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thanks a lot for your response. But, my main objective is modelling liquefaction in partially saturated sands. Which model and element would be most appropriate for this issue? If there is not any, how we can modify available models to achieve the partial saturation state?

Hi,
Would you please let me know if there is any model and element for partially saturated sands? I mean, is there any code that user can change degree of saturation?
Thanks

Hi
Would you please let me know if there is any code for liquefaction modeling in a sand layer?

Dear Silvia
Hi
I have used your command for generating Moment-Curvature relationship under cyclic loads for column sections. Do you have any idea about getting its stress-strain relationship in OpenSees? It would be appreciated if you help me with this...

Dear Vesna
Hi
I tried the command you have put for moment-curvature analysis of section -- cyclic. I have 2 questions. Would you please help me with them?
1) In unloading phase, the curve becomes linear. What can be the main reason?
2) How can I get hysteretic loops for moment-curvature? The command in the forum gives only one loop.

Mohsen

Hi dear vesna...

I did pushover analysis for my 3D model.In first few modes I got the results,but in 7th mode I have a problem.(my model is SAC9 with 27 modes).

WARNING:CTestNormDispIncr::test<>-failed to converge.

What is wrong with this model?

Hi dear vesna...
I'd asked you a question about my model which has a rotational spring.The subject of that question was "rotational springs".
As you advised me,I applied another ground motion to my model and changed Fy,b.
Again,I found out that the results aren't being changed by changing Fy,b.
As you know,a rotational spring has some parameters for inelastic range: My(yielding moment) and K'(post-yielding stiffness of rotational spring).
Could you please show me a command which clearly helps me defining a rotational spring with above mentioned parameters?
Thanks a lot.
Mohsen

Hi dear vesna...
I applied another earthquake record to my model.It gets to the inelastic range,but my problem isn't solved.
I was wondering if you'd mind showing me a command which defines a rotational spring with its appropriate elastic and inelastic parameters.
As you know,a rotational spring needs some variables (My:yielding moment,as an inelastic parameter & post-yielding stiffness)to behave as a nonlinear element.
Please help me...
Thanks a lot.

Mohsen

Hi...

This is my commands for defining a 2 degree of freedom system:

# Set up---------------------------------------------------
wipe; # clear memory of all past model definitions
set dataDir Data; # set up name of data directory
file mkdir $dataDir; # create data directory
set GMdir "../GMfiles/"; #ground motion file directory

puts "set up"

#Define units------------------------------------------
set m 1;
set kg 1;
set sec 1;
set sec2 [expr $sec*$sec];
set m2 [expr $m*$m];
set pi [expr 2*asin(1.0)];
set g [expr 9.81*$m/$sec2];
set ubig 1e10;
set usmall [expr 1/$ubig];

puts "units are defined"

#units metric kg sec
#creat modelbuilder ( 3 dimensional and 6 degree of freedom for each node)----------
model basic -ndm 3 -ndf 6


#Define nodes------------------------------------------
node 1 0 0 0
node 2 0 0 0
node 3 -0.35 0 0



puts "nodes are defined"



#DEFINING MATERIALS-------------------------

# FOR SPRINGS
# uniaxialMaterial Steel01 $matTag $Fy $E0 $b

uniaxialMaterial Steel01 1 11 8.82 0.5 #(translational spring)
uniaxialMaterial Steel01 2 19 2.34 0.28 #(rotational spring)

puts "materials are defined"


#-------------------------------------------
geomTransf Linear 1 0 0 1

puts "geomTransf are defined"


#creating command named Rotational Springs -------------------------
# Create the zero length element
#element zeroLength $eleTag $iNode $jNode -mat $matTag1 $matTag2 ... -dir $dir1 $dir2 ...

element zeroLength 11 1 2 -mat 1 2 -dir 3 5


equalDOF 1 2 1 2 4 6

puts "sections are defined"


#element elasticBeamColumn $eleTag $iNode $jNode $A $E $G $J $Iy $Iz $transfTag-----------------------
#### beam(rigid)

element elasticBeamColumn 111 2 3 .1 10e10 10e10 .1 .1 .1 1

puts "elements are defined"


#----------------------------------------
fix 3 0 1 0 1 0 1

puts "center of mass is defined"


#Define mass--------------------------------------

set mass1 0.9471 #(mass)
set mass_I 0.0529 #(moment of inertia)

mass 3 $mass1 0 $mass1 0 $mass_I 0


puts "story mass are defined"


