problem description
title="htk sample"
nodes=9 elements=4 analysis=modal

analysis parameters
mass-mode=lumped

nodes
1  x=0 y=0 z=0 constraint=clamp
2  x=0.5 y=0 z=0
3  x=0.5 y=0.5 z=0
4  x=0 y=0.5 z=0
5  x=0.25 y=0 z=0
6  x=0 y=0.25 z=0	
7  x=0.25 y=0.25 z=0	constraint=free
8  x=0.5 y=0.25 z=0	constraint=clamp
9  x=0.25 y=0.5 z=0

htk elements
1  nodes=[1,5,7,6] material=steel
2  nodes=[5,2,8,7]
3  nodes=[6,7,9,4]
4  nodes=[7,8,3,9]

material properties
steel E=1.173e+07 nu=0.15 t=0.01 rho=5

constraints
clamp Tx=u Ty=u Tz=c Rx=c Ry=c Rz=u
free  Rx=c Ry=c

end