How to model a post tension column

[bahramabdollahi]

hello everyone
I modeled a post tensioned concrete column with Concrete04 & TendonL01 materials then I confronted an error message when I ran cyclic analysis.
here is the error message :
WARNING: CTestNormDispIncr::test() - failed to converge
after: 10 iterations current Norm: 3.29944e-006 (max: 1e-006, Norm deltaR: 1110.68)
NewtnRaphson::solveCurrentStep() -the ConvergenceTest object failed in test()
StaticAnalysis::analyze() - the Algorithm failed at iteration: 3950 with domain at load factor 36.1053
OpenSees > analyze failed, returned: -3 error flag

would you please help me

and here is the code

wipe
wipe analysis

# Precast Segmental Bridge Columns

model BasicBuilder -ndm 2 -ndf 3
file mkdir Data-PostTension-Cyclic; # create data directory


# Define variables =================
# Constants

set PI [expr 2*asin(1.0)];


# ========== Material Tags =============

set IDconU 1; # Material Tag of unconfined concrete
set IDconC 2; # Material Tag of confined concrete
set IDreinf 3; # Material Tag of reinforcement
set IDTendon 4; # Material Tag of prestress steel


# ============ Cordinates ===========

node 1 0.0 0.0;
node 2 0.0 1600.0;


# ========== Boundary conditions ============

fix 1 1 1 1


# =======================================================
# ================= Define materials ====================
# ================= Concrete Materials ==================

# Nominal concrete compressive strength
set fcU -66.50;

# Concrete strength(Core)
set fc -78.613894;
set Ec [expr 3320.0*sqrt(-$fc)+6900.0];

# -------------------- Unconfined concrete
set fc1U $fcU;
set eps1U -0.001975;
set eps2U [expr 2.0*$eps1U];

uniaxialMaterial Concrete04 $IDconU $fc1U $eps1U $eps2U $Ec

# -------------------- Confined concrete
set fc1c $fc;
set eps1c -0.0037402;
set eps2c -0.012;

uniaxialMaterial Concrete04 $IDconC $fc1c $eps1c $eps2c $Ec


# =======================================================================
# ==================== Reinforcing Steel Materials ======================
# -------------------- Reinforcing steel
set fy 317.00;
set Er 200000.0;
set b 0.1;
set R0 18.0;
set cR1 0.925;
set cR2 0.15;

uniaxialMaterial Steel02 $IDreinf $fy $Er $b $R0 $cR1 $cR2


# --------------------- Prestress steel
set Ep 200000.0;
set fyp 1600.0;
set fpc 1870.0;
set rou 0.016332;
set epsi 0.00375;

# ------------------------- tag------fy----E0--fpc---b---epsi
uniaxialMaterial TendonL01 $IDTendon $fyp $Ep $fpc $rou $epsi

# ======================================================================
# =============== Create a Uniaxial Fiber object =======================

set SecWidth 350; # width of the section
set SecDepth 350; # depth of the section
set cover [expr 24.0+6.0+5.0]; # concrete cover
set DiaBar 10; # longitudianl bar diameter
set AreaBar [expr $PI*pow($DiaBar,2)/4]; # area of the longitudianl bar
set DiaStirrup 11.2272; #diameter of stirrups
set AreaBarP [expr $PI*pow($DiaStirrup,2)/4]; #distance from the beginning of the web to the first reinf. bar


#coordiantes for steel layers--------------------------

set cz1 [expr $SecDepth/2.0]; # Variables derived from the parameters
set cy1 [expr $SecWidth/2.0]; # Variables derived from the parameters


section Fiber 1 {
# Create the concrete core fibers
patch rect $IDconC 5 5 [expr $cover-$cy1] [expr $cover-$cz1] [expr $cy1-$cover] [expr $cz1-$cover];
# Create the concrete cover fibers (top, bottom, left, right)
patch rect $IDconU 5 2 -$cy1 [expr $cz1-$cover] $cy1 $cz1;
patch rect $IDconU 5 2 -$cy1 -$cz1 $cy1 [expr $cover-$cz1];
patch rect $IDconU 2 5 -$cy1 [expr $cover-$cz1] [expr $cover-$cy1] [expr $cz1-$cover];
patch rect $IDconU 2 5 [expr $cy1-$cover] [expr $cover-$cz1] $cy1 [expr $cz1-$cover];
# Create the reinforcing fibers (5 layers)
# ------------ $matTag---$number of bars---$area of one bar---$start cordinates and end cordinates
layer straight $IDreinf 5 $AreaBar [expr $cover-$cy1] [expr $cz1-$cover] [expr $cy1-$cover] [expr $cz1-$cover];
layer straight $IDreinf 2 $AreaBar [expr $cover-$cy1] [expr $cz1-$cover-70] [expr $cy1-$cover] [expr $cz1-$cover-70];
layer straight $IDreinf 2 $AreaBar [expr $cover-$cy1] 0.0 [expr $cy1-$cover] 0.0;
layer straight $IDreinf 2 $AreaBar [expr $cover-$cy1] [expr -($cz1-$cover-70)] [expr $cy1-$cover] [expr -($cz1-$cover-70)];
layer straight $IDreinf 5 $AreaBar [expr $cover-$cy1] [expr $cover-$cz1] [expr $cy1-$cover] [expr $cover-$cz1];
}


