*HEADING
:  ADDED MASS LOADS ON TRUSS ELEMENTS
**
**  STEP 1:  EIGENVALUE EXTRACTION WITH D ADDED MASS
**
**     f_n = (n - 0.5)*(1/2L)*sqrt(E/(rho+rhow))
**
**           Mode   cycles/time    ABAQUS
**     ---------------------------------------
**            1       3.9959       3.9958
**            2       11.988       11.986
**            3       19.979       19.974
**            4       27.971       27.957
**
**  STEP 2:  EIGENVALUE EXTRACTION WITH NO ADDED MASS
**
**     f_n = (n - 0.5)*(1/2L)*sqrt(E/rho)
**
**           Mode   cycles/time    ABAQUS
**     ---------------------------------------
**            1       4.2554      4.2554
**            2       12.766      12.765 
**            3       21.277      21.272
**            4       29.788      29.773   
**
**  STEP 3:  EIGENVALUE EXTRACTION WITH C ADDED MASS
**
**     Results are the same as those from STEP 1
**
**
*RESTART,WRITE
*NODE
  1,    0.0,
101, 1000.0,
*NGEN,NSET=NTR
1,101
*NSET,NSET=NTRMID,GEN
2,100
*ELEMENT,TYPE=T3D2
   1,   1,   2
*ELGEN,ELSET=TR_STEEL
   1,100,1,1
**
*SOLID SECTION,ELSET=TR_STEEL,MATERIAL=STEEL1
28.2743,
**
*MATERIAL,NAME=STEEL1
*ELASTIC
4.32E9,
*DENSITY
14.91,
**
*AQUA
-100.0,100.0,32.2,2.0
**
*STEP
STEP 1:  EIGENVALUES WITH D ADDED MASS LOADS
*FREQUENCY, eigensolver=lanczos, SIM=NO
4, , 
*D ADDED MASS
TR_STEEL,FI1,1.,141.37
TR_STEEL,FI2,1.,141.37
*BOUNDARY
1,1
NTR,2,3
*MODAL FILE
*NODE FILE
RF, 
*END STEP
**
*STEP
STEP 2: NO D ADDED MASS 
*FREQUENCY, eigensolver=lanczos, SIM=NO
4, , 
*BOUNDARY,OP=NEW
1,1
NTR,2,3
*MODAL FILE
*NODE FILE
RF, 
*END STEP
**
*STEP
STEP 3: C ADDED MASS LOADS- EIGENVALUES SHOULD EQUAL THOSE OF STEP 1
*FREQUENCY, eigensolver=lanczos, SIM=NO
4, , 
*C ADDED MASS
NTRMID,TSI,1.0, 282.74
-1,0,0
  1,TSI,1.0, 141.37
-1,0,0
101,TSI,1.0, 141.37
-1,0,0
*BOUNDARY,OP=NEW
1,1
NTR,2,3
*MODAL FILE
*NODE FILE
RF, 
*END STEP