Study On Long-term Deformation Of Long-span Rigid Frame Bridges With High Piers

Shrinkage and creep are the inherent time-dependent characters of concrete whichbelongs to a viscoelastic materal. It is important to accuratelly estimate and predicatethe stress and deflection of long-span bridges with high piers which arise from the effectof shrinkage and creep for engineering design, quality control and construction process.Long-span continuous rigid bridges with high piers are sensitive to shrinkage andcreep. Lack of shrinkage and creep prediction will directly affect the construction andsubsequent operation of the bridge. This type bridge majorly use the concrete with highstrength and high performation. Compared to ordinary concrete, this concrete has a lowwater-cement ratio, high density and other characteristics. The research also shows thatthe forecasting model based on ordinary concrete shrinkage creep can not be directlyused for high performance concrete. The main research of this content are:①On the basis of extensive collection of domestic and foreign shrinkage ofconcrete creep research data, discuss the concrete creep mechanism depthly. Divide thefactors influencing the shrinkage and creep of concret into internal and external factors,and discuss it. Focusing on the domestic and foreign common shrinkage and creepprediction model in the discussion, and use B3coefficient of variation to calculate theaccuracy of these models.②Using the same and mix proportion of concrete as Bridge Niujiaoping, and dothe shrinkage and creep test at constant temperature and humidity test chamber. On thebasis of the analysis of the test results, select the Dirichlet series and use the MATLABto obtain the proposed model for the type of this concrete Compare the calculation ofthe proposed model, ACI209R (1992) model, CEB-FIP series modelsadn GL2000model, discuss the result one by one.③Considering shrinkage and creep and its influencing factors are randomvariables, use the stochastic finite element theory to calculate the long-term deflectionof Niujiaoping Bridge. Introduce the response surface which belongs to stochastic finiteelement into the long-term deflection of structure, and use the approximate fittingresponse surface to replace the actual surface, and use the Monte Carlo method to do thenumerical experiments to obtain the certain confidence intervals within the structure oflong-term deformation value.④In this paper, observe the deformation of Niujiaoping Bridge by two years, Use response surface methodology and certainty analysis methods for the calculation oflong-term deformation in the bridge to bridge, compare and analyze the calculatedresults and the test results.