# ===============================================
# Create column
# ===============================================

geomTransf Corotational 1

# --------------------- $eleTag $iNode $jNode $numIntgrPts $secTag $transfTag
element nonlinearBeamColumn 1 1 2 10 1 1
element truss 2 1 2 1.0 $IDTendon

# ================================================
# =================== Recorders ==================

recorder Node -file Data-PostTension-Cyclic/Displacement.out -time -node 2 -dof 1 disp
recorder Node -file Data-PostTension-Cyclic/React.out -time -node 1 -dof 1 reaction

#recorder plot $filename $windowtitle $xloc $yloc $xpixels $ypixels -column $xcol $ycol
recorder plot Data-PostTension-Cyclic/Displacement.out Displacement 550 0 800 600 -columns 2 1

recorder display "Column" 0 0 500 500 -wipe
prp 0 0 1;
vup 0 1 0;
vpn 0 0 1;
viewWindow -1800 1800 -1800 1800
display 1 -1 10


# ================================================
puts "========== Model Builded ! ==========="
# ================================================
# ============== Constant Loading ================

pattern Plain 1 Constant {
load 2 0.0 -300000.0 0.0
}

constraints Plain ;
numberer RCM ;
system BandGeneral ;
test NormDispIncr 1.e-5 10 ;
algorithm ModifiedNewton ;
integrator LoadControl 1 ;
analysis Static ;
analyze 1 ;
loadConst -time 0.0 ;


# =======================================
# Start of analysis generation
# =======================================
# =========== Cyclic Loading ============

pattern Plain 2 Linear {
load 2 100.0 0.0 0.0
}

constraints Plain
numberer RCM
system BandGeneral
test NormDispIncr 1.e-6 10
algorithm ModifiedNewton
analysis Static

for {set i 1} {$i<4} {incr i 1} {
integrator DisplacementControl 2 1 0.8
analyze 10;
integrator DisplacementControl 2 1 -1.6
analyze 10;
integrator DisplacementControl 2 1 0.8
analyze 10;
}
for {set i 1} {$i<4} {incr i 1} {
integrator DisplacementControl 2 1 1.2
analyze 10;
integrator DisplacementControl 2 1 -2.4
analyze 10;
integrator DisplacementControl 2 1 1.2
analyze 10;
}
for {set i 1} {$i<4} {incr i 1} {
integrator DisplacementControl 2 1 1.6
analyze 10;
integrator DisplacementControl 2 1 -3.2
analyze 10;
integrator DisplacementControl 2 1 1.6
analyze 10;
}
for {set i 1} {$i<4} {incr i 1} {
integrator DisplacementControl 2 1 2.4
analyze 10;
integrator DisplacementControl 2 1 -4.8
analyze 10;
integrator DisplacementControl 2 1 2.4
analyze 10;
}
for {set i 1} {$i<4} {incr i 1} {
integrator DisplacementControl 2 1 3.2
analyze 10;
integrator DisplacementControl 2 1 -6.4
analyze 10;
integrator DisplacementControl 2 1 3.2
analyze 10;
}
for {set i 1} {$i<4} {incr i 1} {
integrator DisplacementControl 2 1 4.0
analyze 10;
integrator DisplacementControl 2 1 -8.0
analyze 10;
integrator DisplacementControl 2 1 4.0
analyze 10;
}
for {set i 1} {$i<4} {incr i 1} {
integrator DisplacementControl 2 1 4.8
analyze 10;
integrator DisplacementControl 2 1 -9.6
analyze 10;
integrator DisplacementControl 2 1 4.8
analyze 10;
}
for {set i 1} {$i<4} {incr i 1} {
integrator DisplacementControl 2 1 5.6
analyze 10;
integrator DisplacementControl 2 1 -11.2
analyze 10;
integrator DisplacementControl 2 1 5.6
analyze 10;
}
for {set i 1} {$i<4} {incr i 1} {
integrator DisplacementControl 2 1 7.2
analyze 10;
integrator DisplacementControl 2 1 -14.4
analyze 10;
integrator DisplacementControl 2 1 7.2
analyze 10;
}


#===============================================
puts "======== Analysis Completed !======="
# ==============================================

thank you

[fmk]

the model gets part way through the analysis .. try something if the analysis fails.

http://opensees.berkeley.edu/wiki/index ... r_Analysis

[bahramabdollahi]

Thank you dear fmk , It works.