The OpenSees Community

Thank you, I'll check.

Andrea

Hi Gor,

thanks for your replay. I will play a little bit.

Grazie mille

Dear all,

I'm interested in looking at the analytical equations which govern the change in state of the Pinching4 material. Where I can find it?

Thanks for the attention.

Andrea

Now I have a linear decrease of the amplitude, but when the restoring force is lower than the friction forces there are vibrations (with constant amplitude) instead to have a constant residual displacement. Someone can help me? Thanks
Below there is an update of the code:


wipe;
source Units.tcl
model basic -ndm 2 -ndf 2

set dispSeries "Linear -factor 0.005"

node 1 0.0 0.0
node 2 0.0 0.0

set M 0.1

set nEig 1
fix 1 1 1

set K 1000
set matTag 1
uniaxialMaterial Elastic $matTag $K

set eleTag 1
set dirTag 1
element zeroLength $eleTag 1 2 -mat $matTag -dir $dirTag

#---------------------------------------------------------------------------------------
#CONTACT ELEMENT
# model basic -ndm 2 -ndf 2;

node 3 0. 0.
node 4 0. 0.

equalDOF 1 3 1 2
equalDOF 2 4 1 2


set mu1 0.10

set normalX 0
set normalY 1
set Kn 1.0e+10
set Kt $K

element zeroLengthContact2D 2 4 3 $Kn $Kt $mu1 -normal $normalX $normalY
#---------------------------------------------------------------------------------------

mass 4 $M 0.0
set IDnode 4
set IDdir 1
recorder Node -file Spostamento.out -time -node $IDnode -dof $IDdir disp;
recorder Element -file Forza.out -ele 1 force
# recorder Node -file Forza.out -node 4 -dof 1 reaction;

set Lambda [eigen -fullGenLapack $nEig]
puts "\nEigenvalues at start of transient:"
puts "Lambda\t Omega\t Period" ;# Neat-looking header
foreach Lambda $Lambda {
if {$Lambda > 0.0} {
set Omega [expr {pow($Lambda,0.5)}]
set Period [expr 2*$PI/$Omega]
puts "$Lambda\t $Omega\t $Period"
}
}

#---------------------------------------------------------------------------------------
#GRAVITY LOADS
set N [expr -1.*$M*$g];
pattern Plain 4 Linear {
load 4 0. $N
}

set u_F [expr -$N*$mu1/$K]; #Soglia di spostamento finale
set u_C [expr 4*$u_F];
puts "Displacement reduction: $u_C"
puts "Displacement threshold: $u_F"

algorithm Linear
system BandSPD
pattern MultipleSupport 1 {
#groundMotion 1 Series -disp $dispSeries
groundMotion 1 Plain -disp $dispSeries
#imposedSupportMotion 2 1 1
imposedMotion 2 1 1
}


integrator LoadControl 1
numberer RCM
constraints Transformation;#Penalty 1e16 1e16
analysis Static
analyze 1

remove loadPattern 1

# Set up analysis parameters
source LibAnalysisDynamicParameters.tcl
set TmaxAnalysis [expr 1*[lindex $Data_input 4]]; # Maximum duration of ground-motion analysis
set DtAnalysis [expr $TmaxAnalysis/3000.]; # Time-step Dt for lateral analysis

rayleigh 0. 0. 0. 0.;

# integrator Newmark 0.5 0.25
# analysis Transient
# analyze 1000 0.01

set Tol 1.e-6
set Nsteps [expr int($TmaxAnalysis/$DtAnalysis)];
set ok [analyze $Nsteps $DtAnalysis]; # Actually perform analysis; returns ok=0 if analysis was successful

if {$ok != 0} { ; # Analysis was not successful.
# --------------------------------------------------------------------------------------------------
# Change some analysis parameters to achieve convergence
# Performance is slower inside this loop
# Time-controlled analysis
set ok 0;
set controlTime [getTime];
while {$controlTime < $TmaxAnalysis && $ok == 0} {
set controlTime [getTime]
set ok [analyze 1 $DtAnalysis]
if {$ok != 0} {
puts "Trying Newton with Initial Tangent .."
test NormDispIncr $Tol 1000 0
algorithm Newton -initial
set ok [analyze 1 $DtAnalysis]
test $testTypeDynamic $TolDynamic $maxNumIterDynamic 0
algorithm $algorithmTypeDynamic
}
if {$ok != 0} {
puts "Trying Broyden .."
algorithm Broyden 8
set ok [analyze 1 $DtAnalysis]
algorithm $algorithmTypeDynamic
}
if {$ok != 0} {
puts "Trying NewtonWithLineSearch .."
algorithm NewtonLineSearch .8
set ok [analyze 1 $DtAnalysis]
algorithm $algorithmTypeDynamic
}
}

