Ansys瞬态分析的疑惑

本人在做一个中承式系杆拱的ansys动力响应分析，建模、静力计算、模态分析，都没有什么问题，感觉结果都很正常。可是在移动荷载作用瞬态分析的时候，计算的结果却是荷载初始加在边跨支点上，中跨跨中的竖向位移响应便达到最大，然后随着荷载由一边跨移动至另一边跨，中跨跨中的竖向位移整体呈现慢慢减小的趋势。这明显是不正确的，所以想问问各位大侠：
1、瞬态分析需要注意哪些细节内容？
2、为什么会出现这样的计算曲线（支点处竖向约束是加了的）？我将荷载值变为0，重新计算一次，依然出现这样的情况，非常不解。


/solu
antype,transient
TRNOPT,full

mp,damp,1,,0.04 !输入材料阻尼
mp,damp,3,,0.04
mp,damp,8,,0.04
mp,damp,9,,0.04
mp,damp,12,,0.04
mp,damp,13,,0.04
mp,damp,15,,0.04
mp,damp,2,,0.003
mp,damp,4,,0.003
mp,damp,5,,0.003
mp,damp,6,,0.003
mp,damp,7,,0.003
mp,damp,10,,0.003
mp,damp,11,,0.003
mp,damp,14,,0.003
mp,damp,16,,0.003
mp,damp,17,,0.003

!创建移动荷载点数组1
z0=13.8
nsel,s,loc,z,z0
*GET,Nmax,node,,COUNT
*DIM,nn,ARRAY,nmax,1,1
*do,i,1,nmax
*get,xmin,node,0,mnloc,x
nn(i)=node(xmin,15.795,z0)
nsel,u,loc,x,xmin-0.01,xmin+0.01
*enddo
allsel

!创建移动荷载点数组2
z1=-13.8
nsel,s,loc,z,z1
*GET,Nmax,node,,COUNT
*DIM,nm,ARRAY,nmax,1,1
*do,i,1,nmax
*get,xmin,node,0,mnloc,x
nm(i)=node(xmin,15.795,z1)
nsel,u,loc,x,xmin-0.01,xmin+0.01
*enddo
allsel


!定义加载车辆参数
v=10 !过桥车速v
p1=80000 !前轴重
p2=270000 !后轴重
w=20 !车振频率
de1=2.4
de2=2
det1=de1*3.6/v
det2=de2*3.6/v
bn1=30
bn2=83

outres,all,all
nsubst,2
*do,i,1,nmax+2
*if,i,le,2,then
tv=i*det1
time,tv
fdele,all,all
f,nn(i),fy,-p1*(1/2+cos(w*tv)/2)
f,nm(i),fy,-p1*(1/2+cos(w*tv)/2)
solve

*elseif,i,le,bn1
tv=i*det1
time,tv
fdele,all,all
f,nn(i),fy,-p1*(1/2+cos(w*tv)/2)
f,nn(i-2),fy,-p2*(1/2+cos(w*tv)/2)
f,nm(i),fy,-p1*(1/2+cos(w*tv)/2)
f,nm(i-2),fy,-p2*(1/2+cos(w*tv)/2)
solve

*elseif,i,le,bn2
tv=(i-bn1)*det2+bn1*det1
time,tv
fdele,all,all
f,nn(i),fy,-p1*(1/2+cos(w*tv)/2)
f,nn(i-2),fy,-p2*(1/2+cos(w*tv)/2)
f,nm(i),fy,-p1*(1/2+cos(w*tv)/2)
f,nm(i-2),fy,-p2*(1/2+cos(w*tv)/2)
solve

*elseif,i,le,nmax
tv=(i-bn2)*det1+(bn2-bn1)*det2+bn1*det1
time,tv
fdele,all,all
f,nn(i),fy,-p1*(1/2+cos(w*tv)/2)
f,nn(i-2),fy,-p2*(1/2+cos(w*tv)/2)
f,nm(i),fy,-p1*(1/2+cos(w*tv)/2)
f,nm(i-2),fy,-p2*(1/2+cos(w*tv)/2)
solve

*elseif,i,le,nmax+2
tv=(i-bn2)*det1+(bn2-bn1)*det2+bn1*det1
time,tv
fdele,all,all
f,nn(i-2),fy,-p2*(1/2+cos(w*tv)/2)
f,nm(i-2),fy,-p2*(1/2+cos(w*tv)/2)
solve

*endif
*enddo

[ 本帖最后由 diqiweili 于 2011-4-11 10:12 编辑 ]