Wind Resistance Performance Assessment of Long-Span Cable-Supported Bridges Based on Time-Varying Reliability Theory

Long-span cable-supported bridges constitute the most common type of bridge with a span of more than 400 m. They are generally designed as a double-tower long-span structure with good spanning capacity and economic performance. Wind resistance safety performance is the main index used to control the long-span cable-supported bridge structure. During the life of a long-span cable-supported bridge structure, because the service life of the cables is far shorter than the design life of the structure, the wind resistance performance of the structure will inevitably deteriorate significantly, which will seriously affect the structural service performance of symmetric cable-supported bridges. Under strong wind loads, the static wind stability and flutter stability of cable-stayed bridge structures are components of the limit state of bearing capacity, which directly affects the safety performance of the structure. We take the flutter and static wind stability of a long-span cable-supported bridge structure as the main design control index, use inverse reliability theory to calculate the reliability index of a symmetric cable-supported bridge structure, use inverse reliability theory to calculate the safety factor of a symmetric cable-supported bridge structure, and evaluate the time-varying wind resistance performance of a long-span cable-supported bridge structure by comprehensively considering the reliability index and safety factor. Taking a practical project concerning a long-span cable-supported bridge as a specific case, the time-varying wind resistance reliability of the bridge throughout its operation for more than 30 years is analyzed along with the parameter sensitivity. The results show that the wind resistance performance of the cable-supported bridge structure is obviously affected by its cables, and the degradation of cable performance will have a significant impact on the time-varying wind resistance performance of the structure, especially the critical wind speed of the structure, which has obvious time-varying characteristics. The safety factor and reliability index can be used to objectively evaluate the time-varying wind resistance performance of long-span cable-supported bridge structures.