}; # end if ok !0

Hi all,

I want to simulate the Coulomb friction between two nodes. Below you can find an example of 1DOF system with a initial displacement (1.5 m) and after that free vibration. Following theory ( see e.g. Chopra book) at each cycle the displacement should have a linear decrease, and finaly a permanent displacement when the peak is lower than (mu*N/k). In my case I don't have a linear decrease. Do you have some suggestions?

Thanks,
Andrea
*****************************************************************

wipe;
source Units.tcl
model basic -ndm 2 -ndf 2

set dispSeries "Linear -factor 1.50"

node 1 0.0 0.0
node 2 0.0 0.0

set M 1.0
mass 2 $M 0.0

set nEig 1
fix 1 1 1

set K 30.
uniaxialMaterial Elastic 1 $K

set matTag 1
set eleTag 1
set dirTag 1
element zeroLength $eleTag 1 2 -mat $matTag -dir $dirTag

#---------------------------------------------------------------------------------------
#CONTACT ELEMENT
model basic -ndm 2 -ndf 2;

node 3 0. 0.
node 4 0. 0.

equalDOF 1 3 1 2
equalDOF 2 4 1 2

set mu1 0.1
set normalX 0
set normalY 1
set Kn 1.0e+8
set Kt 1.0e+8;

element zeroLengthContact2D 2 4 3 $Kn $Kt $mu1 -normal $normalX $normalY
#---------------------------------------------------------------------------------------

set IDnode 2
set IDdir 1
recorder Node -file Spostamento.out -time -node $IDnode -dof $IDdir disp; #Relative quantity

set Lambda [eigen -fullGenLapack $nEig]
puts "\nEigenvalues at start of transient:"
puts "Lambda\t Omega\t Period" ;# Neat-looking header
foreach Lambda $Lambda {
if {$Lambda > 0.0} {
set Omega [expr {pow($Lambda,0.5)}]
set Period [expr 2*$PI/$Omega]
puts "$Lambda\t $Omega\t $Period"
}
}

#---------------------------------------------------------------------------------------
#GRAVITY LOADS
set N -15.;
pattern Plain 4 Linear {
load 4 0. $N
}

set u_F [expr -$N*$mu1/$K]
puts $u_F

algorithm Linear
system BandSPD
pattern MultipleSupport 1 {
#groundMotion 1 Series -disp $dispSeries
groundMotion 1 Plain -disp $dispSeries
#imposedSupportMotion 2 1 1
imposedMotion 2 1 1
}


integrator LoadControl 1
numberer RCM
constraints Penalty 1e16 1e16
analysis Static
analyze 1

remove loadPattern 1

# Set up analysis parameters
source LibAnalysisDynamicParameters.tcl
set TmaxAnalysis [expr 10. *$sec]; # Maximum duration of ground-motion analysis
set DtAnalysis [expr 0.001*$sec]; # Time-step Dt for lateral analysis

rayleigh 0.00 0. 0. 0.;

# integrator Newmark 0.5 0.25
# analysis Transient
# analyze 1000 0.01

set Tol 1.e-6
set Nsteps [expr int($TmaxAnalysis/$DtAnalysis)];
set ok [analyze $Nsteps $DtAnalysis]; # Actually perform analysis; returns ok=0 if analysis was successful

