D()+25)D+c2D()=-y2() mx(o 对于单自由度体系 x+22+O2x=-x,(t) fig()e)sin oa(t-T)d 对于振型折算体系(右图) Ve so,(t SIn o ) (t-t)dt D(1)=3 x2()e SIn a (t-r)dr x2() y,△,(t) j=1,2,…N( ) 2 ( ) ( ) 2 D t D D t x t j j j j j j j g    +   + = − x(t) x (t) g m 2 ( ) 2 x x x x t g  +   + = −  = − − − − t t x t x e t 0 d ( ) g d ( ) sin ( )d 1 ( )          = − − − − t j t j D t x e t j j 0 j ( ) g j ( ) ( ) sin  (  )d       (t) = j  j    = − − − − t t j t x e t j j 0 j ( ) g j ( ) sin ( )d 1 ( )          (t)  j x (t) g * M j j   j 对于单自由度体系 对于j振型折算体系（右图） j =1,2, N