Random vibration of rotating machines under earthquake excitations

Random vibration of rotating machines subjected to seismic excitations is analyzed in which the six-component earthquake ground motions are modeled as nonstationary random processes. The six-component earthquake inputs including the rotational components of base excitations, result in notonly nonhomogeneous excitations but also parametric excitations. Thus, the classical spectral analysis of random vibration is not applicable. Furthermore, both nonhomogeneous and parametric random excitations are correlated random processes, making the problem even more difficult to solve analytically. To date random vibration of such a complicated problem has not been investigated. The method of Monte Carlo simulation is used to simulate the sixcomponent nonstationary earthquake ground motions and to determine the statistics of the response of rotating machines. The significance of seismic base otations on the overall structural response is examined. A numerical example is worked out to demonstrate the methodology employed.