stdBrick - truss element assembly

[aylsworth]

Hi,

I am trying to model the on shown in the photo link below:

https://drive.google.com/open?id=0BzIal ... U5wM3JZcXc

I am trying to model it by using a stdBrick element for the prismatic column (8 nodes defined - disregarding the vertical links) connected by 8 diagonal truss elements (I just used truss element to defined these materials but it should be axial springs with user defined degrading bilinear hysteretic rule). There will be an axial load applied on the column. However, it seems that the analysis is not converging. What should I do?

I also tried twoNodeLink but still it is not functioning.


wipe; # clear memory of all past model definitions

set dataDir ArakawaOA2_Palacio; # set up name of data directory
file mkdir $dataDir; # create data directory

model BasicBuilder -ndm 3 -ndf 6; # Define the model builder, ndm=#dimension, ndf=#dofs

# define GEOMETRY -------------------------------------------------------------
set LCol 225.0; # column length in mm
set Weight 190000.0; # superstructure weight
# define section geometry
set HCol 180.0; # Column Depth in mm
set BCol 180.0; # Column Width in mm

# nodal coordinates:
#Brickelement
node 1 [expr $BCol/2] $LCol [expr $HCol/2]; # node X, Y
node 4 [expr $BCol/2] $LCol [expr -$HCol/2];
node 3 [expr -$BCol/2] $LCol [expr -$HCol/2];
node 2 [expr -$BCol/2] $LCol [expr $HCol/2];
node 5 [expr $BCol/2] $Lpi [expr $HCol/2]; # node X, Y
node 6 [expr $BCol/2] $Lpi [expr -$HCol/2];
node 7 [expr -$BCol/2] $Lpi [expr -$HCol/2];
node 8 [expr -$BCol/2] $Lpi [expr $HCol/2];

#Support
node 9 [expr $BCol/2] 0.0 [expr $HCol/2]; # node X, Y
node 10 [expr $BCol/2] 0.0 [expr -$HCol/2];
node 11 [expr -$BCol/2] 0.0 [expr -$HCol/2];
node 12 [expr -$BCol/2] 0.0 [expr $HCol/2];

# Single point constraints -- Boundary Conditions
fix 9 1 1 1 0 0 0; # node DX DY RZ
fix 10 1 1 1 0 0 0; # node DX DY RZ
fix 11 1 1 1 0 0 0; # node DX DY RZ
fix 12 1 1 1 0 0 0; # node DX DY RZ


#Defining primatic column
set brickmaterial 20
set brickelement 21
nDMaterial ElasticIsotropic $brickmaterial $Ec 0.15
element stdBrick $brickelement 5 6 7 8 1 2 3 4 $brickmaterial

#Defining spring configuration
element truss 30 12 5 1.0 $diagonalspring
element truss 31 9 8 1.0 $diagonalspring
element truss 32 9 6 1.0 $diagonalspring
element truss 33 10 5 1.0 $diagonalspring
element truss 34 10 7 1.0 $diagonalspring
element truss 35 11 6 1.0 $diagonalspring
element truss 36 12 7 1.0 $diagonalspring
element truss 37 11 8 1.0 $diagonalspring

#element twoNodeLink 30 12 5 -mat $diagonalspring -dir 1;
#element twoNodeLink 31 9 8 -mat $diagonalspring -dir 1;
#element twoNodeLink 32 9 6 -mat $diagonalspring -dir 1;
#element twoNodeLink 33 5 10 -mat $diagonalspring -dir 1;
#element twoNodeLink 34 10 7 -mat $diagonalspring -dir 1;
#element twoNodeLink 35 11 6 -mat $diagonalspring -dir 1;
#element twoNodeLink 36 12 7 -mat $diagonalspring -dir 1;
#element twoNodeLink 37 11 8 -mat $diagonalspring -dir 1;

# define GRAVITY -------------------------------------------------------------
pattern Plain 1 Linear {
load 1 0 [expr -$PCol/4.0] 0 0 0 0
load 2 0 [expr -$PCol/4.0] 0 0 0 0
load 3 0 [expr -$PCol/4.0] 0 0 0 0
load 4 0 [expr -$PCol/4.0] 0 0 0 0
}

# Gravity-analysis parameters -- load-controlled static analysis
set Tol 1.0e-6; # convergence tolerance for test
constraints Transformation; # how it handles boundary conditions
numberer RCM; # renumber dof's to minimize band-width (optimization), if you want to
system BandGeneral; # how to store and solve the system of equations in the analysis
test NormDispIncr $Tol 6 ; # determine if convergence has been achieved at the end of an iteration step
algorithm Newton; # use Newton's solution algorithm: updates tangent stiffness at every iteration
set NstepGravity 10; # apply gravity in 10 steps
set DGravity [expr 1./$NstepGravity]; # first load increment;
integrator LoadControl $DGravity; # determine the next time step for an analysis
analysis Static; # define type of analysis static or transient

# Do analysis for axial load
set ok [analyze $NstepGravity]; # 0: if successful, <0 if NOT successful

if { $ok<0 } {
puts "Unsuccessful convergence!"
} else {
puts "Axial load analysis converged successfully!"
puts " ";
}

# ------------------------------------------------- maintain constant gravity loads and reset time to zero
loadConst -time 0.0


Hoping for someone to help me with this issue. Thank you very much.

Patrick