Constant velocity motion of a structure

This is my inp file:

*INCLUDE, INPUT=all.msh
*INCLUDE, INPUT=interface_beam.nam
*INCLUDE, INPUT=Nlr.nam

*MATERIAL, Name=EL
*ELASTIC
 73100000000, 0.33
*DENSITY
 3000
*SOLID SECTION, Elset=Eall, Material=EL

*STEP, NLGEOM, INC=1000000
*DYNAMIC, ALPHA=0.01, DIRECT
*DAMPING,ALPHA=0.01,BETA=0.0004
1E-5, 1.0



*AMPLITUDE, NAME=RAMP_X
0.0, 0.0
1.0, 40

*AMPLITUDE, NAME=RAMP_Y
0.0, 0.0
1.0, -1.5

*BOUNDARY, AMPLITUDE=RAMP_X
Nlrmoving, 1, 1, 1

*BOUNDARY, AMPLITUDE=RAMP_Y
Nlrmoving, 2, 2, 1



*BOUNDARY
Nall, 3



*CLOAD
 Nsurface, 1, 0.0
 Nsurface, 2, 0.0
 Nsurface, 3, 0.0
*NODE FILE
 U,V
*EL FILE
 S, E
*END STEP