Rapid risk assessment of multiple buffeting performance levels for long-span bridges

The wind-sensitive long-span bridges under buffeting loads are currently designed to be limited to linear, elastic behavior but may present unfavorable performance in terms of driving/pedestrian comfort. Furthermore, the lack of consideration on global climate change (with intensified windstorms) and local thermodynamics process (with energetic convective turbulence) in design wind loads may lead to nonlinear, inelastic behaviors of existing bridges associated with various damage levels to structural components (e.g., negligible, repairable, or severe damage states). Accordingly, rapid risk assessment of long-span bridge buffeting performance at multiple levels is needed. To this end, a closed-form solution is developed in this study by convolving the wind hazard function (fitted as a polynomial curve) with the structural fragility function (fitted as a lognormal curve) for risk evaluation with high efficiency. The Sutong Yangtze River Bridge is utilized as a case study for rapid risk (probability of damage) assessment of structural components (e.g., bridge deck, tower, and stay cable) under buffeting loads based on the proposed closed-form solution. To verify the efficiency and accuracy of the proposed approach, the buffeting risks calculated by the closed-form solution are compared with those obtained through the Monte Carlo simulations. Finally, parameter sensitivity analyses are conducted to reveal the important effects of the uncertainties related to wind fields, aerodynamic characteristics, and structural properties on the long-span bridge buffeting risks.