###### Abstract
It has only been reported that rebar corrosion is the main cause of RC member degradation and reduces the bonding performance [11; 12; 13; 14; 15; 16; 17; 18; 19]. From the previous, it follows that the seismic performance of RC structures with corrosion-damaged members should be quantitatively and directly evaluated using the structural performance degradation coefficient based on the strength-deformation capacity, i.e., the energy dissipation capacity. Based on these research results, it may be possible to evaluate more accurately the seismic performance of RC structures with corroded members including beams and columns. Therefore, the main purpose of this study is to propose a practical methodology to evaluate the seismic performance of RC structures with corrosion-damaged members; that is, a direct quantitative evaluation of their seismic performance by estimating factors for structural performance degradation based on the strength and deformability of corrosion-damaged members. In pursuit of the above background and the purpose of the study, we first performed an experimental study to estimate the impact of reinforcement corrosion on the structural behavior of RC beams and determine the factors of structural performance degradation; these results have already been published [1]. The published paper describes the experimental process and results of the impact of rebar corrosion on the structural behavior of RC beams, i.e., the structural performance degradation factor as a function of rebar-corroded RC members experimentally tested using four-point loading under simply supported conditions. In the structural test, shear and flexural beams (\(n=8\) each) were fabricated, and the impact of reinforcement corrosion on shear and flexural failure was tested. The current technique was used to accelerate the reinforcement corrosion of shear and vertical rebars. A half-cell potential (HCP) was used to quantify the corrosion potential of rebar. Lastly, the correlation between the structural performance degradation factor of the corrosion-damaged member and the voltage-based average potential difference for shear and flexural behavior was proposed, as plotted in Figure 4. \begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**Element**} & \multirow{2}{*}{**Range**} & \multicolumn{2}{c}{**Deterioration and Aging**} \\ \cline{3-4}  & & **1.** & **Cracking by Concrete Expansion Due to the Rust of Reinforcing Bar** \\  & & **2.** & **Rust of Reinforcing Bar** \\  & & **3.** & **Deterioration of Concrete Caused by Chemicals** \\ \hline \multirow{4}{*}{Slab including sub-beam} & 1/3 or more & & 0.017 \\ \cline{2-4}  & 1/3–1/9 & & 0.006 \\ \cline{2-4}  & 1/9 or less & & 0.0023 \\ \cline{2-4}  & 0 & & 0 \\ \hline \multirow{4}{*}{Beam} & 1/3 or more & & 0.05 \\ \cline{2-4}  & 1/3–1/9 & & 0.017 \\ \cline{2-4}  & 1/9 or less & & 0.006 \\ \cline{2-4}  & 0 & & 0 \\ \hline \multirow{4}{*}{Wall \& Column} & 1/3 or more & 0.15 \\ \cline{2-4}  & 1/3–1/9 & & 0.05 \\ \cline{1-1} \cline{2-4}  & 1/9 or less & & 0.017 \\ \cline{1-1} \cline{2-4}  & 0 & & 0 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Evaluation of \(T\) value. As shown in Figure 4, our aforementioned prior research revealed a relatively high correlation between the performance degradation factor of corroded beam members and the average potential difference in voltage; that is, the correlation coefficient (R\({}^{2}\)) of the flexural beam and shear beam was verified as 0.78 and 0.91, respectively. It also revealed that the potential difference measured by the HCP method can also be used as an indicator of relative structural performance reduction under constant environmental conditions, and the energy absorption capacity, proposed based on the strength-deformation capacity of corroded RC members, can be evaluated based on the correlation between the performance degradation factor and the average potential difference.