# Effect of Corrosion on the Hysteretic Behavior of Steel Reinforcing Bars and Corroded RC Columns
## 3 Experimental Results and Discussion  
### Corrosion Damage of Steel Reinforcing Bars  
The results of the accelerated corrosion procedure are summarized in Table 2. In order to quantify the corrosion damage of steel bars in a uniform way, the mass loss and the mean reduced diameter, d\({}_{\text{red}}\), of each steel bar were calculated by Equations (1) and (2). However, several embedded (in concrete) steel bars demonstrated uneven corrosion damage along their length and circumference, since the aggressive corrosive factors were diffused and acted mainly in areas of concrete with a high porosity or in areas of the concrete cover with defects or cracks. Due to this fact, large pits and the localized loss of their initial cross-section were observed locally on the embedded corroded steel bars. In order to estimate the actual local damage, the effective diameter d\({}_{\text{eff}}\) of corroded steel bars was measured using a digital Vernier in the critically reduced cross sections. Representative figures of the localized corrosion damage are given in Figure 7 and uniform corrosion is depicted in Figure 8.  
Figure 6: Corrosion penetration depth (x) and mean reduced cross-section considering uniform corrosion around the steel bar’s circumference. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Steel Bar** & **Mass Loss (\%)** & \(\mathbf{d_{0}}\) & \(\mathbf{d_{red}}\) & \(\mathbf{d_{eff}}\) & **Corrosion Damage** \\ \hline X1 & 0 & 16 & - & - & Non-corroded \\ X2 & 0 & 16 & - & - & Non-corroded \\ X3 & 0 & 16 & - & - & Non-corroded \\ X4 & 0 & 16 & - & - & Non-corroded \\ X5 & 0 & 16 & - & - & Non-corroded \\
11 & 1.95 & 16 & 15.84 & 15.84 & Uniform corrosion \\
36 & 2.46 & 16 & 15.80 & 15.80 & Uniform corrosion \\
9 & 3.34 & 16 & 15.73 & 15.73 & Uniform corrosion \\
25 & 3.39 & 16 & 15.73 & 15.73 & Uniform corrosion \\
24 & 3.54 & 16 & 15.71 & 15.71 & Uniform corrosion \\
22 & 3.8 & 16 & 15.69 & 15.69 & Uniform corrosion \\
37 & 3.93 & 16 & 15.68 & 15.68 & Uniform corrosion \\
21 & 4.18 & 16 & 15.66 & 15.66 & Uniform corrosion \\
13 & 4.92 & 16 & 15.60 & 15.60 & Uniform corrosion \\
6 & 5.27 & 16 & 15.57 & 15.57 & Uniform corrosion \\
34 & 5.59 & 16 & 15.55 & 15.55 & Uniform corrosion \\
3 & 5.85 & 16 & 15.52 & 13.61 & Fitting corrosion \\
12 & 5.95 & 16 & 15.52 & 15.52 & Uniform corrosion \\
15 & 6.09 & 16 & 15.51 & 13.80 & Fitting corrosion \\
29 & 6.22 & 16 & 15.49 & 10.50 & Fitting corrosion \\
19 & 6.65 & 16 & 15.46 & 15.46 & Uniform corrosion \\
7 & 6.75 & 16 & 15.45 & 10.60 & Fitting corrosion \\
10 & 6.97 & 16 & 15.43 & 14.00 & Fitting corrosion \\
23 & 7.11 & 16 & 15.42 & 15.42 & Uniform corrosion \\
20 & 7.13 & 16 & 15.42 & 13.00 & Fitting corrosion \\
28 & 7.17 & 16 & 15.42 & 12.30 & Fitting corrosion \\
30 & 8.35 & 16 & 15.32 & 15.32 & Uniform corrosion \\
48 & 9.45 & 16 & 15.22 & 15.22 & Uniform corrosion \\
18 & 10.69 & 16 & 15.12 & 12.10 & Fitting corrosion \\
14 & 10.95 & 16 & 15.10 & 13.80 & Fitting corrosion \\
2 & 11.33 & 16 & 15.07 & 8.00 & Fitting corrosion \\
26 & 11.37 & 16 & 15.06 & 11.90 & Fitting corrosion \\
1 & 11.65 & 16 & 15.04 & 11.70 & Fitting corrosion \\
8 & 14.82 & 16 & 14.77 & 11.30 & Fitting corrosion \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Results of the accelerated corrosion tests on the embedded steel reinforcing bars. Figure 7: Areas (red dots) of pitting corrosion of steel reinforcing bars: (**a**) localized reduction in the cross-section; (**b**) pits on the surface of the corroded steel bar. As can been observed from Table 2, for low levels of corrosion damage up to 6% mass loss, the type of steel corrosion was characterized as uniform with a corresponding percentage reduction in the nominal diameter of steel bars up to 3.0% (from d0 = 16 mm to dred = 15.52 mm) and of the cross-section up to 5.9%. In that case, as has been indicated in previous studies [28; 29], corrosion leads to a slight reduction in the mechanical properties of steel bars, but also leads to significant degradation on the local conditions of steel-concrete bond mechanism.