# Retrofitting Masonry Walls against Out-Of-Plane Loading with Timber Based Panels
## 4 Numerical Study
### Numerical Simulation of Large-Scale Test on a Masonry Wall Specim
#### 4.3.2 Summary of Results Obtained from Large-Scale Masonry Wall Numerical Analysis  
The results obtained from the numerical simulation of the large-scale walls were compared with the test results in terms of both the capacity and failure mode. The comparison shows a relatively good agreement between the numerical and experimental results. Figure 19 shows the failure of the model alongside the actual damaged specimens obtained from the test. For the plain wall (PW1115), the comparison (see Figure 19a) indicates that the specimen failure occurred in similar bed joints, which is in the ninth and tenth row of \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Parameter**} & \multicolumn{3}{c}{**MP00**} & \multicolumn{3}{c}{**MPOSB**} \\ \cline{2-7}  & **Test** & **FE Model** & **\% Difference** & **Test** & **FE Model** & **\% Difference** \\ \hline Peak load (N) & 2860 & 2800 & 2.1 & 21,100 & 22,100 & 4.5 \\ Displacement (mm) & 0.058 & 0.055 & 5.0 & 18.7 & 19.4 & 3.6 \\ Toughness (Nmm) & 1050 & 1040 & 1.0 & 257,000 & 271,000 & 5.0 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Comparison of model and test average results (MP). Figure 18: Masonry wall model (2 SRW1115-NM as an example): (**a**) boundary conditions, (**b**) loading, (**c**) side view with indication of applied loads and boundaries. the experimental specimen. Correspondingly, the tension damage in the model is largest in the tenth row. The failure in the test specimen crossed the perpendicular joint due to the weaker zone in the perpend joint. This weakness was not observed in the numerical model because the property of the mortar joint is the same for the bed joint and perpend joint. Indeed, the bed joint is the one in maximum tension during loading. The experimental failure was only due to variance in the specimen joint during construction, which makes the perpend joint in that zone weaker than the bed joint. Moreover, the numerical failure of the one side retrofitted model (ISRW1115) was compared alongside the damaged specimen from the test (Figure 19b). The damage pattern  
Figure 19: Failure pattern of large-scale wall (experimental and FE model): (**a**) plain wall (PW1115), (**b**) one side retrofitted wall (ISRW1115), (**c**) Double side retrofitted wall (2 SRW1115). shows that the OSB panel at the back of the specimen failed after the mortar joint failed. The location at which the OSB failed in the model is similar to what was observed in the test with the failure point being within two rows of connections. Similar to the previous two models, the observed failure pattern for both the numerical and experimental specimens was compared for the two-sided retrofitted specimens, as shown in Figure 19c. The failure pattern of the model developed for 2 SRW1115 is also in good agreement with the experimental failure. The damage pattern indicates that the OSB panel in the tension side (at the back of the specimen) failed after the mortar joint failed. The location at which the OSB failed in the model is similar to what was observed in the test with the tensile stresses spreading across the middle of the panel. The OSB in the compression face did not fail, as also seen in the experiment. The damage shown on the OSB on the compression side (i.e., loading face) only occurred after the failure and, as such, not replicated in the model. Additionally, the load-displacement curve obtained from both the numerical analysis and experimental test is presented in Figure 20. The toughness, maximum load and corresponding displacement at the failure of the model are within less than 10% of the average results obtained from the test (Table 7). Figure 20a shows that there is a little variance in the displacement for applied load higher than 24,000 N; this variation is due to the movement of the wall during testing at the initiation of the crack. This behaviour was noticed during the experiment ([6]); and it is primarily due to instability of the specimen caused by the test arrangement (as also indicated in [34; 35]).