Effect of cracking, corrosion and repair on the frequency response of simply-supported reinforced concrete beams

Abstract

Premature deterioration of reinforced concrete (RC) structures due to structural loading and corrosion represents significant problem worldwide. Consequently, various system identification (SI) techniques have been developed to monitor the health and detect damage in structures where natural frequency is often used as a diagnostic parameter. This study consists of a laboratory investigation to investigate the effect of cracking, corrosion and repair on the frequency response of two series of simply-supported RC beams, namely ordinary Portland cement concrete (OPC) and functionally-graded concrete (FGC) beams. Significant changes in the frequency ratio, Rf, of the beams were observed; with a decrease in Rf associated with load-induced cracking, an increase in Rf associated with moderate reinforcement corrosion and a subsequent decrease in Rf associated with repair. The experimental results revealed that the frequency response can be used to infer the state of the health of the monitored structure by taking into account environmental conditions, likelihood of corrosion occurrence, properties of repair material and interfacial bonding.