How to apply acceleration to a certain node

[xujin]

My model is as follow. I want apply acceleration to node 5 .But i don't kown my way is right or wrong.

wipe
model BasicBuilder -ndm 2 -ndf 3
set PI [expr 2.0*asin(1.0)]
#设置单位
set N 1.0
set m 1.0
set kg 1.0
set sec 1.0

set mm [expr $m*0.001]
set cm [expr $m*0.01]
set kN [expr $N*1000]
set Pa [expr $N/($m*$m)]
set kPa [expr $Pa*1000]
set MPa [expr $Pa*1e6]
set m2 [expr $m*$m]
set cm2 [expr $cm*$cm]
set mm2 [expr $mm*$mm]
set m4 [expr $m2*$m2]
set cm4 [expr $cm2*$cm2]
set mm4 [expr $mm2*$mm2]
set m3 [expr $m*$m*$m]
set m4 [expr $m2*$m2]
set p [expr $kg/$m3] ;# density
set a [expr $m/($sec*$sec)] ;#accelerated speed

set A [expr 130*$cm2]
set Iz [expr 4267*$cm4]
set E [expr 2100*$kN/$cm2]
set m [expr 0.0001067*$kN/$cm]


node 1 0 0
node 2 1.2 0
node 3 2.4 0
node 4 3.6 0
node 5 4.8 0

if { [file exists kangzhen] ==0} {
file mkdir kangzhen;
}

recorder Node -file kangzhen/disp_1.txt -time -node 1 -dof 2 disp

fix 1 1 1 1

mass 2 0 $m 0
mass 3 0 $m 0
mass 4 0 $m 0
mass 5 0 $m 0

geomTransf Linear 1
#element element elasticBeamColumn eleTag iNode jNode A E Iz transfTag <-mass massDens> <-cMass>
element elasticBeamColumn 1 1 2 $A $E $Iz 1
element elasticBeamColumn 2 2 3 $A $E $Iz 1
element elasticBeamColumn 3 3 4 $A $E $Iz 1
element elasticBeamColumn 4 4 5 $A $E $Iz 1


set ACC "Series -dt 0.0001 -filePath acc.txt -factor 1"
pattern MultiSupport 1 {
groundMotion 1 Plain -accel $ACC
imposedMotion 5 2 1
}
constraints Transformation
numberer RCM
system UmfPack
test EnergyIncr 1.0e-6 200
algorithm KrylovNewton
integrator Newmark 0.5 0.25
analysis Transient
analyze 3503 0.0001
puts "succeed"