Standard methods of structural dynamic analysis assume that the struct
ural characteristics are deterministic. Recognizing that these charact
eristics are actually statistical in nature, researchers have recently
developed a variety of methods that use this information to determine
probabilities of a desired response characteristic, such as natural f
requency, without using expensive Monte Carlo simulations. One of the
problems in these methods is correctly identifying the statistical pro
perties of primitive variables such as geometry, stiffness, and mass.
We present a method where the measured dynamic properties of substruct
ures are used instead as the random variables. The residual flexibilit
y method of component mode synthesis is combined with the probabilisti
c methods to determine the cumulative distribution function of the sys
tem eigenvalues. A simple cantilever beam test problem is presented th
at illustrates the theory.