Experimental investigation on the dynamic properties of RC structures affected by the reinforcement corrosion

Reinforcement concrete (RC) structures in service are suffered from environmental attacks, especially the rebar corrosion, which may lead to the deterioration of mechanical characteristics of steel bars, surrounding concrete and bond strength, and therefore jeopardize their performance in earthquake events. In this paper, an electro-chemical accelerated corrosion process was introduced to RC frames and columns, and then the half-cell method, linear polarization method and constant potential step method were performed to monitor the corrosion status. Furthermore, for studying the dynamic properties of RC structures affected by reinforcement corrosion, the dynamic tests were carried out to study the fundamental frequency and damping ratio of control frame and frames which designed steel losses were 10% and 30%, respectively. The experimental results show that the influence of corrosion damage on fundamental frequency and damping ratio is significant. Substantial increases were observed in fundamental frequency and damping ratio after the accelerated corrosion occurred. It indicates that the decreased bond strength or ultimate bearing capacity cannot ensure that the stiffness of healthy member is always greater than that of damaged member. Moreover, the variations of frequency and damping ratio, induced by steel corrosion, are not inconsistent. This investigation provides further insight into the use of fundamental frequency and damping ratio to detect damage of RC structures.