Abstract: High costs and significant traffic volumes characterize long-span suspension bridges, which play a crucial role in transportation networks. As a control engineering project, deterministic analysis methods, such as the finite element method, are currently employed to calculate and analyze the safety of these bridges. However, in practical engineering, structural parameters exhibit uncertainty，and simultaneously, variability and correlation exist in spatial distribution. Hence, the influence of random field factors is incorporated. A numerical analysis method, combined with random field and reliability theory, was proposed for the reliability assessment of long-span suspension bridges. The components and implementation process of the method were introduced, and corresponding analysis programs were developed. The accuracy and applicability of the method and programs were validated through several examples. Finally, taking the three-tower four-span suspension bridge, the Oujian North Bridge, as an engineering case, the reliability of its deflection under normal operating limit states was evaluated. The impact of random fields on the deflection reliability index of the Oujian North Bridge was analyzed. Results indicate that considering random fields yields a deflection reliability index smaller than that obtained without considering them, suggesting that the spatial variability of structural parameters in long-span suspension bridges is neglected, leading to an overestimation of deflection reliability in normal service limit states.

Key words: bridge engineering, suspension bridge, random field, first-order reliability method, finite element analysis, reliability index