08-10-2014, 04:29 PM
A mode acceleration formulation is presented to investigate the variability in the responses of a secondary system which is supported on a flexible-base primary system at multiple attachment points. The response functions are considered to be uncertain due to the uncertainty in the shear wave velocity and Poisson's ratio of the foundation soil. Both soil parameters are assumed to be independent variables with Gaussian distributions. A numerical study with the help of two example P-S systems and three example excitation processes shows that dynamic response should be considered for as many secondary modes as possible for the given formulation to work well, and that uncertainties in the soil parameters directly affect the transfer functions near the first few peaks and crests. A perturbation approach is also formulated for determining the combined system properties in case of light secondary systems. A numerical study is carried out to illustrate the accuracy achieved with the proposed formulation, even when not all primary and secondary modes are considered. Considering