Passive Control Strategy for Wind-induced Parametric Instabilities in Suspension Bridges

A nonlinear reduced-order model of suspension bridges (SB) is presented to study the dynamical response and to investigate aerodynamic stability control strategies coping with vortex-induced vibrations (VIV) leading to principal parametric resonances scenarios. A passive control system consisting of a vibration absorber is incorporated in the model by coupling the dynamics of the bridge with those of an eccentric mass viscoelastically connected to the deck. A direct asymptotic approach is used to investigate the dynamic instabilities induced by the parametric-type forces in the case of a 2:1 ratio between the frequency of the aerodynamic loads and the fundamental torsional frequency of the bridge. It is shown how an optimized passive control system can increase the range of wind speeds for which the bridge does not undergo large-amplitude parametric oscillations signaling the loss of stability of the fundamental equilibrium configuration.