Structural assessment of corroded reinforced concrete beams: Modeling guidelines

The evolution of the structural behavior in reinforced concrete beams subjected to reinforcement corrosion is studied here, by developing a suitable numerical procedure, which is validated by comparison with available test data. There are two objectives of this study: The understanding of the many aspects of the progressive damage in an existing structure (cracking and crushing, bar yielding, bond failure), and the assessment of the actual safety level. Nonlinear finite element analysis is used; the effects of corrosion are modeled by reducing the geometry of the finite elements representing separately the steel bars and the concrete, and by modifying the constitutive laws of the materials (steel and concrete) and of their interface (bond). Both the service and ultimate limit states are studied, showing the importance of the following phenomena: (1) Stiffness decay because of impaired tension stiffening, (2) crack pattern evolution accompanied by enhanced shear effects, (3) strength deterioration in bending and shear, (4) transition from tension to compression-triggered failures in critical sections, and (5) bond failure along the span and/or at beam ends. With reference to the last issue, the introduction of a specific model for bond deterioration appears to be of paramount importance in order to evaluate the residual ductility of a structure.