# Modeling of RC Moment Frame Retrofit with Mortar Walls Reinforced with Steel Wire Mesh
## 4 Discussion  
Current construction codes require detailed analyses for structural retrofitting considering the performance during seismic events. Therefore, the computational models used to evaluate existing infrastructure require nonlinear structural analysis and damage estimates. For structural retrofitting, nonlinear computational modeling is a widely used tool, but it must represent the connectivity between existing and new elements. This study proposes recommendations on the structural modeling of fiber elements to represent reinforced concrete (RC) moment frames retrofitted with mortar walls reinforced with steel wire mesh. A key finding of this study was that modeling these retrofitted moment frames with insufficient connectivity nodes and constraint conditions leads to the inaccurate estimation of capacity curves. SeismoStruct computational models do not have the option to define shear wall transverse sections with different materials for border and web sections, so the retrofitted shear wall was defined with individual border and web elements, which are connected by default program options. This study found that insufficient connectivity and \begin{table}
\begin{tabular}{c c c c c c c c} \hline  & & \multicolumn{2}{c}{**Maximum**} & \multirow{2}{*}{**Error**} & \multirow{2}{*}{**Stiffness**} & \multirow{2}{*}{**Error**} & \multicolumn{2}{c}{**Residual**} & \multirow{2}{*}{**Error**} \\  & & & & & & & **Strength** \\ \cline{3-8}  & & **(kN)** & & & & & **(kN)** & **(\%)** \\ \hline \multirow{6}{*}{**C**} & Benchmark capacity curve & 558.93 & - & 166,185.41 & - & 450.88 & - \\  & Model without discretization & 439.73 & 21.33 & 67,138.20 & 59.60 & 227.91 & 49.45 \\  & Model with discretization 1 & 507.27 & 9.24 & 90,077.46 & 45.80 & 409.85 & 9.10 \\  & Model with discretization 2 & 543.22 & 2.81 & 97,038.72 & 41.61 & 422.50 & 6.29 \\  & Model with discretization 3 & 560.69 & 0.32 & 112,138.88 & 32.52 & 432.04 & 4.18 \\ \hline \multirow{6}{*}{**C**} & Benchmark capacity curve & 279.46 & - & 21,649.63 & - & 225.44 & - \\  & Model without discretization & 212.37 & 24.01 & 11,829.18 & 45.36 & 111.83 & 50.40 \\  & Model with discretization 1 & 261.79 & 6.33 & 15,737.77 & 27.31 & 207.48 & 7.97 \\  & Model with discretization 2 & 271.65 & 2.80 & 16,025.25 & 25.98 & 213.24 & 5.41 \\  & Model with discretization 3 & 271.12 & 2.99 & 15,707.89 & 27.45 & 211.96 & 5.98 \\ \hline \multirow{6}{*}{**C**} & Benchmark capacity curve & 186.31 & - & 6504.93 & - & 150.29 & - \\  & Model without discretization & 145.64 & 21.83 & 4378.05 & 32.70 & 67.49 & 55.09 \\ \cline{1-1}  & Model with discretization 1 & 173.54 & 6.85 & 5973.42 & 8.17 & 139.72 & 7.04 \\ \cline{1-1}  & Model with discretization 2 & 187.44 & 0.61 & 6082.98 & 6.49 & 144.08 & 4.13 \\ \cline{1-1}  & Model with discretization 3 & 188.11 & 0.97 & 5821.39 & 10.51 & 143.44 & 4.56 \\ \hline \end{tabular}
\end{table} 
Table 7: Summary of differences in relative percentage between the benchmark and computational capacity curves. constraint conditions produce issues in the capacity curve prediction, like underestimating maximum strength, initial stiffness, and residual strength. Improving the modeling of these systems was required to better evaluate the performance of the existing moment frames retrofitted with mortar walls reinforced with steel wire mesh. Since the capacity curves are a primary tool for performance-based design and assessment, accurate predictions using computational models are critical for implementation. In general, there are standard procedures and models that work well for typical systems (moment frames and shear walls), but new systems (like the one presented in this study) cannot use the same procedure for standard systems. Therefore, the computational models for nonstandard systems must be calibrated to achieve accurate and reliable results. This study identifies an easy solution to reduce issues in capacity curve predictions for fiber computational models of moment frame systems retrofitted with mortar walls reinforced with steel wire mesh.