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Full Program » Accurate prediction of the long-term deformation of prestressed concrete box girders is of significant importance for bridge safety and serviceability. Despite the great progress made in implementing rate-type analysis based on rheological models in creep structural analysis, constitutive laws coupling concrete time-dependent mechanics with damage are limited in predicting the long-term deformation of prestressed large-span bridges. This study is aimed at providing a systematic approach for the structural analysis of prestressed concrete, which is undergoing a strong coupling of time-dependent behavior and elasto-plastic damage during its lifetime. In this study, a rheological model residing on Kelvin chains is coupled with a plastic-fracture unit in a series pattern to realistically capture the interaction of concrete creep and shrinkage with cracking. The plastic-fracture unit, prescribed with a plasticity yield criterion with flow rule and anisotropic damage evolution based on the strain equivalent hypothesis, is employed to simulate the time-independent behaviors of concrete. Here the stiffness recovery due to cracking opening and closing is taken into account in the model. The coupling of Kelvin chains with the plastic-fracture unit is realized by an implicit algorithm using returning mapping and Newton-Raphson iteration. With the aid of continuous spectrum method and exponential algorithm, the computational cost can be significant reduced for large structural creep analysis. To illustrate the effectiveness of this unified constitutive law, a case study based on a real prestressed large-span bridge is demonstrated. In addition to static creep and concrete damage, cyclic creep due to the heavy traffic on this bridge is also considered in the investigation.

Author(s):

Teng Tong
University of Pittsburgh
United States

Weijin Wang
University of Pittsburgh
United States

Qiang Yu
University of Pittsburgh
United States