A finite element model to simulate long-term behavior of prestressed concrete girders

The development of a finite element model for time-dependent analysis of bonded prestressed concrete girders at service conditions is presented. The effects of creep and shrinkage of concrete and relaxation of steel tendons are taken into account. The concrete creep is modeled based on the Dirichlet series creep compliance with efficiency in simulating the stress history. In addition, the interaction between different time-dependent effects is fully considered in the numerical procedure. The numerical method is formulated based on the layered Euler–Bernoulli beam theory. In the constructed incremental equilibrium equations, the equivalent nodal load increments consist of four components contributed by external loads, concrete creep, concrete shrinkage and tendon relaxation, while the stiffness matrix is composed of the material and geometric stiffness matrices. Numerical examples show that the proposed model can well predict the long-term behavior of prestressed concrete beams, and that the time-dependent effects have important influence on the structural behavior.