how to difine the "fix" command of the zerolengthsection

[uyupeng]

Hello,everyone
I build a canticolumn model with zerolengthsection whose reinforcement bars are modeled with bond_slip material under cycle load

If i deifine "fix 2 1 0 0"(the zerolengthsection can't resist shear so i fix the 1st dof),I will get the following warning:
-------------------------------------------------------------------------------------------------------------------
WARNING: CTestNormDispIncr::test() - failed to converge
after: 1000 iterations current Norm: 2.27057e+013 (max: 1e-006, Norm deltaR: 134.89)
AcceleratedNewton::solveCurrentStep() -The ConvergenceTest object failed in test()
StaticAnalysis::analyze() - the Algorithm failed at iteration: 0 with domain at load factor 0
OpenSees > analyze failed, returned: -3 error flag
WARNING SuperLU::solve(void)- Error 16 returned in factorization dgstrf()
WARNING AcceleratedNewton::solveCurrentStep() -the LinearSysOfEqn failed in solve()
StaticAnalysis::analyze() - the Algorithm failed at iteration: 0 with domain at load factor 690.065
OpenSees > analyze failed, returned: -3 error flag
-------------------------------------------------------------------------------------------------------------------
But when i change the fix command the programe goes well without the mentiond warning, however the result does't fit correctly.
Looking forward dear yours reply!





# Cantilever Column
# -----------------
# Units: kips, in.

# Cyclic analysis five dispBeamColumn + one zeroLengthSection

# modeling the cirvular RC column (FL3) tested by
# Saatcioglu, M., Alsiwat, J. and Ozcebe, G.
# "Hysteretic Behavior of Anchorage Slip in R/C Members,"
# Journal of Structural Engineering, V. 118, No. 9, 1992, pp. 2439-2458.

wipe
logFile log.out
# Create ModelBuilder (with two dimensions and 2 DOF/node)
model basic -ndm 2 -ndf 3

# Create nodes
# tag X Y
node 1 0.0 0.0
node 2 0.0 0.0
node 3 0.0 7.88
node 4 0.0 15.76
node 5 0.0 23.64
node 6 0.0 31.52
node 7 0.0 39.4

# Fix supports at base of column
# Tag DX DY RZ
fix 1 1 1 1
fix 2 1 0 0
# equalDOF 1 2 1

# Define materials for nonlinear columns
## Core concrete (confined)
##CONCRETE tag f'c ec0 f'cu ecu
uniaxialMaterial Concrete01 1 -7.57 -0.006 -6.06 -0.014

## Cover concrete (unconfined)
##CONCRETE tag f'c ec0 f'cu ecu
uniaxialMaterial Concrete01 2 -5.41 -0.002 0.0 -0.006

## STEEL rebar
##STEEL02 tag $Fy $E $b $R0 $cR1 $cR2 $a1 $a2 $a3 $a4
uniaxialMaterial Steel02 3 63.5 29000 0.01 18.5 0.925 0.15 0.00 1.0 0.00 1.0

#uniaxialMaterial StrPen01 $Tag $fy $sy $fu $su $b $R
uniaxialMaterial Bond_SP01 5 63.4 0.022 95.1 0.77 0.4 1.0

# Define cross-section for nonlinear column
## Set some parameters
set colDia 13.8; # bending in this direction (local and global y)
set cover 1.08;
set bcent 1.77; # [expr $cover+0.197+0.5]
set As 0.79; # Area of no. 8 bar

set a [expr $colDia/2.0]
set b [expr $colDia/2.0-$cover]
set c [expr $colDia/2.0-$bcent]

section Fiber 1 {
# core concrete fibers
patch quad 1 12 12 -$b -$b $b -$b $b $b -$b $b
# concrete cover fibers
patch quad 2 16 2 -$a -$a $a -$a $a -$b -$a -$b
patch quad 2 16 2 -$a $b $a $b $a $a -$a $a
patch quad 2 2 12 -$a -$b -$b -$b -$b $b -$a $b
patch quad 2 2 12 $b -$b $a -$b $a $b $b $b
# reinforcing fibers
layer straight 3 3 $As -$c -$c -$c $c
layer straight 3 3 $As $c -$c $c $c
layer straight 3 2 $As 0 -$c 0 $c
}

section Fiber 2 {
# core concrete fibers
patch quad 1 12 12 -$b -$b $b -$b $b $b -$b $b
# concrete cover fibers
patch quad 2 16 2 -$a -$a $a -$a $a -$b -$a -$b
patch quad 2 16 2 -$a $b $a $b $a $a -$a $a
patch quad 2 2 12 -$a -$b -$b -$b -$b $b -$a $b
patch quad 2 2 12 $b -$b $a -$b $a $b $b $b
# reinforcing fibers ！！！！！！！！！！！！！！！
layer straight 5 3 $As -$c -$c -$c $c
layer straight 5 3 $As $c -$c $c $c
layer straight 5 2 $As 0 -$c 0 $c
}

