A simple analytical approach to the aeroelastic stability problem of long-span cable-stayed bridges

This paper deals with the aeroelastic stability problem of longspan cable-stayed bridges under an approaching crosswind flow. Starting from a continuous model of the fan shaped bridge scheme with both H- or A-shaped towers, critical states of the coupled wind structure system are identified by means of a variational formulation, accounting for torsional and flexural (vertical and lateral) bridge oscillations. The overall bridge dynamics is described by introducing simple mechanical systems with equivalent stiffness properties and, under the assumption of a prevailing trusslike bridge behavior, analytical estimates for dominant stiffness contributions are proposed. Several case studies are discussed and comparisons with experimental evidences as well as with available analytical and numerical results are presented. The proposed simplified approach proves to be consistent and effective for successfully capturing the main wind-bridge interaction mechanisms,and it could be considered as a useful engineering tool for the aeroelastic stability analysis of long-span cable-stayed bridges.