Problem with ElastiMultiLinear material model

[sugandha]

Hi,

I am using ElasticMultiLinear model to define a model which is elastic and has a gap of 1mm. when i check results and find stiffness, I don't get correct stiffness(k=31585000). Following is my code, please let me know how can I change this. Thank you.

#Analysis of SDoF system subjected to El Centro EQ of 10/15/79
#Material Model:- Elastic with 1mm gap
wipe;
#user defined variables
set mass 2000;
set g 9.81;
#build model
model BasicBuilder -ndm 2 -ndf 3
node 1 0 0;
node 2 0 0;
fix 1 1 1 1;
fix 2 0 1 1;
mass 2 $mass 0 0;
#define material
uniaxialMaterial ElasticMultiLinear 1 -strain -1 -0.002 -0.001 0 0.001 0.002 0.003 1 -stress -31585000 -63170 -31585 0 0 31585 63170 31553415
#element connectivity
element zeroLength 1 1 2 -mat 1 -dir 1;
#define recorders
recorder Node -file GapSDoF/NodeDisp.out -time -node 2 -dof 1 disp
recorder Node -file GapSDoF/NodeVel.out -time -node 2 -dof 1 vel
recorder Node -file GapSDoF/NodeAccel.out -time -node 2 -dof 1 accel
recorder Element -file GapSDoF/EleForce.out -time -ele 1 force
#recorder plot GapSDoF/NodeDisp.out "Nodal Displacement" 10 10 1000 400 -columns 1 2
#recorder plot GapSDoF/NodeAccel.out "Nodal Acceleration" 10 10 1000 400 -columns 1 2
#define load
timeSeries Path 1 -dt 0.02 -filePath ElCentro.ACC;
pattern UniformExcitation 1 1 -accel 1;
#define analysis commands
constraints Plain;
numberer Plain;
system FullGeneral;
test NormDispIncr 1.0e-8 100;
algorithm Newton;
integrator Newmark 0.5 0.25;
analysis Transient;
set T 50.02;
set dt 0.001;
analyze 50020 $dt;

Sugandha