if {$ok != 0} { ; # Analysis was not successful.
# --------------------------------------------------------------------------------------------------
# Change some analysis parameters to achieve convergence
# Performance is slower inside this loop
# Time-controlled analysis
set ok 0;
set controlTime [getTime];
while {$controlTime < $TmaxAnalysis && $ok == 0} {
set controlTime [getTime]
set ok [analyze 1 $DtAnalysis]
if {$ok != 0} {
puts "Trying Newton with Initial Tangent .."
test NormDispIncr $Tol 1000 0
algorithm Newton -initial
set ok [analyze 1 $DtAnalysis]
test $testTypeDynamic $TolDynamic $maxNumIterDynamic 0
algorithm $algorithmTypeDynamic
}
if {$ok != 0} {
puts "Trying Broyden .."
algorithm Broyden 8
set ok [analyze 1 $DtAnalysis]
algorithm $algorithmTypeDynamic
}
if {$ok != 0} {
puts "Trying NewtonWithLineSearch .."
algorithm NewtonLineSearch .8
set ok [analyze 1 $DtAnalysis]
algorithm $algorithmTypeDynamic
}
}

}; # end if ok !0

Dear Frank,

i downloaded the latest version of OpenSeesSP 64 bit available on the website, and my operating system is windows 8.1 64 bit.

Thanks for the replay.

Andrea

Dear all,

i installed all the files to use a parallel processing but when i write mpiexec -np $n OpenSeesSP $filename no action occurs. Simply i go to the next line in the command window.

What is the problem?

Thanks in advance,
Andrea

Ok, I solved in this way:

set Quad quad
set thick 0.18
set mat 30

if {$Quad == "enhancedQuad" } {
set eleArgs "PlaneStress2D 1"
}
if {$Quad == "quad" } {
set eleArgs "$thick PlaneStress2D $mat"
}
if {$Quad == "bbarQuad" } {
set eleArgs "1"
}

set nx 16
set ny 4

set start 0.

set blockCmd "block2D $nx $ny 1 1 $Quad \"$eleArgs\" {
1 $start $start
2 40 0
3 40 10
4 0 10
}"
eval $blockCmd


Andrea

Why if I use this sintax:

set nx 16
set ny 4

set start 0.

block2D $nx $ny 1 1 $Quad $eleArgs {
1 $start $start
2 40 0
3 40 10
4 0 10
}

There is the following error:

WARNING block2D numX? numY? startNode? startEle? eleType? eleArgs? : invalid node coordinate for node: 1
expected floating-point number but got "$start"
while executing
"block2D $nx $ny 1 1 $Quad $eleArgs {
1 $start $start
2 40 0
3 40 10
4 0 10
}"


Actually $start is a floating number. Otherwise, if I write directly 1 0. 0. no error occur.

Thanks for your reply.

Andrea

Ok, I will wait the structural response.

Thanks,
Andrea

Thanks Dr. McKenna.

Andrea

Dear all,

i want to perform different nonlinear analyses on a frame structure with lots of cladding panels, so i need to perform an eigenvalue analysis. The masses are not distributed but simply concentrated on the top of the columns (5) but still the eigenvalue analysis is quite long. Is there a possibility to to speed up the process?

Thanks in advance.

Andrea

Hi all,

I want to model a precast building (in 2D) which includes beams, columns and cladding elements, for which i want to use quad elements and block2D command. However i have this error:

WARNING block2D numX? numY? startNode? startEle? eleType? eleArgs? : invalid number of node args: PlaneStress

while executing
"block2D 4 8 1 1 quad 0.16 PlaneStress 666 {
1 0.36 0. 0.
2 1.65 0. 0.
3 1.65 2.70 0.
4 0.36 2.70 0.

}"


The part of the code is this:

set PlateThick 0.16
set PlateMat 666
set fc 53; # Concrete nominal compressive strength (MPa)
set Ec [expr $MPa*22000*pow(($fc/10.),0.3)]; # Concrete Young's Modulus
set nu 0.2
set rho 0.
nDMaterial ElasticIsotropic $PlateMat $Ec $nu $rho

set Plate quad
set tipoA PlaneStress
set eleArgs "$PlateThick $tipoA $PlateMat"

set blockCmd "block2D $nx $ny 1 1 $Plate $eleArgs {
1 $Xinizio 0. 0.
2 [expr $Xinizio+$LengthPannelli] 0. 0.
3 [expr $Xinizio+$LengthPannelli] $Y2 0.
4 $Xinizio $Y2 0.

}"
eval $blockCmd



Could you please help me? Thanks a lot,
Andrea

Many thanks.

Andrea

I found that exec octave -r "FileName.m" does not work. Is there an equivalent command for Octave?

Thanks in advance