Influence Of The Closure Order Of Prestressed Concrete Continuous Girder Bridge With Super-long Unit On Structural Effect

With the vigorous development of China's transportation industry,the bridge design theory and construction technology have become increasingly mature,and the prestressed concrete continuous girder bridges are gradually developing in the direction of the long span.At present,there are many studies on the design and construction of multi-span continuous girder bridges in China,but the research on super-long joint prestressed concrete continuous girder bridges is still relatively small.With the increase of the number of continuous beams,new problems will gradually be exposed.Based on the engineering background of a highway Huanghe Bridge,this thesis studies the closing scheme of the prestressed concrete continuous girder bridge with super-long unit,and proposes five different closing schemes.The finite element method is used to calculate and analyze the stress,deflection,bearing displacement and shrinkage and creep effects of bridges.The advantages and disadvantages of each closing scheme and the scope and applicable conditions of different closing schemes are proposed to provide reference for similar bridge projects.The main research contents are as follows:1.By consulting for relevant literature and data,the closure construction technology of continuous girder bridge at home and abroad and the closure sequence of continuous girder bridges are summarized.Several key factors affecting the closure of continuous girder bridges are analyzed.2.Based on the super-long unit prestressed concrete continuous girder bridge of the Huanghe Bridge(55m+12×100m+55m),combined with the relevant literature and data,five different closure plans are proposed.The Midas finite element models are established to calculate and analyze the effects of five different closure plans on the bridge shape,section stress and bearing displacement of the ultra-long joint structure.3.Referring to the relevant data,this thesis summarizes the relevant theories of concrete shrinkage and creep effects,and calculates the vertical displacement,bearing offset and cross-section stress caused by shrinkage and creep in 1 year,3 years,5 years and 10 years for five different closure plans respectively,and analyses and compares the shrinkage and creep effects caused by different closure plans in their respective operation periods.4.The variation rules of super-long unit structure under five different closing methods are summarized,and the advantages and disadvantages of each closing method are analyzed.The different scopes and applicable conditions are proposed,which provide reference for similar projects in the future.