Approximate Analysis of Nonstationary Random Vibrations of MDOF Systems

This paper considers the nonstationary response of classically-damped MDOF linear systems to a general class of nonstationary non-white excitations. A new approximate method is developed to considerably simplify the equations for the covariance of the response. The method of analysis provides the general conditions involving the system and excitation characteristics for which the approximations are reliable. The derived simplified equations reveal the similarities between the nonstationary and stationary response, and they provide valuable insight into the nonstationary response characteristics. The performance of the new method is demonstrated by numerical examples.