*HEADING
 RING BUCKLE EIGENVALUE ESTIMATE  - 5 B21        
*NODE
1,100.
6,70.71067812,70.71067812
*NORMAL
 1, 1,  -1.
 5, 6, -1.,  -1.
*NGEN,LINE=C
1,6,1,0,0.,0.
*ELEMENT,TYPE=B21,ELSET=ONE
1,1,2
*ELGEN,ELSET=RING
1,5
*NSET,NSET=END
6, 
*BEAM SECTION,SECTION=RECT,MATERIAL=A1,ELSET=RING
1.,1.
0.,0.,-1.
*MATERIAL,NAME=A1
*ELASTIC
30.E6,0.
*TRANSFORM,NSET=END
1.,1.,0.,-1.,1.,0.
*STEP
*BUCKLE
1, 
*DLOAD
RING,P2,1.
*BOUNDARY
1,2
1,6
END,2
END,6
*BOUNDARY,LOAD CASE=2, OP=NEW
1,2
1,6
END,1
*NODE PRINT,SUMMARY=NO
U,RF
*EL PRINT,ELSET=ONE,SUMMARY=NO
S, 
*MODAL FILE
*OUTPUT,HISTORY,FREQUENCY=1
*MODAL OUTPUT
*END STEP