section aggregator

[Olympia]

Hello,
I'm trying to simulate a bridge in 3d space. I used fiber section for the pier. In an effort to assign torsional Stiffness for my 3D Model, i used the section Aggregator. Unfortunately,it doesn't seem to work properly. I take the message:
ForceBeamColumn 3D:: no torsion detected in sections, continuing with element torsional stiffness GJ/L =1e10

I would appreciate if you could help me.
Here is my model:


# SET UP ----------------------------------------------------------------------------
wipe; # clear memory of all past model definitions
model BasicBuilder -ndm 3 -ndf 6; # Define the model builder, ndm=#dimension, ndf=#dofs
set dataDir Model1
file mkdir $dataDir

# ==============================================================================
# Define NODES
# ==============================================================================
# nodal coordinates
# NODES of Deck
node 31 63.434 0. 0.
node 30 62.014 0. 0.
node 29 60.594 0. 0.
node 28 58.1365 0. 0.
node 27 55.679 0. 0.
node 26 53.2215 0. 0.
node 25 50.764 0. 0.
node 24 48.174 0. 0.
node 23 45.719 0. 0.
node 22 43.264 0. 0.
node 21 41.1315 0. 0.
node 20 38.999 0. 0.
node 19 36.8665 0. 0.
node 18 34.734 0. 0.
node 17 33.2255 0. 0.
node 16 31.717 0. 0.
node 15 30.2085 0. 0.
node 14 28.7 0. 0.
node 13 26.5675 0. 0.
node 12 24.435 0. 0.
node 11 22.3025 0. 0.
node 10 20.17 0. 0.
node 9 17.715 0. 0.
node 8 15.26 0. 0.
node 7 12.67 0. 0.
node 6 10.2125 0. 0.
node 5 7.755 0. 0.
node 4 5.2975 0. 0.
node 3 2.84 0. 0.
node 2 1.42 0. 0.
node 1 0. 0. 0.

# NODES of pier
node 101 31.717 -0.84 0.
node 102 31.717 -1.03622 0.
node 103 31.717 -1.23244 0.
node 104 31.717 -1.62488 0.
node 105 31.717 -2.40975 0.
node 106 31.717 -3.9795 0.
node 107 31.717 -5.54925 0.
node 108 31.717 -6.33413 0.
node 109 31.717 -6.72656 0.
node 110 31.717 -6.92278 0.
node 111 31.717 -7.119 0.


# ==============================================================================
# Define SECTIONS
# ==============================================================================
# define section tags:
set DeckSpanSecTag1 2
set DeckSpanSecTag2 3
set DeckSpanSecTag3 4
set RigidSecTag 5

# material properties:
set Ec 21525560; # concrete Young Modulus
set nu 0.2; # Poisson ratio
set Gc [expr $Ec/2./[expr 1+$nu]]; # Shear Modulus

# ----------------------------------------------------------
# DEFINE DECK Section Properties
# ----------------------------------------------------------
# DECK SECTION No1
set AgDeckSpan1 4.535; # DECK cross-sectional area
set IzDeckSpan1 128.86; # about-local-z Rect-Deck (un)cracked moment of inertia
set IyDeckSpan1 2.016; # about-local-y Rect-Deck (un)cracked moment of inertia
set JbSpan1 10.159; # Torsional constant. Big number in the example
# DECK SECTION No2
set AgDeckSpan2 14.361; # DECK cross-sectional area
set IzDeckSpan2 89.620; # about-local-z Rect-Deck (un)cracked moment of inertia
set IyDeckSpan2 3.519; # about-local-y Rect-Deck (un)cracked moment of inertia
set JbSpan2 10.159; # Torsional constant. Big number in the example
# DECK SECTION No3
set AgDeckSpan3 3.983; # DECK cross-sectional area
set IzDeckSpan3 36.925; # about-local-z Rect-Deck (un)cracked moment of inertia
set IyDeckSpan3 1.92; # about-local-y Rect-Deck (un)cracked moment of inertia
set JbSpan3 10.159; # Torsional constant. Big number in the example
# RIGID section
set AgRigid 10000; # Column cross-sectional area
set IzRigid 10000; # about-local-z Rect-Deck (un)cracked moment of inertia
set IyRigid 10000; # about-local-y Rect-Deck (un)cracked moment of inertia
set JbRigid 10000; # Torsional constant. Big number in the example

section Elastic $DeckSpanSecTag1 $Ec $AgDeckSpan1 $IzDeckSpan1 $IyDeckSpan1 $Gc $JbSpan1
section Elastic $DeckSpanSecTag2 $Ec $AgDeckSpan2 $IzDeckSpan2 $IyDeckSpan2 $Gc $JbSpan2
section Elastic $DeckSpanSecTag3 $Ec $AgDeckSpan3 $IzDeckSpan3 $IyDeckSpan3 $Gc $JbSpan3
section Elastic $RigidSecTag $Ec $AgRigid $IzRigid $IyRigid $Gc $JbRigid

