**SUBSTRUCTURE GENERATION FILE FOR substrframe_1level_2modes.inp
*NODE
1,
11,  ,2.4
*NGEN
1,11   
*ELEMENT,TYPE=B21,ELSET=COLUMN
1,1,2
*ELGEN,ELSET=COLUMN
1,10
*BEAM SECTION,SECTION=RECT,MATERIAL=STEEL,ELSET=COLUMN
0.1 , 0.1
*MATERIAL,NAME=STEEL
*ELASTIC
2.1E11 , 0.3
*DENSITY
7200.     ,   
**
*STEP
*FREQUENCY, EIGENSOLVER=LANCZOS
2,
*BOUNDARY
1,1,2,0
1,6,6,0
11,1,2,0
11,6,6,0
*EL PRINT,FREQUENCY=0
*END STEP
**
**
*STEP
*SUBSTRUCTURE GENERATE,TYPE=Z101,MASS MATRIX=YES,OVERWRITE
*RETAINED NODAL DOFS
1,
11,
*select eigenmodes,generate
1,2
*SUBSTRUCTURE MATRIX OUTPUT,STIFFNESS=YES,MASS=YES,SLOAD=YES,
FILE NAME=substrframe_1level_2mode_gen1
*END STEP