# Define column elements
## Geometry of coloumn elements
geomTransf Linear 1

# Number of integration points along length of element
set np 5

# Create the columns using displacement controlled beam-column elements
# tag ndI ndJ secID
element zeroLengthSection 1 1 2 2
# tag ndI ndJ nsecs secID transfTag
element dispBeamColumn 2 2 3 $np 1 1
element dispBeamColumn 3 3 4 $np 1 1
element dispBeamColumn 4 4 5 $np 1 1
element dispBeamColumn 5 5 6 $np 1 1
element dispBeamColumn 6 6 7 $np 1 1
# puts "here?"
# Set up and perform analysis
## Create recorders
recorder Node -file topdisp.out -time -nodeRange 1 6 -dof 1 disp
recorder Element -file secstrs.out -time -ele 2 section 1 fiber -$c 0 3 stressStrain
recorder Element -file secstrc.out -time -ele 2 section 1 fiber $b 0 2 stressStrain
recorder Element -file secforce.out -time -ele 1 deformation

# recorder display "Display" xLoc yLoc xPixels yPixels -wipe
recorder display "Display" 5 5 630 630 -wipe
# "normal" vector to the view window
vpn +0.000000E+000 +0.000000E+000 +1.000000E+000
# "up" vector of the view window
vup +0.000000E+000 +1.000000E+000 +0.000000E+000
# Projection Reference Point (direction vector to the eye)
prp +0.000000E+000 +0.000000E+000 +1.000000E+000
# dimension of the view window
viewWindow -5.000 +5.000 -5.000 +50.000
# center of the view window
vrp +0.000 +0.000 +0.000000E+000
# display elemDispOpt nodeDispOpt magFactor
display 1 3 +4.000000E+000

set P -134.89
pattern Plain 1 "Constant" {
load 7 0.0 $P 0.0
}

# Define analysis parameters
integrator LoadControl 0
system SparseGeneral -piv
test NormDispIncr 1.0e-6 1000
numberer Plain
constraints Plain
algorithm KrylovNewton
analysis Static

# Do one analysis for constant axial load
analyze 1

# Define reference force
pattern Plain 2 "Linear" {
load 7 1.0 0.0 0.0
}

# Compute displacement increment
set dU 0.005

# Perform the analysis
# integrator DisplacementControl $node $dof $incr <$numIter $ΔUmin $ΔUmax>
integrator DisplacementControl 7 1 $dU
analyze 86
integrator DisplacementControl 7 1 -$dU
analyze 172
integrator DisplacementControl 7 1 $dU
analyze 86

integrator DisplacementControl 7 1 $dU
analyze 180
integrator DisplacementControl 7 1 -$dU
analyze 360
integrator DisplacementControl 7 1 $dU
analyze 180

integrator DisplacementControl 7 1 $dU
analyze 360
integrator DisplacementControl 7 1 -$dU
analyze 720
integrator DisplacementControl 7 1 $dU
analyze 360

integrator DisplacementControl 7 1 $dU
analyze 540
integrator DisplacementControl 7 1 -$dU
analyze 1080
integrator DisplacementControl 7 1 $dU
analyze 540

integrator DisplacementControl 7 1 $dU
analyze 720
integrator DisplacementControl 7 1 -$dU
analyze 1440
integrator DisplacementControl 7 1 $dU
analyze 720

[fmk]

when you define a section for use in a zeroLength element you must provide a force-rotation relation, when providing to the beam elements you provide a force-curvature relation.

[uyupeng]

Dear fmk,@fmk
Thank you for your kindly reply.
I understand what you mean the use of zeroLength. But here I want to use the command:zeroLengthSection to define a fiber section(zerolength) whose force-rotation relation can be included in the fiber section.
As for the script upon, which part leads to the warning?

thank you

[uyupeng]

well, it may be the orient's question...
element zeroLengthSection $eleTag $iNode $jNode $secTag <-orient $x1 $x2 $x3 $yp1 $yp2 $yp3> <-doRayleigh $rFlag>

[zhouchaofeng]

hello! Recently i am studying the zerolengthsection, i have some problems, so i hope you can help me, i will appreciate you very much!!!

[fmk]

back to thr original question .. what did you change the fix command too that caused you to get answers, albeit incorrect ones?