# ----------------------------------------------------------
# DEFINE PIER Section Properties
# ----------------------------------------------------------
# MATERIAL parameters
set IDconcCorePier 30; # material ID tag -- confined core concrete
set IDconcCoverPier 31; # material ID tag -- unconfined cover concrete
set IDreinfPier 32; # material ID tag -- reinforcement
# -----------
set FyPier 280000; # STEEL yield stress 62ksi=413685kPa*1.1=455055kPa
set eyPier 0.0014;
set EsPier [expr $FyPier/$eyPier]; # modulus of steel
set FuPier 350000;
set euPier 0.025;
set bPier [expr ($FuPier-$FyPier)/($euPier-$eyPier)/$FyPier*$eyPier]; # strain-hardening ratio (ratio between post-yield tangent and initial elastic tangent)

uniaxialMaterial Steel01 $IDreinfPier $FyPier $EsPier $bPier;

uniaxialMaterial Concrete01 $IDconcCoverPier -20684 -0.002 -17581 -0.0035;
uniaxialMaterial Concrete01 $IDconcCorePier -24821 -0.004 -20000 -0.02;

# SECTION GEOMETRY -------------------------------------------------------------
set PierSecTag 1; # set tag for symmetric section
set DSecPier 1.524; # Column Diameter
set coverSecPier 0.15; # Column cover to reinforcing steel
set numBarsSecPier 18; # number of uniformly-distributed longitudinal-reinforcement bars
set barAreaSecPier 0.00258; # area of longitudinal-reinforcement bars

# Generate a circular reinforced concrete section
# with ONE layer of steel evenly distributed around the perimeter and a confined core.
# confined core.
# by: Michael H. Scott, 2003
# Notes
# The center of the reinforcing bars are placed at the inner radius
# The core concrete ends at the inner radius (same as reinforcing bars)
# The reinforcing bars are all the same size
# The center of the section is at (0,0) in the local axis system
# Zero degrees is along section y-axis

set riPier 0.0; # inner radius of the section, only for hollow sections
set roPier [expr $DSecPier/2]; # overall (outer) radius of the section
set nfCoreRPier 10; # number of radial divisions in the core (number of "rings")
set nfCoreTPier 20; # number of theta divisions in the core (number of "wedges")
set nfCoverRPier 2; # number of radial divisions in the cover
set nfCoverTPier 20; # number of theta divisions in the cover

# Define the fiber section
section fiberSec $PierSecTag {
set rcPier [expr $roPier-$coverSecPier]; # Core radius
patch circ $IDconcCorePier $nfCoreTPier $nfCoreRPier 0 0 $riPier $rcPier 0 360; # Define the core patch
patch circ $IDconcCoverPier $nfCoverTPier $nfCoverRPier 0 0 $rcPier $roPier 0 360; # Define the cover patch
set thetaPier [expr 360.0/$numBarsSecPier]; # Determine angle increment between bars
layer circ $IDreinfPier $numBarsSecPier $barAreaSecPier 0 0 $rcPier $thetaPier 360; # Define the reinforcing layer
}

# assign torsional Stiffness for 3D Model
set SecTagTorsionPier 200; # ID tag for torsional section behavior
set SecTag3DPier 201; # ID tag for combined behavior for 3D model
set UbigPier 1.e10; # a really large number
uniaxialMaterial Elastic $SecTagTorsionPier $UbigPier; # define elastic torsional stiffness
section Aggregator $SecTag3DPier $SecTagTorsionPier T -section $PierSecTag; # combine section properties (assign torsional Stiffness for 3D Model)


# ==============================================================================
# Define ELEMENTS
# ==============================================================================
# set up geometric transformations of element
# separate columns and beams, in case of P-Delta analysis for columns
# in 3D model, assign vector vecxz
set IDColTransf 1; # all columns (piers) will have the same transformation
set IDDeckTransf 2; # all deck beams will have the same transformation

# It is absolutely necessary to define the transformation of the local to the global
# axes properly in order to translate the correct local stiffness of the elements
# (which also use local Z-Y axes)
geomTransf Linear $IDColTransf 0 0 1;
geomTransf Linear $IDDeckTransf 0 -1 0;

