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Hello
How to build a single dof system which considers deterioration with the ability to change its ductility.
I would really appreciate it if the commands are proposed.
Thanks for your attention

Hi.
My problem is about Steel01 four isotropic parameters. I want to know how these four parameters are used to make stress-strain diagram. How do they effect pressure and tension? I took a look at the some examples and arguments in OpenSees wiki figures but I could not find the exact equation for these parameters and stress strain relationship. Actually I saw that by increasing some parameters pressure goes up or down but I want to know this more by detail and equations.

Hi.
thanks for your previous attention but my problem is still about yield point in spite of the reasonable ductility.
I would appreciate it if you could help me.
Actually I want to study different uniaxial materials behaviours and their strain stress diagrams. So I tried to made a simple model as a simple truss with a cyclic load to study the displacements and forces in order to have stress and strain diagram. At first I tried elastic material with no problem, but when I changed the material to "Elastic perfectly plastic" by "ElasticPP" command my simple file does not converge a bout given yield point.
It's about five weeks that I have been trying to solve this problem but unfortunately I have not been successful.
It is good to mention that I tried to consider the reasonable ductility as : .0001*20=0.002 m=0.2 cm------ 0.2/.1=2

There is my file in the following:

# units: N, m
wipe
# Create ModelBuilder (with two-dimensions and 2 DOF/node)
model BasicBuilder -ndm 2 -ndf 3
# Create nodes & add to Domain - command: node nodeId xCrd yCrd
node 1 0. 0.
node 2 1. 0.
# Set the boundary conditions - command: fix nodeID xResrnt? yRestrnt?
fix 1 0 1 1
fix 2 1 1 1
# Define materials for truss elements
uniaxialMaterial ElasticPP 1 200000. 0.001
# Create truss elements - command: element truss trussID node1 node2 A matID
element corotTruss 1 1 2 1 1

pattern Plain 2 Linear {
# Create the nodal load - command: load nodeID xForce yForce
load 1 1.0 0. 0.
}

# create a Recorder object for the nodal displacements at node 1
recorder Node -file disp1.out -time -node 1 -dof 1 disp
recorder Node -file reac2.out -time -node 2 -dof 1 reaction
# create a Recorder for element forces, one for global system and the other for local system
recorder Element -file eleGlobal.out -time -ele 1 localforces
recorder Element -file eleLocal.out -time -ele 1 basicForces

# Create the constraint handler, a Plain handler is used as homo constraints
constraints Plain
# Create the DOF numberer, the reverse Cuthill-McKee algorithm
numberer Plain
test EnergyIncr 1.0e-6 150
system BandGeneral

algorithm ModifiedNewton

set j 0.0001
for {set i 1} {$i<=40} {incr i 1} {
set j [expr -1.00*$j]
integrator DisplacementControl 1 1 $j
# create the analysis object
analysis Static
set ok [ analyze 20]

puts $i
}
puts "node 1 displacement: [nodeDisp 1]"
print node 1
print element

what about this one?
it seems reasonable but still with problem about yield point:

# units: N, m
wipe
# Create ModelBuilder (with two-dimensions and 2 DOF/node)
model BasicBuilder -ndm 2 -ndf 3
node 1 0. 0.
node 2 1. 0.

fix 1 0 1 1
fix 2 1 1 1
# Define materials for truss elements
uniaxialMaterial ElasticPP 1 200000. 0.001

element corotTruss 1 1 2 1 1
# Define loads
# create a Linear TimeSeries with a tag of 1
# Create a Plain load pattern associated with the TimeSeries,
# command: pattern Plain $patternTag $timeSeriesTag { load commands }

pattern Plain 2 Linear {
# Create the nodal load - command: load nodeID xForce yForce
load 1 1.0 0. 0.
}

# create a Recorder object for the nodal displacements at node 1
recorder Node -file disp1.out -time -node 1 -dof 1 disp
recorder Node -file reac2.out -time -node 2 -dof 1 reaction

# create a Recorder for element forces, one for global system and the other for local system
recorder Element -file eleGlobal.out -time -ele 1 localforces
recorder Element -file eleLocal.out -time -ele 1 basicForces

# Create the constraint handler, a Plain handler is used as homo constraints
constraints Plain

# Create the DOF numberer, the reverse Cuthill-McKee algorithm
numberer Plain

test EnergyIncr 1.0e-6 150
# Create the system of equation# systeme hale moadelat ra miguyad
system BandGeneral

# Create the solution algorithm, a Linear algorithm is created
algorithm ModifiedNewton

set j 0.0001
for {set i 1} {$i<=40} {incr i 1} {
set j [expr -1*$j]
integrator DisplacementControl 1 1 $j
# # create the analysis object
analysis Static
set ok [ analyze 20]

puts $i
}

puts "node 1 displacement: [nodeDisp 1]"
print node 1
print element

I have a problem in my file that I can not find. this happens near yield strain point.
help me please. I am really in troubles.


