Fatigue Reliability Assessment of Long-Span Steel-Truss Suspension Bridges under the Combined Action of Random Traffic and Wind Loads

This paper presents an efficient framework for the fatigue reliability assessment of typical long-span steel-truss suspension bridges under the combined action of random traffic and wind loads based on a stress analysis approach. The Aizhai Bridge in China was selected as an example to demonstrate the numerical procedure for this framework. In the numerical analysis, the critical locations of the bridge were first determined by refined finite-element analyses, and 30,000 samples of random input parameters (random wind field and traffic flow) were generated. Subsequently, the corresponding dynamic stress responses at the critical locations of the bridge were obtained via a stress analysis approach under the combined action of random traffic and wind loads. Finally, the fatigue reliability of the bridge was assessed considering the influence of the wind load, traffic growth, and vehicle axle load growth. The results show that both the wind and traffic loads have certain effects on the fatigue reliability of the bridge. The upper and lower chords of the main truss at one-fourth of the span, which is sensitive to both the wind and vehicle loads, should be given more attention.