# Mechanical Performance of Confined Autoclaved Fly-Ash-Brick Masonry Walls under Cyclic Loading
## 3 Numerical Simulation Analysis and Verification
### Holes and Seismic Performance of Assembly Autoclaved Fly-Aslt-Brick Walls  
#### 4.3.1 Influence of Window Hole Dimensions on Seismic Performance of the Walls  
Compared to wall ZWZ-1 without an opening, walls ZWZ-4, ZWZ-5 and ZWZ-6, with different window hole dimensions, were analyzed comparatively to study the influence of different hole dimensions on the bearing capacity, stiffness degradation and displacement ductility of the walls.  
The window holes of walls ZWZ-4, ZWZ-5 and ZWZ-6 were located at the center of the wall, as shown in Figure 22. Meanwhile, the dimension and parameters of walls ZWZ-4,  
Figure 21: Plastic strain magnitude of the walls with different mortar strength: (a) wall ZWZ-2-2; (b) wall ZWZ-1; (c) wall ZWZ-3.  
Figure 20: Load–displacement and stiffness–displacement curves of the walls with different mortar strength: (a) load–displacement curves; (b) stiffness–displacement curves.  
ZWZ-5 and ZWZ-6 are shown in Table 6. From Equation (9) and simulation results, the bearing capacity values of the walls with different window holes' dimensions are shown in Table 8. The load-displacement and stiffness-displacement curves of the walls are shown in Figure 23. The stress nephogram of the walls with different window holes' dimensions are shown in Figure 24.  
According to Table 8, compared to wall ZWZ-1 without an opening, the cracking loads of walls ZWZ-4, ZWZ-5 and ZWZ-6 were decreased by 54%, 63% and 80%, respectively; the ultimate loads were decreased by 40%, 55% and 74%, respectively; the failure loads were decreased by 28%, 34% and 61%, respectively; and the displacement ductility ratios were decreased by 41%, 52% and 48%, respectively.  
Figure 23: Load–displacement and stiffness–displacement curves of the walls with different window holes’ dimensions: (**a**) load–displacement curves; (**b**) stiffness–displacement curves.  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Number**} & **Distribution** & **Cracking** & **Cracking** & **Ultimate Load** & **Ultimate** & **Failure Load** & **Failure** & **displacement** & **\#M/\(\Delta\)u** \\  & **Holes** & **Load P\({}_{\text{\tiny{e}}}\) (\&\) **(\&)** & **Arc (mm)** & **P\({}_{\text{\tiny{e}}}\) (\&)** & **\(\Delta\)u (mm)** & **P\({}_{\text{\tiny{f}}}\) (\&)** & **\(\Delta\)f (mm)** & **\#M/\(\Delta\)u** \\ \hline ZWZ-1 & Without opening & 199 & 0.62 & 303 & 3.16 & 188 & 13.75 & 4.35 \\ ZWZ-4 & 750 \(\times\) 900 & 91 & 0.52 & 183 & 3.54 & 135 & 9.11 & 2.57 \\ ZWZ-5 & 1000 \(\times\) 1200 & 73 & 0.78 & 135 & 3.89 & 124 & 8.14 & 2.09 \\ ZWZ-6 & 1200 \(\times\) 1200 & 39 & 0.51 & 78 & 1.87 & 73 & 4.23 & 2.26 \\ \hline \hline \end{tabular}
\end{table}
Table 8: Bearing capacity values of the walls with different window holes’ dimensions.  
Figure 22: Wall models with different window holes’ dimensions: (**a**) wall ZWZ-4; (**b**) wall ZWZ-5; (**c**) wall ZWZ-6.  
As can be observed from Figures 23 and 24, with the increase in the window hole dimensions, the bearing capacity of the walls with holes was significantly decreased. The stress concentration near the hole was distinct. The color of the grid cell in the graph was deepened, indicating that the stress of the unit increased. With the large opening dimension, walls ZWZ-5 and ZWZ-6 reached the failure stage quickly after reaching the ultimate load, which led to the decline of the wall's bearing capacity. The stiffness of the wall with an opening was lower than that of the unopened wall, which indicated that the holes' dimensions have a great influence on the stiffness of the wall. With the increase in the hole dimensions, the stiffness of the walls decreased, and the slope of stiffness-displacement curves increased which indicated that the stiffness degradation rate of the walls increased.