State-space modeling of systems with frequency dependent parameters

ABSTRACT: In this paper, a framework for studying the dynamics of systems with frequency dependent parameters, under stochastic loads, using the state-space modeling approach is presented. Particular emphasis is placed on the stochastic buffeting response of long span bridges under multicorrelated wind excitation. The buffeting response is expressed as the output of an integrated system driven by a vector-valued white noise process. The integrated state-space model allows direct evaluation of the covariance matrix of the response using the Lyapunov equation, which leads to higher computational efficiency than the conventional spectral analysis approach. The proposed model facilitates time domain simulation of the multi-correlated wind fluctuations, the associated frequency dependent aerodynamic forces and the induced structural motion. The effectiveness of this approach is demonstrated using a long span cable-stayed bridge.