problem in use remove element

[chenari]

I need to use remove element command in my project. I encountered problem in use remove element that explain in the following two example below.

############################################
example 1

wipe all
model basic -ndm 2 -ndf 3
file mkdir rem
node 1 0. 0.
node 2 0. 0.
fix 1 1 1 1
equalDOF 1 2 2 3
mass 2 11025. 0. 0
uniaxialMaterial Elastic 1 290000.
uniaxialMaterial Viscous 2 290. 1
element zeroLength 1 1 2 -mat 1 -dir 1
element zeroLength 2 1 2 -mat 2 -dir 1
recorder Node -file rem/node2disp.txt -time -node 2 -dof 1 disp

set accel "Series -dt 0.01 -filePath elcentro.txt -factor [expr 9.81]"
pattern UniformExcitation 2 1 -accel $accel

constraints Plain
numberer Plain
system BandGeneral
test EnergyIncr 1.e-8 8
algorithm Newton
integrator Newmark 0.5 0.25
analysis VariableTransient
analyze 4000 0.01

#######################################################################
example 2
wipe all

model basic -ndm 2 -ndf 3
file mkdir rem
node 1 0. 0.
node 2 0. 0.
fix 1 1 1 1
equalDOF 1 2 2 3
mass 2 11025. 0. 0
uniaxialMaterial Elastic 1 290000.
uniaxialMaterial Viscous 2 290. 1
recorder Node -file rem/node2disp.txt -time -node 2 -dof 1 disp

set accel "Series -dt 0.01 -filePath elcentro.txt -factor [expr 9.81]"
pattern UniformExcitation 2 1 -accel $accel

constraints Plain
numberer Plain
system BandGeneral
test EnergyIncr 1.e-8 8
algorithm Newton
integrator Newmark 0.5 0.25
analysis VariableTransient


for {set i 1} {$i<4000} {incr i} {
element zeroLength 1 1 2 -mat 1 -dir 1
element zeroLength 2 1 2 -mat 2 -dir 1
analyze 1 0.01
remove element 1
remove element 2
}

################################################################
the problem is that the response for node 2 is very different in the two example so that in the two example response for node 2 should be equal.

would you like for solution this problem what should I do???????????

[fmk]

when adding elements to a model during an analysis the elements always look to see if there is some initial dislacements at the nodes .. if there is, they always subtract these off the trial displacements during an analysis .. the reason for this is that the element when added does not want to be in a state of stress (unless some initial strains are prescribed in the materials)

not knowing why you would want to do what you are doing I cannot offer you a solution.

[chenari]

Dear fmk
best regards
i want to update parameter damping coefficient viscous material through dynamic analysis in my project. because updateparameter do not work for this problem i use remove element through dynamic analysis and again added with new parameter through analysis.
can you offer a solution for this problem.????

[fmk]

you need to use the parameter/updateparameter command instead .. while not avail in 2.4.5 for C of the ViscousMaterial , it is in 2.4.6 ( i just added it this morning .. take it you put that other post in) .. will be avail later today

[chenari]

Dear fmk
thank you