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• Probabilistic vortex-induced vibration (VIV) occurrence prediction based on wind tunnel tests. • Prediction of the vortex-induced vibration occurrence using decision tree method. • Considering the effects of structural damping ratio, wind direction and wind speed. • Probabilistic cost-benefit analysis from Aerodynamic countermeasures (ACMs) application. The twin-box girder is a recommendable structural style for long-span cable-supported bridges due to its excellent aeroelastic stability. Vortex-induced vibration (VIV) is a typical wind-induced vibration for this kind of girder with a high occurrence probability associated with wind characteristics, structural properties and aerodynamic configuration under uncertainty. Therefore, probabilistic approaches should be adopted to predict the occurrence of VIV under uncertainty. This paper presents such an approach to predict the VIV occurrence using the decision tree method. Wind tunnel tests on a large-scale section model are conducted to investigate the effects of structural damping ratio and wind speed on VIV performance. Uniform and turbulent wind flow fields under three attack angles of −3°, 0°, and −3° are tested. Moreover, wind direction at the bridge site is determined as a parameter affecting VIV occurrence. As a result, a decision tree considering the effects of structural damping ratio, wind direction and wind speed is formulated to estimate the probability of VIV occurrence. In order to suppress VIV, aerodynamic countermeasures (ACMs) with L-shaped windshields are applied. Furthermore, the probabilistic cost-benefit analysis of the application of ACMs is developed using a decision tree, and the probability of the positive cost-benefit from ACMs application is accordingly estimated. The application of the proposed probabilistic approach is investigated on a long-span cable-stayed bridge with two separated steel boxes. [ABSTRACT FROM AUTHOR]

• A novel aerostatic stability analysis method using a modal formulation is presented. • Convergence to the critical wind velocity is accelerated through a root-finding algorithm in the outer loop. • The proposed method is applied to a cable-stayed bridge considering multiple nonlinear features. • The collapse is driven by stiffness degradation due to stays loss of tension and ultimately stiffness. • The influence of aerodynamic and structural nonlinear features on the critical wind velocity is investigated. An efficient method for analyzing the nonlinear aerostatic stability of long-span bridges using a modal formulation is proposed. First, a simplified linear version defined as modal-based approach is introduced, which evaluates the bridge displacements using the modal properties of the bridge and speeds up the assessment of the critical velocity by applying a root-finding algorithm. Then, this scheme is further developed to identify the instability limit point in nonlinear structures by combining nonlinear FEM analyses with the linear version of the modal-based approach and a root-finding algorithm in an outer loop. The effects of considering the three components of the wind loads, the stays sag effect, structural nonlinearities, aerodynamic nonlinearities, and the initial wind angle of attack, are analyzed and discussed. The computational advantages of the proposed method and its accuracy are demonstrated through three application examples, including a simplified linear 1 DoF system, and linear and nonlinear FEM models of a full cable-stayed bridge. The collapse mechanism of the cable-stayed bridge is driven by the stiffness degradation of the stays caused by the deck vertical upward displacements. It has been found that the influence of the nonlinear aerodynamic features is very low when the structural nonlinearities control the bridge collapse. [ABSTRACT FROM AUTHOR]