Impact Behavior of Stiff Hangers in Arch Bridge Due to Moving Vehicles

In a half-through or through arch bridge, the hangers (or suspenders) are considered as critical structural components, especially for dynamic performance assessment. This paper aims to study the dynamic impact of stiff hangers in an arch bridge caused by moving vehicles. An iterative algorithm is firstly proposed to solve the three-dimensional coupling vibration between the vehicle(s) and the large-scale bridge. In addition, the uncertainty of the computed strain-based dynamic amplification factor (DAF) due to measurement noise and the relationship between the DAF and local stiffness degeneration are investigated, respectively. After that, the influences of several parameters on the strain-based DAF of the hangers are studied by parametric analyses, including vehicle speed, road surface conditions, loading lane, vehicle spacing and vehicle model. The results show that the proposed iterative algorithm can accurately solve the refined three-dimensional coupled vibration system, and that the strain-based DAF is sensitive to measurement noise and changes of local stiffness. The shortest hanger suffers a more serious impact effect and a higher dynamic fatigue risk. The analysis results of this study could provide some useful and practical recommendations for the routine maintenance and traffic management of arch bridges with stiff hangers.