** SUBSTRUCTURE GENERATION FILE FOR substrframe_1level_2modes.inp
*NODE
1 ,
11 , 8.
*NGEN
1,11
*ELEMENT,TYPE=B21,ELSET=BEAM
1,1,2
*ELGEN,ELSET=BEAM
1,10
*BEAM SECTION,SECTION=RECT,MATERIAL=STEEL,ELSET=BEAM
0.1 , 0.1
*MATERIAL,NAME=STEEL
*ELASTIC
2.1E11 , 0.3
*DENSITY 
7200., 
**
**
*STEP
*FREQUENCY, EIGENSOLVER=LANCZOS
2,
*BOUNDARY
1 ,1,6
11,1,6
*EL PRINT,FREQUENCY=0
*END STEP
**
**
*STEP
*SUBSTRUCTURE GENERATE,TYPE=Z201,MASS MATRIX=YES,OVERWRITE
*RETAINED NODAL DOFS
1 ,1,6
11,1,6
*SELECT EIGENMODES
1,2
*SUBSTRUCTURE LOAD CASE, NAME=SNOW
*DLOAD
BEAM,PY , 1.
*SUBSTRUCTURE MATRIX OUTPUT,STIFFNESS=YES,MASS=YES,SLOAD=YES,
FILE NAME=substrframe_1level_2mode_gen2
*END STEP