求大佬帮助下

小白学习中，遇到一个问题，下面两段命令流
FINISH $/CLEAR $/FILENAME,TM1105 $/PREP7
ET,1,BEAM189,1 $MP,EX,1,2E8 $MP,PRXY,1,0.3
SECTYPE,1,BEAM,I $SECDATA,0.5,0.5,0.8,0.012,0.012,0.01
SECOFFST,CENTE
K,1 $K,2,5 $K,3,10 $K,100,,,100 $L,1,2 $L,2,3 $LATT,1,,1,,,100,,1
LESIZE,ALL,0.25 $LMESH,ALL
/ESHAPE,1 $/REPLOT $FINISH
/SOLU
DK,1,UY,,,,UZ,ROTX $DK,3,UX,,,,UY,UZ,ROTX $FK,2,FZ,-1
ANTYPE,0 $OUTRES,ALL,ALL $PSTRES,ON $SOLVE $FINISH
/SOLU $ANTYPE,1
BUCOPT,LANB,5,,,range $MXPAND,5 $OUTRES,ALL,ALL $SOLVE $FINISH
/POST1 $/ESHAPE,0 $SET,LIST $SET,1,1$PLNSOL,U,Y $FINISH
以及
FINISH $/CLEAR $/FILENAME,TM1105 $/PREP7
ET,1,BEAM189,1 $MP,EX,1,2E8 $MP,PRXY,1,0.3
SECTYPE,1,BEAM,I $SECDATA,0.5,0.5,0.8,0.012,0.012,0.01
SECOFFST,ORIGIN
K,1 $K,2,5 $K,3,10 $K,100,,,100 $L,1,2 $L,2,3 $LATT,1,,1,,,100,,1
LESIZE,ALL,0.25 $LMESH,ALL
/ESHAPE,1 $/REPLOT $FINISH
/SOLU
DK,1,UY,,,,UZ,ROTX $DK,3,UX,,,,UY,UZ,ROTX $FK,2,FZ,-1
ANTYPE,0 $OUTRES,ALL,ALL $PSTRES,ON $SOLVE $FINISH
/SOLU $ANTYPE,1
BUCOPT,LANB,5,,,range $MXPAND,5 $OUTRES,ALL,ALL $SOLVE $FINISH
/POST1 $/ESHAPE,0 $SET,LIST $SET,1,1$PLNSOL,U,Y $FINISH
两个命令流区别在于梁的截面偏置位置不同，目的是获取集中力分别在用于工字梁质心和截面底部的屈曲荷载，但是运行后得到的结果是相同的(理论上结果应该不同)，这是为什么？或者有没有其他方法使集中力作用在梁单元截面不同高度上？