problem description
title="Thin Pin-Pin Beam" 
nodes=3 elements=2 analysis=static-substitution

analysis parameters
load-steps = 10     tolerance = 0.001     iterations = 50      relaxation = 1.0
start = -1.0        stop = -12.0           step = -1.0
input-node = 2      input-dof = Ty
nodes=[2]           dofs=[Ty]

nodes
1 x=0	y=0	constraint=pin
2 x=120 y=0	constraint=free
3 x=240	y=0	constraint=pin

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

material properties
steel E=10e6 A=0.785 Ix=0.05

constraints
pin    Tx=c Ty=c Rz=u
free   Tx=u Ty=u Rz=u

end
