eigenvalues

[mehdi1995]

hi
I want to get eigenvalues in each step of the analysis,but in the output file all of the eigenvalues in each step of the analysis are all the same.whats the problem? what should I do?
[code]
analysis Transient
analyze 10 0.0001
[code]
result:
recorder is one node in one dof:

0.0001 4.75794e-006
0.0002 4.75794e-006
0.0003 4.75794e-006
0.0004 4.75794e-006
0.0005 4.75794e-006
0.0006 4.75794e-006
0.0007 4.75794e-006
0.0008 4.75794e-006
0.0009 4.75794e-006
0.001 4.75794e-006

[fmk]

you have to calculate the eigenvalues after each analysis step .. use a loop:

[code]
for {set i 0} {$i<$numStep} {incr i 1} {
analyze 1 0.0001
eigen $numMode
}
[/code]

[mehdi1995]

I changed my code with the loop but the result are again the same!!
[code]
# Analysis: eigenAnalysis
# +++++++++++++++++++++++

# Define analysis options
# -----------------------
source AnalysisOptn_5.tcl
# Define recorder(s)
# --------------------
set nModes 3
#Set up recorders for eigen vectors
for {set i 0} {$i<10} {incr i 1} {
set jjj 0
for {set jjj 0} {$jjj < $nModes} {incr jjj 1} {
recorder Node -file eigenVector[expr {$jjj}].tmp -node 1 -dof 1 "eigen [expr $jjj + 1]"
#recorder Node -xml eigenVector[expr {$jjj}].tmp -node 1 -dof 1 "eigen [expr $jjj + 1]"
}
set eigenvalues [eigen $nModes]
analyze 1 0.01
eigen $nModes
}
# Clean up
# --------
#Remove the recorders
remove recorders
#Create .eig file
set name Bridge10
set _fID [open $name.eig w]
#Open the temp files
for {set jjj 0} {$jjj < $nModes} {incr jjj 1} {
set _fIDt [open eigenVector[expr {$jjj}].tmp]
set tempPeriod [expr 2*3.1416/sqrt([lindex $eigenvalues $jjj])]
set tempValues [read -nonewline $_fIDt]
puts $tempPeriod;# $tempValues
puts $_fID "$tempPeriod $tempValues"
close $_fIDt
}
#Close the .eig File
close $_fID

[fmk]

well then you are staying in the elastic range or you have no loads applied for transient part or the change in load is minimal and not causing the structure to move or undergo anymore nonlinear deformation.