Effect of Load Cases and Hanger-Loss Scenarios on Dynamic Responses of the Self-Anchored Suspension Bridge to Abrupt Rupture of Hangers

Abstract

Self-anchored suspension bridges with large prestressed girders have proven to be suitable bridge structures where external anchorage systems cannot be easily provided. However, these bridges cannot overcome the major limitation that their hangers may suddenly break under hazardous circumstances, which may cause the potential risk of progressive collapse. In this paper, the effects of hanger-loss scenarios and load cases on the structural performance of the self-anchored suspension bridge are studied. To conduct the investigation, several issues related to the nonlinear dynamic simulation are presented. The results obtained from a case study on a concrete self-anchored suspension bridge show that the dynamic effects caused by the hanger-breakage event are heavily dependent on the duration of the breakage process. Compared to the sudden breakage of a single hanger, the asymmetrical loss of two hangers can cause a large torsional moment in the girder and tensile stress in hangers. The influence of load cases on the structural dynamic responses is significant, while the effect on the dynamic amplification factor (DAF) corresponding to hangers and the stiffening girder is not obvious. In addition, it is shown that structural robustness can be better enhanced with double-type hangers than with single-type hangers. Finally, several useful recommendations are proposed for concrete self-anchored suspension bridges to improve structural safety and avoid progressive failure of hangers.