# Define Beam-Column Elements
set np 5; # number of Gauss integration points for nonlinear curvature distribution
# DECK
element nonlinearBeamColumn 1 1 2 $np $DeckSpanSecTag1 $IDDeckTransf -mass 0.00; # Element 1
element nonlinearBeamColumn 2 2 3 $np $DeckSpanSecTag1 $IDDeckTransf -mass 0.00; # Element 2
element nonlinearBeamColumn 3 3 4 $np $DeckSpanSecTag3 $IDDeckTransf -mass 0.00; # Element 3
element nonlinearBeamColumn 4 4 5 $np $DeckSpanSecTag3 $IDDeckTransf -mass 0.00; # Element 4
element nonlinearBeamColumn 5 5 6 $np $DeckSpanSecTag3 $IDDeckTransf -mass 0.00; # Element 5
element nonlinearBeamColumn 6 6 7 $np $DeckSpanSecTag3 $IDDeckTransf -mass 0.00; # Element 6
element nonlinearBeamColumn 7 7 8 $np $DeckSpanSecTag1 $IDDeckTransf -mass 0.00; # Element 7
element nonlinearBeamColumn 8 8 9 $np $DeckSpanSecTag3 $IDDeckTransf -mass 0.00; # Element 8
element nonlinearBeamColumn 9 9 10 $np $DeckSpanSecTag3 $IDDeckTransf -mass 0.00; # Element 9
element nonlinearBeamColumn 10 10 11 $np $DeckSpanSecTag1 $IDDeckTransf -mass 0.00; # Element 10
element nonlinearBeamColumn 11 11 12 $np $DeckSpanSecTag1 $IDDeckTransf -mass 0.00; # Element 11
element nonlinearBeamColumn 12 12 13 $np $DeckSpanSecTag1 $IDDeckTransf -mass 0.00; # Element 12
element nonlinearBeamColumn 13 13 14 $np $DeckSpanSecTag1 $IDDeckTransf -mass 0.00; # Element 13
element nonlinearBeamColumn 14 14 15 $np $DeckSpanSecTag2 $IDDeckTransf -mass 0.00; # Element 14
element nonlinearBeamColumn 15 15 16 $np $DeckSpanSecTag2 $IDDeckTransf -mass 0.00; # Element 15
element nonlinearBeamColumn 16 16 17 $np $DeckSpanSecTag2 $IDDeckTransf -mass 0.00; # Element 16
element nonlinearBeamColumn 17 17 18 $np $DeckSpanSecTag2 $IDDeckTransf -mass 0.00; # Element 17
element nonlinearBeamColumn 18 18 19 $np $DeckSpanSecTag1 $IDDeckTransf -mass 0.00; # Element 18
element nonlinearBeamColumn 19 19 20 $np $DeckSpanSecTag1 $IDDeckTransf -mass 0.00; # Element 19
element nonlinearBeamColumn 20 20 21 $np $DeckSpanSecTag1 $IDDeckTransf -mass 0.00; # Element 20
element nonlinearBeamColumn 21 21 22 $np $DeckSpanSecTag1 $IDDeckTransf -mass 0.00; # Element 21
element nonlinearBeamColumn 22 22 23 $np $DeckSpanSecTag3 $IDDeckTransf -mass 0.00; # Element 22
element nonlinearBeamColumn 23 23 24 $np $DeckSpanSecTag3 $IDDeckTransf -mass 0.00; # Element 23
element nonlinearBeamColumn 24 24 25 $np $DeckSpanSecTag1 $IDDeckTransf -mass 0.00; # Element 24
element nonlinearBeamColumn 25 25 26 $np $DeckSpanSecTag3 $IDDeckTransf -mass 0.00; # Element 25
element nonlinearBeamColumn 26 26 27 $np $DeckSpanSecTag3 $IDDeckTransf -mass 0.00; # Element 26
element nonlinearBeamColumn 27 27 28 $np $DeckSpanSecTag3 $IDDeckTransf -mass 0.00; # Element 27
element nonlinearBeamColumn 28 28 29 $np $DeckSpanSecTag3 $IDDeckTransf -mass 0.00; # Element 28
element nonlinearBeamColumn 29 29 30 $np $DeckSpanSecTag1 $IDDeckTransf -mass 0.00; # Element 29
element nonlinearBeamColumn 30 30 31 $np $DeckSpanSecTag1 $IDDeckTransf -mass 0.00; # Element 30
# PIERS
element nonlinearBeamColumn 31 101 102 $np $PierSecTag $IDColTransf; # Element 31

Many thanks in advance!
Oly.

[vesna]

you defined a pier using a fiber section with the tag $PierSecTag which does not include torsion. replace it with a tag of your section aggregator $SecTag3DPier.