Control of cables nonlinear vibrations under turbulent wind action

Steel cables are structural elements adopted in several engineering applications. Their high strength and light weight offer the designer a broad spectrum of solutions. On the other side their low inherent damping makes them prone to in-plane and out-of plane vibrations due to external actions such as bridge traffic and wind loads. Passive, semi-active and active control solutions have been proposed to reduce undesired levels of cables in-plane vibrations. In this paper a passive control solution is extended to out-of-plane wind excitations and is analyzed for a family of nonlinear hinged suspended cables. A semi-active solution derived from the previous one is also proposed. The dependence of the control effectiveness on the cable initial sag is investigated under several wind realizations through numerical simulations. The cable response in terms of axial force and amplitude of displacements is seen to be highly reduced by the proposed control strategies for a wide range of initial sag. Control difficulties are observed in the case of internal resonance conditions. The numerical simulations are conducted by a finite element method approach and the wind load is simulated as a multivariate mono-dimensional Gaussian process applied along the cable.