stability on ida analysis

[majidkhan]

dear silvia and fmk i modeled one story frame with steel material and do ida analysis, but when i increase specturum acclearation to 2g or 3g or more frame is stable, please help what is wrong? thank you , my script is :

for {set i 1} {$i<=30} {incr i 1} {
file mkdir data/[expr $i./10]sa
wipe

model basic -ndm 3 -ndf 6

file mkdir data

node 1 0. 0. 0.
node 2 3. 0. 0.
node 3 0. 3. 0.
node 4 3. 3. 0.
node 5 0. 0. 3.
node 6 3. 0. 3.
node 7 0. 3. 3.
node 8 3. 3. 3.

fixZ 0.0 1 1 1 1 1 1

#Assigning Rigid Diaphragm
node 9 1.5 1.5 3.
fix 9 0 0 1 1 1 0
rigidDiaphragm 3 9 5 6 7 8

#Assigning Floor Mass to Center of the Mass of the story.
mass 9 4000. 4000. 0. 0. 0. [expr (1./12)*4000.*(pow(3,2)+pow(3,2))]


set ColumnTransfTag 1
geomTransf Linear $ColumnTransfTag 0 1 0

set BeamTransfTag 2
geomTransf Linear $BeamTransfTag 0 -1 0

set GirderTransfTag 3
geomTransf Linear $GirderTransfTag 1 0 0


uniaxialMaterial Steel01 1 2.354e8 2.e11 0.02

section fiberSec 1 {
patch quad 1 8 3 0.0915 0.05 0.0915 -0.05 0.1 -0.05 0.1 0.05
patch quad 1 3 8 -0.0915 0.0028 -0.0915 -0.0028 0.0915 -0.0028 0.0915 0.0028
patch quad 1 8 3 -0.1 0.05 -0.1 -0.05 -0.0915 -0.05 -0.0915 0.05
}

set e 2.e11
set nu 0.3
set G [expr $e/(2.*(1+$nu))]
set j 6.920e-8
set Tmattag 2
uniaxialMaterial Elastic $Tmattag [expr $G*$j]
section Aggregator 3 $Tmattag T -section 1



#Columns
element nonlinearBeamColumn 1 1 5 10 3 $ColumnTransfTag
element nonlinearBeamColumn 2 2 6 10 3 $ColumnTransfTag
element nonlinearBeamColumn 3 3 7 10 3 $ColumnTransfTag
element nonlinearBeamColumn 4 4 8 10 3 $ColumnTransfTag


#Beams
element nonlinearBeamColumn 5 5 6 10 3 $BeamTransfTag
element nonlinearBeamColumn 6 7 8 10 3 $BeamTransfTag

#Girders
element nonlinearBeamColumn 7 5 7 10 3 $GirderTransfTag
element nonlinearBeamColumn 8 6 8 10 3 $GirderTransfTag

set DeadLoad 1

pattern Plain $DeadLoad Linear {
eleLoad -ele 5 6 7 8 -type -beamUniform -5000 0.
}

puts "first mode w^2:[eigen 1]
first period:[expr 2*3.14/pow([eigen 1],0.5)]"

constraints Lagrange
numberer Plain
system BandGeneral
test EnergyIncr 1.e-8 6
algorithm ModifiedNewton
integrator LoadControl 0.01
analysis Static
analyze 100
loadConst -time 0.0

recorder display frame 1000 0 500 500 -wipe
vup 0 0 1 # dirn defining up direction of view plane(ghab bordar movazi)
vpn 0.7 1 0.3 # direction of outward normal to view plane(amud bar safhe ghab)
prp 1 1 0 # eye location in local coord sys defined by viewing system
viewWindow -5 5 -5 5
projection 1
display 1 5 4
recorder Drift -file data/[expr $i./10]sa/sa[expr $i./10]drift.out -time -iNode 1 -jNode 5 -dof 1 -perpDirn 3
set accel "Series -dt 0.02 -filePath tabas.txt -factor [expr $i.*9.81*0.617/10]"
pattern UniformExcitation 3 1 -accel $accel

puts "groundmotion start!.Time: [getTime]"
set dt 0.02
constraints Transformation
numberer Plain
system BandGeneral
test NormDispIncr 1.0e-8 10
algorithm Newton
integrator Newmark 0.5 0.25
analysis Transient
analyze [expr int(32.82/$dt)] $dt
puts "groundmotion [expr $i./10]sa done!.End Time: [getTime]"
}

[fmk]

one error you have, you want /10. and not /10 in accel definition, integer math will results in same factor for values used

set accel "Series -dt 0.02 -filePath tabas.txt -factor [expr $i.*9.81*0.617/10.]"