EFFECT OF CORROSION ON BOND BETWEEN REINFORCING STEEL AND CONCRETE UNDER CYCLIC LOADING

Cyclic loading can result in severe degradation of bond between reinforcing steel bar and the surrounding concrete, especially when the reinforcement is corroded.Tests have been carried out to evaluate the effect of reinforcement corrosion on bond under cyclic loading for different corrosion levels.Parameters investigated include corrosion level and lateral confinement.The embedded reinforcing steel bars, either laterally confined or unconfined, were corroded to different levels by accelerated corrosion method before being tested for bond stress-slip under cyclic loads.The results revealed that a low level of corrosion helped to reduce bond loss during loading.However, this effect was decreased as corrosion level increased.The bond capacity in unloading phase was only three-fourth of that in loading phase.Bond strength decreased more substantially as corrosion level increased in unconfined bars than in confined ones.The term bond degradation factor was developed to represent the bond loss during loading.A higher level of corrosion caused bond degradation primarily in the initial five loading cycles, the effect of corrosion being decreased with loading.It was also demonstrated that cyclic bond stress-slip curve depended on loading history.