# units: N, m
# Remove existing model
wipe
# Create ModelBuilder (with two-dimensions and 2 DOF/node)
model BasicBuilder -ndm 2 -ndf 3
# Create nodes
# ------------
# Create nodes & add to Domain - command: node nodeId xCrd yCrd
node 1 0. 0.
node 2 1. 0.
# Set the boundary conditions - command: fix nodeID xResrnt? yRestrnt?
fix 1 0 1 1
fix 2 1 1 1
# Define materials for truss elements
# -----------------------------------
# Create Elastic material prototype - command: uniaxialMaterial Elastic matID E


uniaxialMaterial ElasticPP 1 200000. 0.0012

# Define elements
# Create truss elements - command: element truss trussID node1 node2 A matID
element corotTruss 1 1 2 1 1


# Define loads
# ------------


pattern Plain 2 Linear {
# Create the nodal load - command: load nodeID xForce yForce
load 1 1.0 0. 0.
}


# Create a recorder to monitor nodal displacements

# create a Recorder object for the nodal displacements at node 1
recorder Node -file disp1.out -time -node 1 -dof 1 disp
recorder Node -file reac2.out -time -node 2 -dof 1 reaction


# create a Recorder for element forces, one for global system and the other for local system
recorder Element -file eleGlobal.out -time -ele 1 localforces
recorder Element -file eleLocal.out -time -ele 1 basicForces

# Create the constraint handler, a Plain handler is used as homo constraints

constraints Plain

# Create the DOF numberer, the reverse Cuthill-McKee algorithm
numberer Plain
# dasture azmune hamgerayee safhe 85,
test EnergyIncr 1.0e-6 150
# Create the system of equation# systeme hale moadelat ra miguyad
system BandGeneral

# Create the solution algorithm, a Linear algorithm is created
algorithm ModifiedNewton


set j 0.0002
for {set i 1} {$i<=40} {incr i 1} {
set j [expr -1*$j]
integrator DisplacementControl 1 1 $j
# # create the analysis object
analysis Static
set ok [ analyze 1500]

puts $i
}
#

puts "node 1 displacement: [nodeDisp 1]"
print node 1
print element

hi. sorry if I post here
actually i do not know where should i post my problem but my problem has the same error:
warning bandgenlinlapacksolver
and this is my file:
# units: N, m

# Remove existing model
wipe

# Create ModelBuilder (with two-dimensions and 2 DOF/node)
model BasicBuilder -ndm 2 -ndf3

# Create nodes
# ------------
# Create nodes & add to Domain - command: node nodeId xCrd yCrd
node 1 0.0 0.0
node 2 1.0 0.0

# Set the boundary conditions - command: fix nodeID xResrnt? yRestrnt?
fix 1 0 1 1
fix 2 1 1 1

# Define materials for truss elements
# -----------------------------------
# Create Elastic material prototype - command: uniaxialMaterial Elastic matID E
uniaxialMaterial ElasticPP 1 200000.0 0.0012

# create section for StressStrain diagram

section Uniaxial 1 1 P

# Define elements

# Create truss elements - command: element truss trussID node1 node2 A matID
element truss 1 1 2 1.0 1


# Define loads
# ------------
#

# create a Linear TimeSeries with a tag of 1
timeSeries Linear 1
# Create a Plain load pattern associated with the TimeSeries,
# command: pattern Plain $patternTag $timeSeriesTag { load commands }

pattern Plain 2 1 {
# Create the nodal load - command: load nodeID xForce yForce
load 1 1.0 0.0 0.0
}



# Create a recorder to monitor nodal displacements


# create a Recorder object for the nodal displacements at node 1
recorder Node -file disp1.out -time -node 1 -dof 1 disp




#recorder display force-didp 20 20 500 500

#recorder plot disp1.out time-didp 200 200 500 500 -columns 1 2






# create a Recorder for element forces, one for global system and the other for local system
recorder Element -file eleGlobal.out -time -ele 1 localforces
recorder Element -file eleLocal.out -time -ele 1 basicForces

# get StressStrain diagram
recorder Element -file ele1sec1StressStrain.out -time -ele 1 section 1 fiber .1 .1 stressStrain
# recorder Element -file ele1sec1StressStrain.out -time -ele 1 section 1 fiber x stressStrain
# recorder Element -file StressStrain.out -time ele 1 sec 1




## dasturate analys
# Create the constraint handler, a Plain handler is used as homo constraints
#constraints Plain
constraints Transformation

# Create the DOF numberer, the reverse Cuthill-McKee algorithm
numberer RCM
# dasture azmune hamgerayee safhe 85,
test NormDispIncr 1.0e-8 150
# Create the system of equation# systeme hale moadelat ra miguyad
#system BandSPD
system BandGeneral
#system SparseGeneral
#system SparseGeneral -piv
#system UmfPack
#system ProfileSPD


# Create the solution algorithm, a Linear algorithm is created
#algorithm Linear
algorithm Newton


set j 0.000002
for {set i 1} {$i<=40} {incr i 1} {
set j [expr -1*$j]
integrator DisplacementControl 1 1 $j
# create the analysis object
analysis Static
set ok [ analyze 1500]

puts $i
}



puts "node 1 displacement: [nodeDisp 1]"
print node 1
print element


recorder display DisShape 800 10 400 400 -wipe
vup 0 1 0
vpn 0 0 1
prp 2 1.5 10
display 1 5 100

I could not find where the problem is. I would be appreciate it if anybody can help me.