#Define restrain--------------------------------
fix 1 1 1 1 1 1 1

puts "support is defined"


#set recorders directions & adaresses----------

set mode1 "Data/Nodes Eigen vector mode1.txt"

set nodesdisplacement "Data/nodes displacement - 3.txt"

set envelopenodesdisplacement "Data/envelope nodes displacement - 3.txt"

###################################################################################################

#set recorders command----------

recorder Node -file $mode1 -time -node 3 -dof 3 "eigen 1"

recorder Node -file $nodesdisplacement -time -nodes 3 -dof 3 disp

recorder EnvelopeNode -file $envelopenodesdisplacement -time -node 3 -dof 3 disp

puts "recorder 2DOF"



#define gravity,weights----------

set Weight1 [expr $mass1*$kg*$g]


#define gravity loads-----------

pattern Plain 1 Linear {

load 3 0.0 -$Weight1 0.0 0.0 0.0 0.0

}

eigen 1

#Gravity analysis parameters--------LoadControl static analysis

set Tol 1.0e-8;
constraints Transformation;
numberer RCM;
system SparseGeneral;
test NormDispIncr $Tol 50;
algorithm Newton;
integrator LoadControl 0.1; #first load increment (pseudo-time step) in the next invocation of the analysis command.
analysis Static;
analyze 10;
loadConst -time 0.0; #keep gravity load and restart time -- lead to lateral load analysis

puts "define gravity loads & analysis"

set Lambda [eigen 1]
puts "\nEigenvalues at start of transient:"
puts " Lambda Omega Period"
foreach Lambda $Lambda {
if {$Lambda > 0.0} {
set Omega [expr pow($Lambda,0.5)]
set Period [expr 2*$pi/$Omega]
puts "-------------------------------------------"
puts "$Lambda $Omega $Period"
}
}


# define dynamic analysis parameter------------------------------------

constraints Transformation
numberer RCM
system SparseGeneral
test NormDispIncr $Tol 50 0
algorithm Newton
integrator Newmark 0.5 0.25
analysis Transient

puts " "
puts "dynamic analysis parameter"


proc ReadSMDFile {inFilename outFilename dt} {
#########################################################
# ReadSMDFile $inFilename $outFilename $dt

# NPTS= 1642, DT= .02000 SEC

upvar $dt DT; # Pass dt by reference

# Open the input file and catch the error if it can't be read
if [catch {open $inFilename r} inFileID] {
puts stderr "Cannot open $inFilename for reading"
} else {
# Open output file for writing
set outFileID [open $outFilename w]

# Flag indicating dt is found and that ground motion
# values should be read -- ASSUMES dt is on last line
# of header!!!
set flag 0
# Look at each line in the file
foreach line [split [read $inFileID] \n] {
if {[llength $line] == 0} {
# Blank line --> do nothing
continue
} elseif {$flag == 1} {
# Echo ground motion values to output file
puts $outFileID $line
} else {
# Search header lines for dt
foreach word [split $line] {
# Read in the time step
if {$flag == 1} {
set DT $word
break
}
# Find the desired token and set the flag
if {[string match $word "DT="] == 1} {set flag 1}
}
}
}
close $outFileID; # Close the output file
close $inFileID; # Close the input file
}
}

puts "Proc ReadSMDFile"


# Uniform Earthquake ground motion (uniform acceleration input at all support nodes)
set GMdirection 3; # ground-motion direction
set GMfile "tabas.acc" ; # ground-motion filenames
set GMfact 1; # ground-motion scaling factor

# set up ground-motion-analysis parameters
set DtAnalysis [expr 0.02*$sec]; # time-step Dt for lateral analysis
set TmaxAnalysis [expr 30*$sec]; # maximum duration of ground-motion analysis -- should be 50*$sec

