Composite Unit-Based Evaluation of the Creep Effects of Continuous Prestressed Concrete Box Girders

Abstract

To evaluate the influence of concrete creep effect on spatial stress in concrete, the formulas for recursive calculation of equivalent nodal loads of concrete creep of PC composite unit under multi-axial stress was considered. The formulas are extended to general cases, and then an FEM program for calculating concrete creep is developed. A typical continuous PC bridge is illustrated to analyze the regular pattern of structural creep behavior. The differences in creep calculation modes using different codes and variation characteristic of main girder deflection are found. The service stage characteristics of a PC box girder are evaluated to determine the redistribution of longitudinal normal stress at the top, bottom, and principal stress at the web. Finally, recommendations for the reasonable arrangement of prestressed tendons are provided.