Key Technology Research Of Long-span Prestressed Concrete Continous Girder Bridge In High-speed Railway

Taking (75 + 125 + 75) m prestressed concrete continuous girder bridge of Huning inter-city high-speed railway as the background , this paper has studied that the later creep controlled and the construction method that side-span didn't set closure segment from the view of design .Main work done as follows:(1) On the span prestressed concrete continuous girder bridge cross-sectional forms of qualitative analysis choice,it has studied forceanalysis accoding different mid-span and mid-span bearing beam high ,and determined reasonable beam high and structure stiffness to meet the requirements of the use function of (75 + 125 + 75) m prestressed concrete continuous girder bridge of high speed railway.(2) According analyzed influence factors of later creep deformation of large-span prestressed concrete continuous girder bridge, some related control later creep deformation measures were proposed. Results show that increasing beam high, adjustment of bottom slab and top deck tendon in side-span and midspan continuous girder bridge, extension concrete curing ages and 60 days load time of secondary dead load after closure can effectively control continuous girder bridge later creep.(3) Considering the time limit and economy, the construction method that cast-in-situ side-span beam section and cantilever segment is not set up the closed segment is widely applied. But the construction method has greatly affected by temperature changes, and the structure appears easily crack in joint for deflection changes that made by temperature change. In order to understand the function of temperature effect on the construction method, it has analyzed deflection and stress distribution of cantilever segment in nonlinear temperature effect, and studied some specific method that can effectively eliminate temperature effect, then verified the feasibility of construction method that side-span does not set closure segmen.