problem description
title="3d Beam Sample Problem (Logan #6.43, p.266)" nodes=3 elements=2 

nodes
1 x=0 y=0 z=0 constraint=fixed
2 x=120 y=0 z=0 constraint=free force=point_load
3 x=120 y=0 z=-120 constraint=fixed

beam3d elements
1 nodes=[1,2] material=steel
2 nodes=[2,3] material=steel

material properties
steel e=30e6 g=12e6 iy=200 iz=200 a=10 j=100

forces
point_load fy=-5000 

constraints
fixed tx=c ty=c tz=c rx=c ry=c rz=c
free tx=u ty=u  tz=u rz=u rx=u ry=u rz=u

end
