Load relief during structural repairs to reinforced concrete beams

Corrosion of reinforcement is the main cause of deterioration of structural concrete. In some instances, loss of reinforcement section requires provision of additional or replacement bars. This Paper presents results from an analytical and experimental study to determine whether or not it is necessary to relieve load from a beam while replacement reinforcement is installed. The results show that the ultimate strength of a beam is not adversely affected by omission of load relief, provided that a reasonable margin of safety is maintained while the beam is in a weakened state during repair, although there may be a slight loss of ductility with more heavily reinforced sections. Serviceability performance is affected by omission of load relief, i.e. some aspects of behaviour improve while others worsen. An unexpected mode of failure was recorded in a pair of repaired beams in the experimental work, which illustrates the difficulties inherent in applying the requirements of codes of practice intended for new construction to repair situations.