The Shrinkage And Creep Analysis Of The Large-span Prestressed Concrete Continuous Box Girder Bridge

The shrinkage and creep of prestressed concrete continuous girder have hugeeffects on the internal forces and deformation of structure. Because of the complexmechanism of concrete shrinkage and creep and a great many influenced factors whichare mostly random, the analysis of shrinkage and creep on the structural properties isdifficult to find the accurate answers. The way to accurately predict and control theeffect of concrete shrinkage and creep is a pressing problem which is needed to besolved in the actual project.This paper, supported by the past research findings, with engineering back groundof the continuous girder renovation project with the main span of125m located inJiangsu province, studies the effects of shrinkage and creep on the large-spancontinuous prestressed concrete box girder bridge in the construction and operationalphase. The main works and relevant conclusions are as follows:①The effect of concrete shrinkage and creep on the stress of continuous beam:By establishing a finite element model of the beam element for the full-bridge,combining with the commonly used specifications and the construction monitoring data,the paper analyses the effects of shrinkage and creep on the stress of the main bridge.The conclusion is that because of shrinkage and creep, the upper edge of the stress ofthe most continuous beam cross-sections will decrease and the lower edge of the stressof the most continuous beam cross-sections will increase.②The effect of concrete shrinkage and creep on the deflection of continuousbeam: By establishing a finite element model of the beam element for the full-bridge,combining with the commonly used specifications and the construction monitoring data,the paper analyses the effects of shrinkage and creep on the deflection of the mainbridge. The conclusion is that because of shrinkage and creep, the deflection of thebeam will decline with varying degrees. So, it must be considered in designing andconstruction controlling.③The comparative study of different shrinkage and creep models: Combinedwith the construction monitoring data, the paper makes a comparative study of the stressand deflection of the main bridge which is established in different kinds of shrinkageand creep models. The conclusion is that the model of shrinkage and creep ofCEB-FIP(1990) is more suitable for analyzing the shrinkage and creep of the large-span prestressed concrete continuous beam.④The analysis of concrete shrinkage and creep based on the local solid elementsmodel: For analyzing the most complex forced beam segments neared the piers, thepaper establishes a finite element model of the solid elements and analyses the stresseffect of shrinkage and creep on the box girder cross-section. The conclusion is thatbecause of shrinkage and creep, the webs and flanges of the box girder have a largercompressive stress which should be considered in designing and constructioncontrolling.