Brick elements/ transient analysis

[sgs]

Dear all,
I have a problem using Brick elements in transient analysis. I modeled a simple model of 5 brick elements. I tried static, modal and transient analyses on this model. While the results of static, modal cases are exactly like sap2000 results, the results I am getting for transient analysis deviates from sap2000 (both using modal analysis and direct integration using newmark beta .5 .25!!).
Can anybody help me with this please?

Here is my code:
set dataDir Solid_element_Modal;
file mkdir $dataDir;
model BasicBuilder -ndm 3 -ndf 3
set E 12328.207
set v 0.200
set mass1 0.405
set mass2 0.809
set matTag 1
nDMaterial ElasticIsotropic $matTag $E $v
node 1 5.0 0.0 0.0 -mass $mass2 $mass2 $mass2
node 2 5.0 5.0 0.0 -mass $mass2 $mass2 $mass2
node 3 0.0 5.0 0.0 -mass $mass2 $mass2 $mass2
node 4 0.0 0.0 0.0 -mass $mass2 $mass2 $mass2
node 5 5.0 5.0 5.0 -mass $mass2 $mass2 $mass2
node 6 0.0 5.0 5.0 -mass $mass2 $mass2 $mass2
node 7 0.0 0.0 5.0 -mass $mass2 $mass2 $mass2
node 8 5.0 0.0 5.0 -mass $mass2 $mass2 $mass2
node 9 5.0 5.0 10.0 -mass $mass2 $mass2 $mass2
node 10 0.0 5.0 10.0 -mass $mass2 $mass2 $mass2
node 11 0.0 0.0 10.0 -mass $mass2 $mass2 $mass2
node 12 5.0 0.0 10.0 -mass $mass2 $mass2 $mass2
node 13 5.0 5.0 15.0 -mass $mass2 $mass2 $mass2
node 14 0.0 5.0 15.0 -mass $mass2 $mass2 $mass2
node 15 0.0 0.0 15.0 -mass $mass2 $mass2 $mass2
node 16 5.0 0.0 15.0 -mass $mass2 $mass2 $mass2
node 17 0.0 5.0 20.0 -mass $mass2 $mass2 $mass2
node 18 0.0 0.0 20.0 -mass $mass2 $mass2 $mass2
node 19 5.0 0.0 20.0 -mass $mass2 $mass2 $mass2
node 20 5.0 5.0 20.0 -mass $mass2 $mass2 $mass2
node 21 5.0 5.0 25.0 -mass $mass1 $mass1 $mass1
node 22 0.0 5.0 25.0 -mass $mass1 $mass1 $mass1
node 23 0.0 0.0 25.0 -mass $mass1 $mass1 $mass1
node 24 5.0 0.0 25.0 -mass $mass1 $mass1 $mass1
element SSPbrick 1 1 2 3 4 5 6 7 8 $matTag
element SSPbrick 2 5 6 7 8 9 10 11 12 $matTag
element SSPbrick 3 9 10 11 12 13 14 15 16 $matTag
element SSPbrick 4 13 14 15 16 17 18 19 20 $matTag
element SSPbrick 5 17 18 19 20 21 22 23 24 $matTag
fix 1 1 1 1
fix 2 1 1 1
fix 3 1 1 1
fix 4 1 1 1
puts "Model Built"
set accelSeries "Series -dt 0.005 -filePath GM.acc -factor 386.4 "
pattern UniformExcitation 1 1 -accel $accelSeries
puts "Model Built"
recorder Node -file $dataDir/DISPLx.out -nodeRange 1 24 -dof 1 disp
recorder Node -file $dataDir/DISPLy.out -nodeRange 1 24 -dof 2 disp
recorder Element -eleRange 1 24 -time -file $dataDir/stress.out stress
numberer Plain
constraints Plain
system BandGeneral
integrator Newmark 0.5 0.25
test EnergyIncr 1.0e-6 10
algorithm Newton
analysis Transient
analyze 16384 0.005


Thanks,