ABSTRACT
Wind-induced phenomena analysis is a pivotal task in the design of long-span bridges under extreme wind load to achieve the required safety and resilience design goals. Several aeroelastic responses must be considered including serviceability limit states, such as buffeting and VIV, and ultimate limit states, such as flutter and aerostatic stability, which may jeopardize the integrity of the structure under the action of wind. While intense research has been conducted to understand the flutter response of long-span bridges and improve the flutter-resistant design techniques given the usual predominance of this phenomenon, research contributions focusing on aerostatic stability are scanter. Nevertheless, the progressive length increase of the main spans adopted in contemporary bridge designs has brought attention to aerostatic stability-resistant design as a required task to guarantee and increase the bridge safety and resilience along its lifespan. However, developing design frameworks focusing on the aerostatic stability of long-span bridges must deal with the nonlinear nature of this phenomenon, particularly influenced by the nonlinear structural characteristics. Nonlinear behavior of stays, large displacement effect, beam-column effect, the interdependence of lateral and torsional deck displacements, and nonlinear aerodynamics, among others, certainly increase the modeling demands and computational burden as well. In this study, the nonlinear aerostatic stability of a long-span cable-stayed bridge is analyzed using a nonlinear finite element model and an efficient modal-based method leveraged by a root-finding algorithm that permits a rapid identification of the critical wind velocity. Bridge deck aerodynamics as a function of the angle of attack are obtained by wind tunnel tests and CFD simulations for several deck shape geometries. Parametric studies are conducted to identify the most influential shape and size design variables to control the nonlinear aerostatic stability performance of the bridge.
