我自定义截面，采用梁格法，用beam44单元建立桥梁模型，在车辆移动荷载

作用下求某根梁的跨中弯矩广义影响线，按理论来说应该是正数值，为什么

我的却是负数值呢？命令流如下，求各位高手指点。
/TITLE,qiao
B=1.57
H=0.9
R=0.29
D=0.18
E=3.26E10
P=2500
/PREP7
ET,1,PLANE82
BLC4,,,B,H
CYL4,B*43/157,H/2,R
CYL4,B*114/157,H/2,R
ASBA,1,2
ASBA,4,3
ESIZE,0.1
MSHAPE,0,2D
MSHKEY,0
AMESH,ALL
SECWRITE,KXB,SECT,,1
SECTYPE,1,BEAM,MESH
SECOFFSET, CENT
SECREAD,KXB,SECT,,MESH
ACLEAR,1
ADELE,1, , ,1
ETDELE,1
/VIEW,1,1,1,1
ET,1,BEAM44
KEYOPT,1,6,1
MP,EX,1,E
MP,DENS,1,P
MP,PRXY,1,0.2
ET,2,BEAM44
MP,EX,2,E
MP,DENS,2,0
MP,PRXY,2,0.2
ET,3,BEAM44
KEYOPT,3,8,111
MP,EX,3,E
MP,DENS,3,0
MP,PRXY,3,0.2
ET,4,SHELL63
MP,EX,4,E
MP,DENS,4,P
MP,PRXY,4,0.2
R,4,D,D,D,D
N,1
N,11,,,20
FILL,1,11
N,12,0,2
NGEN,7,100,1,12,1,B
NGEN,2,1000,1,11,1,0,2
TYPE,1
SECNUM,1
MAT,1
*DO, I,1,10,1
*DO,K,1,7,1
E,(K-1)*100+I,(K-1)*100+I+1,(K-1)*100+12
*ENDDO
*ENDDO
TYPE,3
MAT,2
SECNUM,1
*DO,I,1,11,1
*DO,K,1,6,1
E,(K-1)*100+I,K*100+I,1000+I
*ENDDO
*ENDDO
K,1,0,(D+H)/2
K,2,6*B,(D+H)/2
K,3,6*B,(D+H)/2,20
K,4,0,(D+H)/2,20
A,1,2,3,4
WPROTA,,,90
WPOFFS,,,5*B
ASBW,ALL
WPOFFS,,,1.8-B
ASBW,ALL
WPOFFS,,,3*B/2-1.8
ASBW,ALL
WPCSYS,-1
ALLSEL,ALL
TYPE,4
MAT,4
REAL,4
LSEL,S,TAN1,Z
LSEL,R,LOC,X,0,5*B
LESIZE,ALL,,,10
ALLSEL,ALL
LSEL,S,TAN1,Z
LSEL,R,LOC,X,5*B,6*B
LESIZE,ALL,,,1
ALLSEL,ALL
LSEL,S,TAN1,X
LESIZE,ALL,,,50
ALLSEL,ALL
MSHAPE,0,2D
MSHKEY,1
AMESH,ALL
CPCYC,ALL,0.0001,,,(D+H)/2
NSEL,S,LOC,Y,0
NSEL,R,LOC,Z,0
D,ALL,UX,,,,,UY,UZ,ROTY,ROTZ
ALLSEL,ALL
NSEL,S,LOC,Y,0
NSEL,R,LOC,Z,20
D,ALL,UX,,,,,UY,ROTY,ROTZ
ALLSEL,ALL
NUMMRG,ALL
NSEL,S,LOC,Y,(D+H)/2
NSEL,R,LOC,X,4*B
*SET,NMAX,NDINQR(0,13)
*SET,NQ,1123
*SET,NR,1675
*DIM,PNODE,,2,NMAX
*DIM,NODEZ,,NMAX
*SET,PNODE(1,1),NQ
*SET,PNODE(2,1),NR
*SET,NODEZ(1),NZ(NQ)
*DO,I,2,NMAX
*SET,NI,NNEAR(NQ)
*SET,PNODE(1,I),NI
*SET,NODEZ(I),NZ(NI)
NSEL,U,,,NQ
*SET,NQ,NI
*ENDDO
NSEL,S,LOC,Y,(D+H)/2
NSEL,R,LOC,X,4*B+1.8
*DO,J,2,NMAX
*SET,NJ,NNEAR(NR)
*SET,PNODE(2,J),NJ
NSEL,U,,,NR
*SET,NR,NJ
*ENDDO
ALLSEL,ALL
FINISH
/SOL
*DO,I,1,NMAX
TIME,I
FDELE,ALL,ALL
*IF,I,LE,9,THEN
F,PNODE(1,I),FY,-30000
F,PNODE(2,I),FY,-30000
*ELSEIF,I,GE,10,AND,I,LE,12
F,PNODE(1,I),FY,-30000
F,PNODE(2,I),FY,-30000
F,PNODE(1,I-9),FY,-60000
F,PNODE(2,I-9),FY,-60000
*ELSEIF,I,GE,13
F,PNODE(1,I),FY,-30000
F,PNODE(2,I),FY,-30000
F,PNODE(1,I-9),FY,-60000
F,PNODE(2,I-9),FY,-60000
F,PNODE(1,I-12),FY,-60000
F,PNODE(2,I-12),FY,-60000
*ENDIF
SOLVE
*ENDDO
FINISH
/POST1
*DIM,BIAO,TABLE,NMAX,NMAX
*DIM,TRANS_V,ARRAY,NMAX-1
*DO,I,1,NMAX
SET,I
ETABLE,MZJ,SMISC,12
*SET,BIAO(0,I),I
*SET,BIAO(I,0),I
*SET,BIAO(I,1),NODEZ(I,1)
*VGET,TRANS_V,ELEM,34,ETAB,MZJ
*MFUN,BIAO(I,2),TRAN,TRANS_V
*ENDDO
/AXLAB,X,LENGTH
/XRANGE,0,20
/GROPT,DIVX,20
/AXLAB,Y,MOMENT_34
*VPLOT,BIAO(1,1),BIAO(1,2)