## 5 Conclusions  
This paper compares the external hooked bolt connector and the pendulums Z-panel connector. The following conclusions can be drawn from the tested and numerical simulations.  
1. The damaged parts of the two groups of the external ALC panel tests are substantially different. For the FW-1 group, the damage first appears at the joints of the panels with clear penetration cracks when the displacement angle reaches 1/500 (\(\Delta\) = 6 mm). For the FW-2 group, the damage first appears at the bottom span of the panel with slight cracks when the displacement angle reaches 1/200 (\(\Delta\) = 15 mm). It was proved that the pendulums Z-panel connector optimizes force performance of the ALC panel steel frame, enhances energy dissipation capacity, ensures the integrity of the ALC panel, and avoids the risk of secondary instability.
2. The pendulums Z-panel (FW-2) connector method is similar to the semi-rigid connector in terms of the skeleton curve and the stiffness degradation curve in terms of experimental phenomenon and data. The overall damage phenomenon of the pendulums Z-panel connector group is significantly delayed compared to the external hooked bolt connector group because of the bolt sliding in the top long circular hole. This setting effectively releases the lateral force at the initial loading stage, then it reduces the damage to the ALC panel by the earthquake load under unfavorable working conditions and enhances the main structure's stability.
3. The connector is one of the significant influencing factors to ensure the stability of the external panel-frames synergistic system. Specifically, compared with FW-1, the yield load and peak load of FW-2 increase by 10.6% and 15.3%, respectively, and the yield displacement and peak displacement are increased by 12.6% and 29.9%, respectively. After reaching the peak load, the load capacity of FW-1 decreases rapidly, while the load capacity of FW-2 decreases slowly, although the initial stiffness of FW-2 is smaller. The analysis proves that this connector has good load carrying capacity and ductility.
4. The ABAQUS simulation revealed that the pendulums Z-panel connector of 6 mm has a larger load capacity and energy dissipation capacity than the external hooked bolt connector, which shows a better performance index. The TK-6 has a 7.6% decrease in load capacity compared to TK-10, and the decreasing segment is advanced. However, it has a similar change trend, and the stress around the ALC bolt hole is the smallest among the five groups. Having similar results for different thicknesses in the use of pendulums Z-panel connectors indicated that it would be more reasonable to use the 6 mm connector, which is the most economical solution for engineering.  
Conceptualization, K.D. and Y.L.; methodology, K.D.; software, K.D. and D.Z.; validation, Y.L.; formal analysis, D.Z.; investigation, K.D. and D.Z.; resources, K.D.; data curation, D.Z. and S.H.; writing--original draft preparation, K.D. and D.Z.; writing--review and editing, K.D. and Y.L.; visualization, D.Z.; supervision, K.D., Y.L. and W.S.; project administration,  
Figure 26: Skeleton curve of TK-6, TK-8, TK-10, TK-12, and GT.  
K.D. and W.S.; funding acquisition, K.D., Y.L. and W.S. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the University Synergy Innovation Program of Anhui Province (GXXT-2019-005).  
Not applicable.  
This research was financially supported by the University Synergy Innovation Program of Anhui Province (GXXT-2019-005), the University-Industry Collaborative Education Program of the Ministry of Education (202002129042), and the Scientific Research Project of Anhui Education Department- Key Project (KJ2020A0490).  
The authors declare no conflict of interest.