*HEADING                                                                      
TORSIONAL BUCKLING:                    
B31OS, *BEAM GENERAL SECTION, SECTION=GENERAL 
*RESTART,WRITE
*NODE
 1,0.0,0.0,0.0
 21,12.0,0.0,0.0
*NGEN,NSET=ALL
 1,21
*ELEMENT,TYPE=B31OS
 1,1,2
*ELGEN,ELSET=BEAM
 1,20,1,1
*BEAM GENERAL SECTION,SECTION=GENERAL,ELSET=BEAM
 2.5422E-2, 2.092E-3,0.0, 1.2166E-4,4.5829E-6, 0.0, 1.3351908E-5  
 0.0,-1.0,0.0
 2.1E11,8E10
*BOUNDARY
 1,1,4
 21,2,4
*STEP
*BUCKLE
15,
*CLOAD
 21,1,-10.0
*OUTPUT, FIELD, MODE LIST
 1,2,4,5,6,7,8,9,10,11,12,13,14,15
*NODE OUTPUT
 U,
*NODE PRINT
 U, 
 RF, 
*END STEP