Effect Of Shrinkage And Creep On Deformation Of Continuous Rigid Frame Composite Girder Bridges With Stiffened Steel Truss

Along with the development of our social economy,transport infrastructure construction is in full swing,of all kinds of large span Bridges sprang up.Among them,the long-span concrete continuous rigid frame bridge because of its advantages of easy construction,economy,smoothly driving comfort widely used.But in recent decades,the long-term deformation of a lot of big span prestressed concrete bridge due to creep and shrinkage problem increasingly prominent,which has been built a number of good bridge safety,durability problems.To control the influence of shrinkage and creep deformation of the bridge,this paper studies the mechanism of concrete creep and shrinkage,summaries all kinds of commonly used forecasting mode for the shrinkage and creep,shrinkage and creep are analyzed on the influence of the prestressed concrete continuous rigid frame bridge,takes Mogu River 2# reinforced steel truss continuous rigid-framed bridge as the research background,for all kinds of creep and shrinkage prediction model calculation results are analyzed,comparing its displacement of completion moment and the moment of ten years later,comparing the differences between all kinds of creep and shrinkage prediction model;analyzed the influence factors of creep and shrinkage(relative humidity,prestress loss and overall stiffness),compares the above a few kinds factors on the degree of shrinkage and creep effect size.The analysis results show that the shrinkage and creep impact factor weights order from large to small is: relative humidity,loading age,thickness of components,air content,water cement ratio,aggregate content;CEB-FIP prediction model and the prediction model for code early changing rate of creep coefficient is bigger and the late changing rate is smaller.ACI-209 model not considering lag elastic strain,BP series model considering the matching ratio on the shrinkage and creep,and more consistent with the actual;Relative humidity,loss of prestress,the overall stiffness factor to four types of different degree of influence on the shrinkage and creep,and thus cause the change of the creep deformation.