*HEADING
TORSIONAL BUCKLING: B31OS, *BEAM SECTION, SECTION=I
*RESTART,WRITE
*NODE
*NGEN,NSET=ALL
*ELEMENT,TYPE=B31OS
*ELGEN,ELSET=BEAM
*BEAM SECTION,SECTION=I,ELSET=BEAM,MATERIAL=MAT
 0.345,0.69, 0.3,0.3, 0.027,0.027, 0.0145
 0.0,-1.0,0.0
*MATERIAL,NAME=MAT
*ELASTIC
 2.1E11,0.3125
*BOUNDARY
 1,1,4
 21,2,4
*STEP
*BUCKLE
15,
*NODE PRINT
U,
RF  ,
*NODE FILE,FREQUENCY=1
U,RF
COORD,
*CLOAD
 21,1,-10.0
*EL PRINT,FREQUENCY=0
*MODAL FILE
*END STEP