Analysis Of Creep Deflection In Large-span Continuous Rigid Frame Bridge

It is a common phenomenon that deflection occurs across the middle of large-span, prestressed, continuous concrete rigid frame bridge. At present,as the running time of bridge increases, the deflection across the middle has a long-term growth, which is difficult to converge. The actual deflection value of the structure is much greater than the design value. Among many reasons that result in deflection across the middle of bridge, the effect of concrete creep, due to the complexity of its calculation, the variety of affecting factors, few reports were presented. Since in most of the structure calculations only two-dimensional bar finite element model was used, it is significant to investigate how to take the spatial effect of concrete creep into account in commercial finite element software analysis.Firstly, this paper reviews the domestic and international long-span continuous rigid frame bridge problems, presents the calculation theories of concrete creep and calculation models at home and abroad, and makes a comparative analysis of the calculation models. The auxiliary channel bridge of Humen Bridge, a large-span continuous rigid frame bridge is modeled and calculated as a finite element model in MIDAS/Civil. Creep effect on deflection across the bridge middle, the role of creep, prestress loss and beam crack interaction are then discussed.Finally, creep analysis of a solid model of prestressed concrete beam is implemented in the finite element software ABAQUS. Based on Zhu Bofang's theoretical creep formula, creep effect on mid-span deflection is coded with FORTRAN in the user subroutine UMAT in ABAQUS. Creep model involves a lot of parameters. Since there are no experiments to determine material parameters, only reversible creep is considered in this paper.