*HEADING
 RING BUCKLE EIGENVALUE ESTIMATE  3 - B21        
*NODE
1,100.       ,            ,  ,  -1.
4,70.71067812,70.71067812 ,  ,  -1. , -1.
*NGEN,LINE=C
1,4,1,0,0.,0.
*ELEMENT,TYPE=B21,ELSET=ONE
1,1,2
*ELGEN,ELSET=RING
1,3
*BEAM SECTION,SECTION=RECT,MATERIAL=A1,ELSET=RING
1.,1.
0.,0.,-1.
*MATERIAL,NAME=A1
*ELASTIC
30.E6,0.
*NSET,NSET=END
4, 
*TRANSFORM,NSET=END
1.,1.,0.,-1.,1.,0.
*BOUNDARY
1,2
1,6
4,2
4,6
*STEP,NLGEOM
*BUCKLE
3,
*BOUNDARY,LOAD CASE = 2, OP=NEW
1,2
1,6
4,1
*DLOAD
RING,P2,1.
*EL PRINT,FREQUENCY=0
*NODE PRINT ,SUMMARY=NO
U,RF
*MODAL PRINT
*MODAL FILE
*OUTPUT,FIELD,VAR=PRESELECT
*END STEP