## 4 Finite Element Analysis
### Stress Cloud, Hysteresis Curve, and Skeleton Curve  
Figure 24 shows the stress clouds for connectors with different thicknesses. The damage phenomenon of the ALC panel is similar for all four groups of specimens, which all appear around the beam-column joints. This is very different from the hook head bolt group, which appears around weld between bolt and angle steel. In terms of the ALC panel, the maximum stress value of 6 mm is 2.527 MPa, which is more than 5% lower than the other groups. When the displacement reaches the limit value of the elastic-plastic displacement angle 1/50 (\(\Delta\) = 60 mm), the stress value of TK-6 is 1.986 MPa. Its stress is the smallest among the five groups (as shown in Table 6). It indicates that the thinner connector has more elastic deformation under seismic loading. It reduces the damage around the bolt hole and optimizes the force performance of the ALC panel.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Component Number** & **Type** & **Features** \\ \hline GT & Traditional connectors & 6 mm \\ TK-6 & Fabricated new connectors & 6 mm \\ TK-8 & Fabricated new connectors & 8 mm \\ TK-10 & Fabricated new connectors & 10 mm \\ TK-12 & Fabricated new connectors & 12 mm \\ \hline \hline \end{tabular}
\end{table}
Table 5: Simulation connector type.  
Figure 24: Stress clouds images: **(a)** TK-6; **(b)** TK-8; **(c)** TK-10; **(d)**TK-12; and **(e)** GT.  
The hysteresis curves images for GT, TK-6, TK-8, TK-10, and TK-12 are presented in Figure 25. Although their trends are basically the same, they have some differences in peak displacement and peak load. Specifically, the hysteresis curve is fuller as the thickness of the connector increases. At small displacements, the five sets of images appear to largely coincide with the thin hysteresis loops where the specimens are in the linear elastic phase. With the displacement increases, the tendency of specimen TK-6 decreases earlier than TK-8, TK-10, and TK-12, but this situation is much better than the GT group.  
Figure 26 shows the relationship of the load-displacement skeleton curves for GT, TK-6, TK-8, TK-10, and TK-12. The five curves have the same variation. The peak of the image becomes more prominent as the thickness of the connector increases. TK-6 has a slight difference in its peak compared to the other groups, and its descent is relatively flat. It indicates that the different thickness connectors improve the bearing capacity and stiffness of the ALC panel steel frame, although the effect is slight.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Specimen**} & \multicolumn{2}{c}{**Characteristic Point**} & \multicolumn{2}{c}{**Maximum Point**} \\ \cline{2-5}  & **Displacement** & **Mises Stress** & **Displacement** & **Mises Stress** \\  & **(mm)** & **(MPa)** & **(mm)** & **(MPa)** \\ \hline TK-6 & 60 & 1.986 & 105.00 & 2.527 \\ TK-8 & 60 & 2.076 & 105.00 & 2.785 \\ TK-10 & 60 & 2.042 & 105.00 & 2.612 \\ TK-12 & 60 & 2.174 & 105.00 & 2.659 \\ GT & 60 & 4.018 & \(-\)105.00 & 5.133 \\ \hline \hline \end{tabular}
\end{table}
Table 6: ALC panel bolt hole stress.  
Figure 25: Hysteresis curve of FEM: (**a**) TK-6 and TK-10; (**b**) TK-8 and TK-10; (**c**) TK-10 and TK-12; (**d**) TK-10 and GT.