Analysis of repaired reinforced concrete structures

A procedure is described by which nonlinear finite-element algorithms can b e modified to enable the analysis of repaired or rehabilitated concrete str uctures, taking into account the chronology of the loading, damage, and rep air. The method defines and employs plastic strain offsets in the context o f a smeared rotating crack model. The ability to engage and disengage eleme nts at various stages of loading, as well as the ability to carry forward s train 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 acc ounting for changes in strength, stiffness, ductility, and failure mode as a result of strengthening measures. Flexure-dominated and shear-dominated r esponses are equally well represented. The analysis of a repaired shear wal l, subjected to reversed cyclic lends, illustrates the ability to model sev erely damaged structures where some portions must be removed and reconstruc ted. In all cases, the analysis procedure was numerically stable and effici ent at all stages of loading.