PROBABILISTIC EVALUATION OF VORTEX-INDUCED VIBRATION OF BRIDGES BASED ON RELIABILITY THEORY

Vortex-induced vibration (VIV) that involves many uncertain factors is an aerodynamic phenomenon that occurs in long-span bridges at low wind speeds. The safety assessment on this kind of wind-induced vibration based on reliability theory is the research trend of long-span bridges. Three failure modes of bridge VIV wind speed, maximum amplitude and VIV stiffness based on the intersections of first two failure modes are investigated. Then, a long-span bridge is taken as an example to calculate the VIV amplitude failure probability using a second-order fourth-moment method. The calculation results are compared with those by a second-order second-moment method and verified by Monte Carlo simulation method (MC). It finds that the reliability analysis based on the second-order fourth-moment method has higher precision than that due to the second-order second-moment method. Afterwards, on account of the calculation result using the second-order fourth-moment method, the probability of bridge VIV stiffness failure is obtained. The investigations illustrate that the failure probability trend is conservative when individually considering the VIV wind speed or the amplitude of a long-span bridge.