Creep And Shrinkage Effect On Curved Prestressed Concrete Box Girders

Current studies on curved girders are mainly about the elastic and inelastic behavior, the studies on creep and shrinkage effect of curved girders are rare. By finite element method, creep and shrinkage effect on curved concrete box girders were studied in detail.An overview on the existing literature, several hypotheses of creep and shrinkage principle was summarized. The parameters affecting concrete creep and shrinkage were discussed. The classical theories for calculating creep and shrinkage effects were introduced briefly, and its prerequisite, merits and drawbacks, applicability were analyzed. The modern theories for calculating creep effect were introduced. Four creep and shrinkage prediction models were presented, and their principle, parameters and applicability were discussed.The principle and application of single beam method and grillage method were introduced, especially the application of grillage method. Based on the traditional grillage method, the improved grillage method (IGM) was established. The accuracy of IMG model was verified by comparing the linear elastic results of models using different discrete method.Based on the CEB-FIP(1990)prediction model, the single beam model and IMG model were established using LUSAS Bridge? to analyzed the creep and shrinkage effect of a curved girder , some available conclusions were attained. The different creep and shrinkage effect of different mid-support condition were studied. The results showed that using hinged bearing is superior to set torsion restraint bearing at the middle support.Considering the construction process to construct the finite element model, the creep and shrinkage effect of curved girder were analyzed. It was proved that the creep and shrinkage of concrete is favorable for the curved girder behavior at a certain extent.The parameters analysis on the creep and shrinkage effects of curved girder was conducted by transforming the radius of curvature. The results indicate the deformation of curved girder is increasing along with the increase of central angle and the gradient increased gradually, the mid-span section's normal stress redistribution of short radius of curvature model is fast relative.At last, long-term creep and shrinkage effect of ramp E, a curved prestressed concrete box girder bridge, which is part of a interchange was analyzed.