It is often the case that a large a

It is often the case that a large amount of reinforced concrete (RC) structures such as highway or railway bridges are damaged because of the corrosion of the steel rebar. It has been a hotspot in the structural rehabilitation to conduct degradation evaluation of the mechanical behavior of the existing reinforced concrete structures by corrosion. The primary causes can be roughly categorized into: (1) the reduction of the effective diameter of reinforcement bars; (2) the loss of bond between steels; (3) the concrete and the micro cracking of the concrete due to the expansion of the bars by the rust products as a consequence of electrochemical processes (Rteil, Soudki, and Topper, 2007). From the literature review, it can be figured out that compared with the sound beam; the behavior of RC structures deteriorated by the reinforcement corrosion has its own distinction. Specifically, the conventional concrete has a pore solution with high alkalinity which forms a passive layer around the steel and prevents from corrosion. However, because of the poor concrete quality, the inadequate thickness of the concrete cover, the imperfect workmanship and the constructional characteristic under extreme environmental conditions, the passivation effect of the concrete pore solution can be neutralized (Baweja, Roper, and Sirivivatnanon, 1998). It is well known that corrosion by-products will induce volumetric