first of them, the structure has its beams simply supported at the ends by the columns. Then, when the concrete is poured into the node, the node will emulate a monolithic connection between the elements, thus, the beam will have certain restriction to the rotation.

For the first stage, I'm adding an equalDOF (in the directions 1 and 2, it's a 2D analysis) between the nodes of the end of the beam and the top of the column. Then I load my beam and run my analysis. Until here I have no problems.

The problem comes in the second stage, in which I add a zeroLengthSection at the ends of the beam to join it to the column, remove the equalDOF of the first stage (using remove mp) and add a new one that only acts in the direction 2. I am adding new loads to this stage and when I try to run the analysis it fails.

I think it's important to tell you that I am using a BeamColumnJoint element, that is why my model has 4 nodes per connection. Also my beam it's divided in 3 segments because it has different sections over its length.

This is the part of the script that I think it has the problem, I am not copying it all because it may lose focus. But if you want me to add another part that may be important, let me know... Thank you in advance!

puts "First analysis, beams simply supported"

# Nodes
node 1 0.0 0.0
node 2 $LBeam 0.0

fix 1 1 1 1
fix 2 1 1 1

node 101 0.0 [expr $LCol-$centi]
node 102 $LRigC $LCol
node 103 $LRigC $LCol
node 104 [expr -$LRigC] $LCol
node 108 [expr $LRigC+$LBeam/4.0] $LCol
node 110 0.0 [expr $LCol+$cents]
equalDOF 102 103 1 2

node 201 $LBeam [expr $LCol-$centi]
node 202 [expr $LBeam+$LRigC] $LCol
node 203 [expr $LBeam-$LRigC] $LCol
node 204 [expr $LBeam-$LRigC] $LCol
node 208 [expr $LBeam-($LRigC+$LBeam/4.0)] $LCol
node 210 $LBeam [expr $LCol+$cents]
equalDOF 203 204 1 2

# Elements
set IDColTransf 1
set IDBeamXTransf 2

set BeamXTransfType PDelta
set ColTransfType PDelta

geomTransf $ColTransfType $IDColTransf
geomTransf $BeamXTransfType $IDBeamXTransf

set numIntgrPts 5
set maxIters 3
set tolEl 1e-6

element nonlinearBeamColumn 1 1 101 $numIntgrPts $ColSecTag $IDColTransf -iter $maxIters $tolEl;
element nonlinearBeamColumn 2 2 201 $numIntgrPts $ColSecTag $IDColTransf -iter $maxIters $tolEl;

set eleHeightFac [expr 64./80.]
set eleWidthFac [expr 64./80.]
element beamColumnJoint 10 101 102 110 104 $BarSlipC $BarSlipC $CortanteC $BarSlipeB $BarSlipeT $CortanteB $Torsion $Torsion $Torsion $Torsion $Torsion $Torsion $ConfCol $eleHeightFac $eleWidthFac
element beamColumnJoint 20 201 202 210 203 $BarSlipC $BarSlipC $CortanteC $Torsion $Torsion $Torsion $Torsion $Torsion $Torsion $BarSlipeB $BarSlipeT $CortanteB $ConfCol $eleHeightFac $eleWidthFac

element nonlinearBeamColumn 102 103 108 $numIntgrPts $BeamSecTagE $IDBeamXTransf -iter $maxIters $tolEl
element nonlinearBeamColumn 103 108 208 $numIntgrPts $BeamSecTagI $IDBeamXTransf -iter $maxIters $tolEl
element nonlinearBeamColumn 104 208 204 $numIntgrPts $BeamSecTagE $IDBeamXTransf -iter $maxIters $tolEl

pattern Plain 101 Linear {
eleLoad -ele 1 2 -type -beamUniform 0 -$wCol; # Columnas
eleLoad -ele 102 103 104 -type -beamUniform -$wVigaSA; # VigasX
}

set Tol 1.0e-8;
constraints Transformation;
numberer Plain;
system UmfPack;
test NormDispIncr $Tol 6 ;
algorithm Newton;
set NstepGravity 10;
set DGravity [expr 1./$NstepGravity];
integrator LoadControl $DGravity;
analysis Static;
analyze $NstepGravity;


puts "Second analysis, beams without the end release"

remove mp 103
equalDOF 102 103 2

remove mp 204
equalDOF 203 204 2

element zeroLengthSection 101 102 103 $ZLESecTag
element zeroLengthSection 105 204 203 $ZLESecTag

pattern Plain 102 Linear {
eleLoad -ele 102 103 104 -type -beamUniform -$wVigaEmp; # VigasX
}

analyze $NstepGravity;

loadConst -time 0.0