To investigate the long-term performance of a 32 m prestressed simply supported box girder,a 1:4 scale prestressed concrete simple supported box girder was cast.The casting procedure adheres to the principle of stress...To investigate the long-term performance of a 32 m prestressed simply supported box girder,a 1:4 scale prestressed concrete simple supported box girder was cast.The casting procedure adheres to the principle of stress equivalence within the concrete in the middle span after tensioning of prestressed tendons.Utilizing the CEB-FIP 90 model as a foundation,we established a long-term deformation calculation model for the box girder.Subsequently,the reliability of the long-term deformation model was confirmed by employing data from a 96 d long-term deformation test conducted on the box girder.Meanwhile,a new database was created by integrating shrinkage and creep experiment data with the shrinkage and creep database developed by Bazant.The shrinkage and creep uncertainty coefficients were introduced to complete the modeling of concrete shrinkage creep uncertainty calculations.The results demonstrate that the long-term deformation prediction model can effectively characterize the tendency of the mid-span upward deflection in the box girder.At 988 d,the upward deflection at the mid-span of the 1:4 scale model was expected to reach approximately 3.67 mm.It is worth noting that the CEB-FIP 90 model tends to slightly overestimate long-term deformation compared with experimental results.Additionally,it significantly underestimates the shrinkage strain observed in the test results.The uncertainty associated with the long-term deformation prediction of the structural system increased as the prediction time extended.展开更多
基金funded by the National Natural Science Foundation of China(Grant Nos.52178182,52108262,and U1934217)Science and Technology Research and Development Program Project of China Railway Group Limited(Major special project,Nos.2020-Special-02,2021-Special-08,2022-Special-09,and 2023-Major projects-07,Major project,No.2021-Special-02,Key project,Nos.2021-Key-11,and 2022-Key-46)+1 种基金the Natural Science Foundation for Distinguished Young Scholars of Hunan Province(No.2022JJ10075)Hunan Science and Technology Plan Project(No.2023SK2014).
文摘To investigate the long-term performance of a 32 m prestressed simply supported box girder,a 1:4 scale prestressed concrete simple supported box girder was cast.The casting procedure adheres to the principle of stress equivalence within the concrete in the middle span after tensioning of prestressed tendons.Utilizing the CEB-FIP 90 model as a foundation,we established a long-term deformation calculation model for the box girder.Subsequently,the reliability of the long-term deformation model was confirmed by employing data from a 96 d long-term deformation test conducted on the box girder.Meanwhile,a new database was created by integrating shrinkage and creep experiment data with the shrinkage and creep database developed by Bazant.The shrinkage and creep uncertainty coefficients were introduced to complete the modeling of concrete shrinkage creep uncertainty calculations.The results demonstrate that the long-term deformation prediction model can effectively characterize the tendency of the mid-span upward deflection in the box girder.At 988 d,the upward deflection at the mid-span of the 1:4 scale model was expected to reach approximately 3.67 mm.It is worth noting that the CEB-FIP 90 model tends to slightly overestimate long-term deformation compared with experimental results.Additionally,it significantly underestimates the shrinkage strain observed in the test results.The uncertainty associated with the long-term deformation prediction of the structural system increased as the prediction time extended.
