Aerodynamic behavior of long-span cable-stayed bridges

The paper discusses the behavior of the aerodynamic fan-shaped scheme of cable-stayed bridges under wind load. A numerical analysis is developed, based upon time integration of the motion equations of the discretized structure. The main structural nonlinearity arising from the stress-strain stay's constitutive equation is taken into account together with the nonlinear effects that arise assuming a nonstationary model for aerodynamic loads. A Newmark's type algorithm is used to discuss first the problem of free oscillations in still air, and to determine next the critical wind speeds, both in the case of A-shaped and of H-shaped towers. For the latter case, the overall discrete model is validated by comparison with analytical results obtained by a continuous model, already developed.