如何让附加的荷载不进入大变形的子步

naegueli

各位大牛：
命令流如下，如何让红色的附加荷载不进入大变形的子步，盼大虾指点！

!Modeling of Truss
fini
/clear
/units,si
/config,nres,10000
k=1.2
a=0.15
t=0.075
Ad=(3*(1+k^2)^1.5)*a*t/(16*k)
Ah=(3*(3-k^2)*a*t/8
Av=(3*(3*k^2-1))*a*t/(8*k)
/prep7
ET,1,link8
ET,2,beam188
R,1,Ah          !Ah
R,2,Av          !Av
R,3,Ad          !Ad
R,4,1.4124e-4   !H1
R,5,9.4163e-5   !H2
R,6,1.06e-4     !V1
!R,7,4.32e-4    !V2
R,8,5.03e-4     !mixed layers of reinforcement
R,9,0.075*0.18  !multi-layered beams of concrete
R,10,0.2*0.2    !top slab
parameters of reinforcement 6
MP,DENS,1,7850
MP,EX,1,1.96E+11
MP,PRXY,1,0.3  
TB,BKIN,1,1,2,1
TBDATA,,345,0,,,,  
!parameters of reinforcement 8
MP,DENS,2,7850
MP,EX,2,2.01E+11
MP,PRXY,2,0.3  
TB,BKIN,2,1,2,1
TBDATA,,527,0,,,,  

!parameters of concrete
MP,DENS,3,2500   
MP,EX,3,3.266e10   
MP,PRXY,3,0.2  
TB,KINH,3,1,8,0
TBPT,,0.0005,16.33e6   
TBPT,,0.001,28.00e6
TBPT,,0.0015,35.00e6   
TBPT,,0.002,37.33e6   
TBPT,,0.0025,37.33e6  
TBPT,,0.00275,37.33e6
TBPT,,0.003,37.33e6
TBPT,,0.0033,37.33e6  

!multi-layered beams of concrete
SECTYPE,1,BEAM,RECT,,0
SECOFFSET,CENT
SECDATA,0.180,0.075
!top slab
SECTYPE,2,BEAM,RECT,,0
SECOFFSET,CENT
SECDATA,0.2,0.9
!building of nodes
*DO,i,1,16
*DO,j,1,4
   N,(i-1)*4+j,(j-1)*0.24,(i-1)*0.15
  *ENDDO
*ENDDO

!modeling of reinforcement truss
MAT,1
TYPE,1
!h1
REAL,4
*DO,i,5,7
  E,i,i+1
  E,i+52,i+53
*ENDDO
!h2
REAL,5
*DO,i,2,13
  *DO,j,1,3
    E,i*4+j,i*4+j+1
  *ENDDO
*ENDDO
!V1
REAL,6
*DO,i,2,58,4
  E,i,i+4
  E,i+1,i+5
*ENDDO

!mixed layers of reinforcement
REAL,8
*DO,i,1,57,4
  E,i,i+4
*ENDDO
*DO,i,4,60,4
  E,i,i+4
*ENDDO
!modeling of concrete truss
MAT,3
TYPE,1
!Ah
REAL,1
*DO,i,1,16
  *DO,j,1,3
    E,(I-1)*4+J,(I-1)*4+J+1
  *ENDDO
*ENDDO
!Av
REAL,2
*DO,i,1,4
  *DO,j,1,15
    E,i+(j-1)*4,i+j*4
  *ENDDO
*ENDDO
REAL,3
*DO,i,1,15
  *DO,j,1,3
    E,(i-1)*4+j,(i-1)*4+j+5
  *ENDDO
*ENDDO
*DO,i,1,15
  *DO,j,2,4
    E,(i-1)*4+j,(i-1)*4+j+3
  *ENDDO
*ENDDO

MAT,3
TYPE,2
REAL,9
SECNUM,1
*DO,i,1,57,4
  E,i,i+4
*ENDDO
*DO,i,4,60,4
  E,i,i+4
*ENDDO
MAT,3
TYPE,2
REAL,10
SECNUM,2
*DO,i,61,63
E,i,i+1
*ENDDO
!/pnum,elem,1
!eplot

finish
/solu
antype,0
allsel
nsel,s,loc,y,0
d,all,all
!nsel,s,loc,y,2.25
!d,all,uy
!d,all,uz
!d,all,rotx
!d,all,roty
!d,all,rotz
allsel
*DO,i,61,64
F,i,FX,22000.0
*ENDDO
allsel
*DO,i,61,64
F,i,Fy,-50000
*ENDDO

nlgeom,1 !激活大位移选项
outres,all,all !输出每一子步的结果
nsubst,200 !定义子步数为10
arclen,1
solve
finish
/post26
nsol,2,64,u,x
varnam,1,load-ux
xvar,2  
/axlab,x,ux
/axlab,y,load   
/xrange,0,0.02
/Yrange,0,1
/grid,1
plvar,1