# ------------ define & apply damping
# RAYLEIGH damping parameters, Where to put M/K-prop damping, switches (http://opensees.berkeley.edu/OpenSees/m ... l/1099.htm)
# D=$alphaM*M + $betaKcurr*Kcurrent + $betaKcomm*KlastCommit + $beatKinit*$Kinitial
set xDamp 0.05; # damping ratio
set MpropSwitch 1.0;
set KcurrSwitch 0.0;
set KcommSwitch 1.0;
set KinitSwitch 0.0;
set nEigenI 1; # mode 1
set nEigenJ 1; # mode 1
set lambdaN [eigen [expr $nEigenJ]]; # eigenvalue analysis for nEigenJ modes
set lambdaI [lindex $lambdaN [expr $nEigenI-1]]; # eigenvalue mode i
set lambdaJ [lindex $lambdaN [expr $nEigenJ-1]]; # eigenvalue mode j
set omegaI [expr pow($lambdaI,0.5)];
set omegaJ [expr pow($lambdaJ,0.5)];
set alphaM [expr $MpropSwitch*$xDamp*(2*$omegaI*$omegaJ)/($omegaI+$omegaJ)]; # M-prop. damping; D = alphaM*M
set betaKcurr [expr $KcurrSwitch*2.*$xDamp/($omegaI+$omegaJ)]; # current-K; +beatKcurr*KCurrent
set betaKcomm [expr $KcommSwitch*2.*$xDamp/($omegaI+$omegaJ)]; # last-committed K; +betaKcomm*KlastCommitt
set betaKinit [expr $KinitSwitch*2.*$xDamp/($omegaI+$omegaJ)]; # initial-K; +beatKinit*Kini
rayleigh $alphaM $betaKcurr $betaKinit $betaKcomm; # RAYLEIGH damping

# --------------------------------- perform Dynamic Ground-Motion Analysis
# the following commands are unique to the Uniform Earthquake excitation
set IDloadTag 400; # for uniformSupport excitation

# Uniform EXCITATION: acceleration input
set inFile tabas.acc;
set outFile tabas.th; # set variable holding new filename (PEER files have .at2/dt2 extension)
ReadSMDFile $inFile $outFile dt; # call procedure to convert the ground-motion file
set GMfatt [expr $g*$GMfact]; # data in input file is in g Unifts -- ACCELERATION TH
set AccelSeries "Series -dt $dt -filePath $outFile -factor $GMfatt"; # time series information
pattern UniformExcitation $IDloadTag $GMdirection -accel $AccelSeries ; # create Unifform excitation

set Nsteps [expr int($TmaxAnalysis/$DtAnalysis)];

set ok 0;
set controlTime [getTime];
set nModes 1
set i 0
for {set i 0} {$i<$Nsteps} {incr i 1} {
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

}

if {$ok == 0} {
eigen $nModes
}
}


}
puts "Ground Motion Done. End Time: [getTime]"



Thanks a lot dear vesna.
I'm preparing my thesis,and your advices are very useful for me.

Hi dear vesna...

I have defined a rotational spring by this command:(I have put appropriate values instead of each $)

uniaxialMaterial Steel01 $matTag $Fy $E0 $b
element zeroLength $eleTag $iNode $jNode -mat $matTag1 $matTag2 ... -dir $dir1 $dir2 ...
equalDOF $nodeR $nodeC ...

I applied a ground motion to my model and got results.My problem is that when I change $E0,results are being changed but when I change $Fy or $b,the results aren't being changed.It seems that this rotational spring is considered as an elastic element.
Please help me how I can enter inelastic parameters of spring in command?
thanks a lot...

Mohsen.

Hi dear vesna...

I have 2 questions:

1)Is rigidLink command useful for defining rigid column and rigid beam?
2)I want to get the translational and rotational frequency of the structure.This is my primary command(for example) :
.
.
.
.
mass 1 0.1 0.1 1000 0.1 120000 0.1

If I define this command: mass 1 0.1 0.1 1000 0.1 0 0.1 ;and use the gravity analysis,Can I get the translational frequency?

thanks a lot for your help.

Hi dear...

Is there any difference between 2D & 3D problems in the rotational springs modelling?If yes,:

1)Which command helps me define a rotational spring in 3D problem?
My model has 2 rotational spring.One of them belongs to -dir5 and the other to -dir6

2)By which command,I can apply the rotational stiffness to the spring?

Thanks a lot for your help.

Hi dear vesna...

I want to get the base torque of structure.I've used this command:

set basetorque "Data/base torque -node 1 2 3 4.txt"
recorder Node -file $basetorque -time -node 1 2 3 4 -dof 5 reaction

opensees output is:

for example: -100 -200 -200 -100

so,the base torque=-100-200-200-100=-600

is it correct?

thanks alot...

Hi dear vesna
I defined a stucture in opensees
is there any command which can help me find the modal parameters?
for example : modal mass matrix and modal stiffness matrix of the entire structure?
thanks alot

I want to get the rotation of the floor
is it be ok if I use this command ?: recorder Node -file $node rotation -time -nodes 1 -dof 5 disp
where tag 1 belongs to CM(center of mass) of the floor.
thanks alot