Effects of the position and chloride-induced corrosion of strand on bonding behavior between the steel strand and concrete

Degradation of bonding behavior due to chloride-induced corrosion of steel strands is critical for serviceability of prestressed concrete structures. In this paper, total thirty-one central and eccentric pull-out specimens were tested to study the effects of strand corrosion, combined with stirrups or position of steel strand on global forceslip response, bond strength and failure pattern. Experimental results show that the bond strength of the eccentric pull-out specimen without corrosion or slight corrosion is greater than that of the centrally loading ones, and the opposite is true once the corrosion rate reaches 6%. Stirrups in bonding specimens can effectively restrain the transverse deformation of concrete, and significantly improve the bond strength between corroded strand and concrete. As the corrosion rate of steel strand increases, the bond-slip curves of specimens with stirrups tend to be similar to those without stirrups. Compared with the corroded deformed bar, the degradation of bond behavior caused by deformed bar corrosion is more serious than that of steel strand corrosion. By considering the combined effects of steel strand corrosion, stirrups and position of steel strand, an empirical model is proposed to predict the bond strength between corroded steel strand and concrete with reasonable accuracy.