y Ax Nd=yAx+ a+0+=a (O+y Ax)+(2+r Ax) =(Q+y4x)1+ a =F.1+ st ag 引入记号Ka=1+ 动荷系数 则F=KaF,aa=Ka·sa g Q a Q g Ax F Ax Nd = + + +   动荷系数 = (Q + Ax) + (Q + Ax) a g   = ( + ) +      Q Ax  a g  1         = + g a Fst 1 引入记号 K a g d = 1+ FNd Kd Fst 则 =  ，  d = Kd  st 