Bond behaviour between corroded steel bars and concrete under different strain rates

The impressed current method was used to produce 42 corroded reinforced concrete specimens. Pull-out tests were conducted to study the effects of strain rate, corrosion degree, concrete cover and stirrups on the bond behaviour between corroded rebars and concrete. The results showed that the lag effect of radial cracking in concrete will occur with increasing strain rate. The failure modes of the specimens changed from splitting of the concrete cover to pull-out failure of rebars, and the bond strength of the splitting specimens increased significantly as the rebars were loaded at a higher rate. The bond strength of corroded specimens decreased with the development of reinforcement corrosion under both static and dynamic loading. Coupling effects of corrosion degree and strain rate on bond strength were found. The degradation trend caused by corrosion decreased with increasing strain rate, and the effect of strain rate on the ultimate bond strength also decreased with an increasing degree of corrosion. In addition, specimens with smaller diameter rebars, a thicker concrete cover and stronger stirrups exhibited higher bond strength. Considering the effects of strain rate and corrosion, a model is proposed to predict the bond behaviour between corroded rebars and concrete under different strain rates.