Permanent deformation limits of long-span track cable-stayed bridges based on service performance analysis

With the continuous service time, long-span track cable-stayed bridges are inevitably affected by material time-varying and fatigue load periodic effects, and permanent down-deflection phenomenon is inevitable. The down-deflection of the main girder would lead to the irregularity of bridge deck, which would directly affect the running comfort and safety of the train. The permanent deformation control value should be set reasonably. In this paper, based on the research and analysis of domestic and foreign codes and standards, the evaluation criteria for the service performance of long-span track cable-stayed bridges was determined, aiming at the problem of deformation classification control in the service stage of the long-span track cable-stayed bridge. The limit of permanent deformation of main girder was analyzed, and the decision processing was put forward and applied to an engineering example. According to the vehicle-bridge coupling vibration analysis, the maximum vertical deformation safety control value in the service stage is L/400, and the pre-warning control value is L/500. With the non-permanent deformation value β deducted, the permanent deformation safety control value is L/400-β, and the pre-warning control value is L/500-β. The rationality of the grading control limit of permanent deformation based on service performance analysis has been verified by application analysis.