Dynamic Amplification Factor Characteristic Analysis of an Arch Bridge Under Traffic and Varying Road Surface Roughness

Road surface deterioration can significantly amplify bridge vibration responses under traffic loading; however, the evolution of bridge dynamics under progressively deteriorating road conditions remains insufficiently understood. This study aims to investigate the statistical characteristics and evolution of the dynamic amplification factor (DAF) of a tied-arch bridge under realistic traffic conditions over its service life.

A three-dimensional finite element (FE) model of the bridge is developed in ANSYS and coupled with a stochastic traffic flow model based on the cellular automaton (CA) method. A time-dependent road surface deterioration model is incorporated to simulate the evolution of road roughness. Extensive numerical simulations are performed, and the statistical distribution of DAF is analyzed using the generalized extreme value (GEV) model.

The results show that the GEV distribution provides a more accurate representation of DAF than the conventional normal distribution. The DAF exhibits significant spatial variability across structural components and increases in both magnitude and dispersion with progressive road surface deterioration. Conventional design values are found to underestimate vehicular impact effects under deteriorated conditions. A predictive relationship between road surface roughness and the statistical parameters of DAF is established.

The proposed framework enables a more realistic evaluation of bridge dynamic performance under stochastic traffic loading and progressive road degradation, providing valuable insights for long-term bridge design and maintenance.