## 4 Results
### Corroded Specim
#### 4.2.1 Modelling Strategy 1  
It is worth reminding that in this strategy the constitutive laws of steel are reduced as a function of the loss mass, that was measured directly on the bars, following the experimental tests. The numerical results, compared with the experimental ones, are reported in Figure 13.  
The cyclic behaviour, characterized by pinching, is well-caught thanks to the bond reduction, which in the loading and unloading phase reduces the collaboration between steel and concrete. The latter aspect, however, in a modelling strategy that does not consider the variation of the section along the bar, leads to excessive slip of the bars with the consequent over-estimation of the yield drift. The crack patterns obtained through numerical simulations are in good agreement with the experimental observations, with the formation of base cracks that open and close during the cycles as shown below. This crack is precisely due to the bond losses and reinforcement sliding, which also reduces the energy dissipation.  
Figure 13: Comparison between experimental and numerical response, corroded specimens, MS 1. (**a**) column B25, (**b**) column B30.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multicolumn{2}{c}{**Specimen**} & \multicolumn{1}{c}{**Max. Load (+)**} & \multicolumn{1}{c}{**Drift at Max. Load (+)**} & \multicolumn{1}{c}{**\(\Delta\)Load (+)**} & \multicolumn{1}{c}{**Max. Load (-)**} & \multicolumn{1}{c}{**Drift at Max. Load (-)**} & \multicolumn{1}{c}{**\(\Delta\)Load (-)**} \\ \hline \multirow{4}{*}{B25} & Experimental & kN & \multicolumn{4}{c}{kN} & \multirow{4}{*}{\(-\)1.00\%} \\  & MS-1 & 40.85 & 1.17\% & & \(-\)7.07\% & \(-\)40.47 & \(-\)1.10\% \\ \cline{1-1}  & MS-2 & 38.58 & 1.10\% & \(-\)12.25\% & \(-\)36.20 & \(-\)1.03\% & \(-\)5.76\% \\ \cline{1-1}  & MS-3 & 42.99 & 1.00\% & \(-\)2.20\% & \(-\)37.39 & \(-\)0.011 & \(-\)2.68\% \\ \cline{1-1}  & MS-4 & 42.77 & 0.80\% & \(-\)2.70\% & \(-\)37.53 & \(-\)1.30\% & \(-\)2.32\% \\ \hline \hline \end{tabular}
\end{table}
Table 8: Main results of corroded specimens B25, experimental vs. numerical.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multicolumn{2}{c}{**Specimen**} & \multicolumn{1}{c}{**Max. Load (+)**} & \multicolumn{1}{c}{**Drift at Max. Load (+)**} & \multicolumn{1}{c}{**\(\Delta\)Load (+)**} & \multicolumn{1}{c}{**Max. Load (-)**} & \multicolumn{1}{c}{**Drift at Max. Load (-)**} & \multicolumn{1}{c}{**\(\Delta\)Load (-)**} \\ \hline \multirow{4}{*}{B30} & Experimental & kN & \multicolumn{4}{c}{kN} & \multirow{4}{*}{\(-\)1.00\%} \\  & MS-1 & 40.76 & 0.93\% & & & & \\ \cline{1-1}  & MS-2 & 36.33 & 0.67\% & & & & \\ \cline{1-1}  & MS-3 & 31.51 & 1.00\% & & & & \\ \cline{1-1}  & MS-4 & 38.64 & 0.87\% & & & & \\ \hline \hline \end{tabular}
\end{table}
Table 9: Main results of corroded specimens B30, experimental vs. numerical.  
Figure 13: Comparison between experimental and numerical response, corroded specimens, MS 1. (**a**) column B25, (**b**) column B30.  
Similar comments can be drawn for column B30: a good approximation of the ultimate load, but a poor prediction of the pre-yield behaviour are found. Furthermore, given the reduction of the mechanical properties due to uniform corrosion, an overestimation of the capacity was expected for the column with pitting phenomenon, as B30. As a matter of fact, this outcome is obtained in the negative load direction only. The main results for the numerical cyclic behaviour of modelling strategy 1 are reported in Tables 8 and 9.