I want to get SDOF (Tn(natural frequency)=2.83) output.
So I used "rayleigh " command to get output.
First I used
set damp 0.61
set omega [expr sqrt($K/$m)]
rayleigh 0 0 0 [expr 2.*$damp/($omega)]
Second I used(https://opensees.berkeley.edu/wiki/inde ... ver_Column)
set damp 0.61
set freq [expr [eigen -fullGenLapack 1]**0.5]
rayleigh 0. 0. 0. [expr 2*$damp/$freq]
but outputs(deformation) were different.
What is correct?
(Otherthings are same,
ex. element and material)
Thanks for answering
command(except damping)
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# units: kg, mm, sec, N
wipe all
# Define Acc file
source model.tcl
set Accfile "$acc3.acc"
set outputfile "$output3_eq-non(8)"
set dt $dt_acc
set Nsteps $Nsteps_acc
# Define Save
file mkdir $outputfile
# Define model
model BasicBuilder -ndm 2 -ndf 3
set h 3500
set m 5.908
set g 9800
set W [expr $m*$g]
node 1 0.0 0.0
node 2 0.0 $h -mass $m 1e-9 0.0
fix 1 1 1 1
fix 2 0 1 1
set Tn 2.83; # sec (Natural period)
set pi [expr acos(-1.0)];
# Columns and Beam Properties
set K [expr pow(2*$pi/$Tn,2)*$m]; # KN/mm
set Fy 10000000
set E $K
set b 0
# Define Material
set materialTag 1
uniaxialMaterial Steel01 $materialTag $Fy $E $b
# Define Element
set elementTag 1
element twoNodeLink $elementTag 1 2 -mat $materialTag -dir 2 -doRayleigh;
puts "Model Built"
# Define timeSeries
#timeSeries Path $tag -dt $dt -filePath $filePath <-factor $cFactor>
#define acceleration vector from file (dt=0.01 is associated with the input file gm)
timeSeries Path 1001 -dt $dt -filePath $Accfile -factor $g;
# Define RECORDERS
recorder Node -file $outputfile/Aabs.out -timeSeries 1001 -time -node 2 -dof 1 accel;
recorder Node -file $outputfile/Afree.out -time -time -node 2 -dof 1 accel; # displacements of free nodes
recorder Element -file $outputfile/Deform.out -time -ele 1 deformations ;
recorder Element -file $outputfile/Force.out -time -ele 1 globalForce ;
# Define Damping
#set damping based on first eigen mode
#pattern UniformExcitation $patternTag $dir -accel $tsTag <-vel0 $ver0>
pattern UniformExcitation 1 1 -accel 1001; # define where and how (pattern tag, dof) acceleration is applied
# create the analysis
#wipeAnalysis; # clear previously-define analysis parameters
constraints Transformation; # how it handles boundary conditions
numberer Plain; # renumber dof's to minimize band-width (optimization), if you want to
system SparseGeneral -piv; # how to store and solve the system of equations in the analysis (large model: try UmfPack)
test EnergyIncr 1.0e-8 100 0; # test Eneregy incerment
algorithm ModifiedNewton; # use Kyrlow-Newton algorithm
integrator Newmark 0.5 0.25 ; # determine the next time step for an analysis
analysis Transient; # define type of analysis: time-dependent
analyze $Nsteps $dt; # apply 10*4096 steps for 0.001-sec time steps in analysis
wipe
puts "Done!"