gravity loads for static analysis

[ams]

Hi
pleas help me dear users
i made a 2d steel frame model in opensees and now i want to start static analysis after loading a gravity loads. but there is not any difference between periods before and after gravity loads ! ! how should i INTRODUCTION gravity loads.
i use this order for loading like this:
pattern plain 1 linear {
load 0.0 -4500. 0.0
.
.
this is my model where is my mistake
wipe

file mkdir eigenload
set txt [open eigenload/eigenload.out w+]

model basic -ndm 2 -ndf 3

node 1 0. 0.
node 2 4. 0.
node 3 8. 0.
node 4 12. 0.
node 5 0. 3.2
node 6 4. 3.2
node 7 8. 3.2
node 8 12. 3.2
node 9 0. 6.4
node 10 4. 6.4
node 11 8. 6.4
node 12 12. 6.4
node 13 0. 9.6
node 14 4. 9.6
node 15 8. 9.6
node 16 12. 9.6
###################
fix 1 1 1 1
fix 2 1 1 1
fix 3 1 1 1
fix 4 1 1 1
#######################
mass 13 586.4909611 1.e-8 1.e-8

mass 14 1172.981922 1.e-8 1.e-8

mass 15 1172.981922 1.e-8 1.e-8

mass 16 586.4909611 1.e-8 1.e-8

mass 9 583.6621667 1.e-8 1.e-8

mass 10 1167.324333 1.e-8 1.e-8

mass 11 1167.324333 1.e-8 1.e-8

mass 12 583.6621667 1.e-8 1.e-8

mass 5 587.9454667 1.e-8 1.e-8

mass 6 1175.890933 1.e-8 1.e-8

mass 7 1175.890933 1.e-8 1.e-8

mass 8 587.9454667 1.e-8 1.e-8
########################################
equalDOF 13 14 1
equalDOF 13 15 1
equalDOF 13 16 1
equalDOF 9 10 1
equalDOF 9 11 1
equalDOF 9 12 1
equalDOF 5 6 1
equalDOF 5 7 1
equalDOF 5 8 1

########################################

geomTransf PDelta 1


uniaxialMaterial Steel02 1 2.4e7 2.1e10 0.02
###############################################
source boxsection.tcl

#COLUMN SECTION

# 25x1.2
set D 0.25
set B 0.25
set T 0.012
set nfTl 10
set nfTt 2
set nfSl 10
set nfSt 2
BoxSection 1 1 0.25 0.25 0.012 10 2 10 2



# 25x1
set D 0.25
set B 0.25
set T 0.01
set nfTl 10
set nfTt 2
set nfSl 10
set nfSt 2

BoxSection 2 1 0.25 0.25 0.01 10 2 10 2



# 20x1.5
set D 0.2
set B 0.2
set T 0.015
set nfTl 10
set nfTt 2
set nfSl 10
set nfSt 2
BoxSection 3 1 0.2 0.2 0.015 10 2 10 2


#20x1
set D 0.2
set B 0.2
set T 0.01
set nfTl 10
set nfTt 2
set nfSl 10
set nfSt 2

BoxSection 4 1 0.2 0.2 0.01 10 2 10 2


# 20x0.8
set D 0.2
set B 0.2
set T 0.008
set nfTl 10
set nfTt 2
set nfSl 10
set nfSt 2
BoxSection 5 1 0.2 0.2 0.008 10 2 10 2

#15x1.2
set D 0.15
set B 0.15
set T 0.012
set nfTl 10
set nfTt 2
set nfSl 10
set nfSt 2
BoxSection 6 1 0.2 0.2 0.008 10 2 10 2

###########################################
#BEAM SECTIONS

source WSection.tcl

#pg4
set d 0.28
set bf 0.14
set tf 0.01
set tw 0.01
set nfdw 10
set nftw 2
set nfbf 10
set nftf 2


WSection 7 1 0.28 0.135 0.01 0.01 10 2 10 2


#pg5
set d 0.29
set bf 0.135
set tf 0.012
set tw 0.008
set nfdw 10
set nftw 2
set nfbf 10
set nftf 2
WSection 8 1 0.34 0.3 0.0215 0.012 10 2 10 2

#IPE220
set d 0.22
set bf 0.11
set tf 0.0092
set tw 0.0059
set nfdw 10
set nftw 2
set nfbf 10
set nftf 2

WSection 9 1 0.22 0.11 0.0092 0.0059 10 2 10 2

element nonlinearBeamColumn 1 1 5 8 2 1
element nonlinearBeamColumn 2 2 6 8 1 1
element nonlinearBeamColumn 3 3 7 8 1 1
element nonlinearBeamColumn 4 4 8 8 2 1

element nonlinearBeamColumn 5 5 6 8 8 1
element nonlinearBeamColumn 6 6 7 8 8 1
element nonlinearBeamColumn 7 7 8 8 8 1

element nonlinearBeamColumn 8 5 9 8 4 1
element nonlinearBeamColumn 9 6 10 8 3 1
element nonlinearBeamColumn 10 7 11 8 3 1
element nonlinearBeamColumn 11 8 12 8 4 1

element nonlinearBeamColumn 12 9 10 8 7 1
element nonlinearBeamColumn 13 10 11 8 7 1
element nonlinearBeamColumn 14 11 12 8 7 1

element nonlinearBeamColumn 15 9 13 8 6 1
element nonlinearBeamColumn 16 10 14 8 5 1
element nonlinearBeamColumn 17 11 15 8 5 1
element nonlinearBeamColumn 18 12 16 8 6 1

element nonlinearBeamColumn 19 13 14 8 9 1
element nonlinearBeamColumn 20 14 15 8 9 1
element nonlinearBeamColumn 21 15 16 8 9 1

pattern Plain 1 Linear {


load 13 0. -5753.476329 0.
load 14 0. -11506.95266 0.
load 15 0. -11506.95266 0.
load 16 0. -5753.476329 0.
load 9 0. -5725.725855 0.
load 10 0. -11451.45171 0.
load 11 0. -11451.45171 0.
load 12 0. -5725.725855 0.
load 5 0. -5767.745028 0.
load 6 0. -11535.49006 0.
load 7 0. -11535.49006 0.
load 8 0. -5767.745028 0.
}


set Pi [expr 4*atan(1)]

set eig [eigen 3]

puts $txt "Eigen Values are: $eig"
puts $txt "First Mode Period is:[expr 2*3.1415/pow([lindex $eig 0],0.5)]"
puts $txt "Second Mode Period is:[expr 2*3.1415/pow([lindex $eig 1],0.5)]"
puts $txt "third Mode Period is:[expr 2*3.1415/pow([lindex $eig 2],0.5)]"

[fmk]

what exactly is the question .. the period of the structure will not change until the materials start yielding.

[ams]

thanks for your attention Mr
i could find my answer