Abstract:The ultra-long multi-span prestressed continuous girder bridge with more than 5 spans and a combined length of more than 600 m is increasingly used in highway bridges because of its advantages such as high overall stiffness, good driving comfort and low vehicle-induced vibration. However, in the construction process, it will experience the system conversion caused by multiple closures, and the construction period is long, which has to experience the influence of temperature, creep and contraction. As a result, it is difficult to accurately calculate the longitudinal displacement of the support. Setting a reasonable predeflection for it becomes a problem of key technologies during construction. Therefore, taking the predeflection setting of supports for a 21-span continuous ultra-long prestressed girder bridge as a research example, by comprehensively considering the influencing factors of temperature, shrinkage creep and prestress addition, a full-bridge finite element model is established to analyze the difference in the predeflection setting of supports with two closure schemes "from the middle to both sides" and "from both sides to the middle”. Based on the force-displacement function, the influence of friction in the sliding process of the supports on the support displacement is calculated, which realizes the accurate computational analysis and effective control of longitudinal displacement of the girders during the construction.
