Analysis of repaired reinforced concrete structures

A procedure is described by which nonlinear finite-element algorithms can be modified to enable the analysis of repaired or rehabilitated concrete structures, taking into account the chronology of the loading, damage, and repair. The method defines and employs plastic strain offsets in the context of a smeared rotating crack model. The ability to engage and disengage elements at various stages of loading, as well as the ability to carry forward strain measures representing previous loading and damage conditions, are key aspects in the analysis method. Analysis of beams and slabs repaired with fiber-reinforced plastics demonstrates the accuracy of the procedure in accounting for changes in strength, stiffness, ductility, and failure mode as a result of strengthening measures. Flexure-dominated and shear-dominated responses are equally well represented. The analysis of a repaired shear wall, subjected to reversed cyclic lends, illustrates the ability to model severely damaged structures where some portions must be removed and reconstructed. In all cases, the analysis procedure was numerically stable and efficient at all stages of loading.