08-10-2014, 04:02 PM
The stochastic response of a suspension bridge including the dynamic soilstructure interaction (SSI) effects to spatially varying earthquake excitations has been studied. Since the currently available procedures for the stochastic analyses of structural systems cannot be generalized to the case of suspension bridges, particularly when the SSI effects have to be accounted for, an alternative approach has been formulated in frequency-domain for the non-stationary seismic analyses of simple SDOF and MDOF systems. This approach is then extended to the formulation for suspension bridges by considering fixed-base modes and by modifying the excitations at different supports for the soilstructure interaction effects. The proposed formulation requires the characterization of ground motion in form of a coherency function, and the values of peak ground acceleration (PGA), Fourier spectrum and strong motion duration. The proposed approach has been validated via time-history analyses for two sets of synthesized spatially correlated accelerograms. For generating these accelerograms,