Aeroelastic stability of a symmetric multi-body section model

The aeroelastic stability of a multi-body system is studied through a four-degree-of-freedom elastic model, which describes the linearized section dynamics of particular suspended bridges with doubly-symmetric cross-section, subject to a lateral stationary wind flow. A multi-parameter perturbation solution, applied to the modal problem in internal resonance conditions, allows a consistent reduction of the model dimensions. Focus is made on the particular parameter region corresponding to the triple internal resonance among a global torsional mode of the deck and two local modes of a pair of hanger cables. The bifurcation scenario described by a local stability analysis is featured by two dynamic instability boundaries, strongly interacting with each other. The parametric analysis of the critical wind velocity provides satisfying engineering results, pointing out how the presence of resonant light cables, as well as the addiction of dissipative couplings simulating passive viscous dampers acting on the cable-deck differential velocity, may have beneficial effects in preventing the aeroelastic instability of the full system.