Long-term performance of prestressed concrete bridges under the intertwined effects of concrete damage, static creep and traffic-induced cyclic creep

The current progress towards sustainable transportation demands for a prolonged lifespan, i.e., over 100 years, for large-span bridges. To accomplish this goal, realistic prediction of the long-term performance of bridges plays an indispensable role in bridge engineering. In this study, the long-term deflection and the deflection-induced damage growth are investigated for the large-span prestressed concrete bridges carrying busy traffic flows. A unified constitutive model, taking into account the coupled effects of concrete viscoelastic behavior and concrete tensile cracking and plastic softening, is developed to estimate the bridge performance. Here the static creep of concrete is approximated by a series of Kelvin units. The elasto-plastic damage of concrete is described by the plasticity yield surfaces hinging on the flow rules and anisotropic damage laws anchored at the strain equivalence hypothesis. In addition to the static creep, the cyclic creep of concrete induced by vehicles is integrated in the nonlinear stress-strain incremental relation based on the fatigue growth of microcracks. With the aid of the 3D rate-type formulation, the proposed unified model is implemented in ABAQUS and a large-span prestressed concrete bridge carrying heavy traffic loads is analyzed. Compared to the inspection reports, the deflection history at the midspan, the deformed profile of the whole bridge and the distribution of concrete cracking are all adequately captured in the simulations. Further sensitivity investigation on bridge deflection finds that the cyclic load-induced damage accumulation process plays a non-negligible role and traffic management plans are needed for heavy trucks to mitigate the risk of excessive deflection and concrete degradation.