*Heading
 B21 Elements, Static Analysis
*Node
      1,           0.,           0.
      2,           1.,           0.
      3,          10.,           1.
      4,           2.,    0.1111111
      5,           3.,    0.2222222
      6,           4.,    0.3333333
      7,           5.,    0.4444444
      8,           6.,    0.5555556
      9,           7.,    0.6666667
     10,           8.,    0.7777778
     11,           9.,    0.8888889
*Element, type=B21
1, 1, 2
 2,  2,  4
 3,  4,  5
 4,  5,  6
 5,  6,  7
 6,  7,  8
 7,  8,  9
 8,  9, 10
 9, 10, 11
10, 11,  3
** Region: (Secn:Picked), (Beam Orientation:Picked)
*Elset, elset=I1, generate
 1, 10,  1
** Section: Secn  Profile: Prof
*Beam Section, elset=I1, Section=RECT,material=Elas
1, 1
0.,0.,-1.
**Nset, nset=Set4
 **1,
**Nset, nset=_Set5, internal, instance=Beam2d-1
** 3,
** 
** MATERIALS
** 
*Material, name=Elas
*Density
10.,
*Elastic
 1e+08,0.
*step
*frequency,eigen=lanc
6,
*boundary
1,1,6
2,1,6
3,1,6
*node print 
u,
*end step
*STEP
*substructure generate, type=z1, overwrite, 
recovery matrix=yes, mass matrix=yes,
libr=lib_rbm_beam2d
*RETAINED NODAL DOFS
**,sorted=no
1,1,6
2,1,6
3,1,6
*SELECT EIGENMODES
1,2,3,4,5,6
*substructure matrix output, stiffness=yes, 
mass=yes, recovery=yes, file=lib_rbm_beam2d
*END STEP