## 5 Conclusions  
The complicated node analysis methods are fully considered in this research. The SHELL63 element is used to simulate the complicated nodes, and the most unfavorable working conditions are selected for analysis. Then, the overall performance of the complicated nodes is fully considered. This research can effectively analyze the stress states of the nodes under the action of rare earthquakes. The conclusions drawn are as follows:  
(1) This research centers on the crucial area of complicated nodes within the ultra-limited steel structure in order to thoroughly analyze the distinctive properties within the structure. The mechanical features and the relevant key points in the design, as well as the construction, are also studied. These findings can provide both theoretical and practical guidance for resolving these complicated structural issues. According to the mechanical performance of different nodes, reasonable section forms are designed and appropriate materials are selected to optimize the structure of complicated nodes. Then these efforts can improve the overall safety performance of the structure and also control the construction costs to achieve economic feasibility. (2) Typical complicated nodes in the steel structure are selected for finite element analysis. The Von Mises stress of each node can exceed the yield strength and can enter the plastic deformation stage only in the stress concentration area. Moreover, the Von Mises stress in other areas of the node is less than the yield strength of steel, which can maintain the elastic state. The results that the overall performance of the node was good, and the designed components involved in the structure can meet the seismic design requirements under the action of rare earthquakes. The single K-node structure with a clear force transmission path is formed by the oblique belly rod. Then, the node form is optimized to ensure coordination between the components and effective force transmission. These efforts can effectively absorb and disperse the seismic energy when an earthquake occurs. Moreover, these experiences can reduce the degree of damage to the structure and improve the seismic performance of the overall structure. (3) In this study, the key construction technology of the steel nodes is investigated. Simpler, more efficient, and reliable combinations are proposed to meet the application requirements of various nodes in complicated structures. When the integrity of the nodes can be ensured, the design flexibility of steel nodes can be enhanced. These efforts can provide a theoretical basis for the seismic design of the ultra-limited steel nodes. (4) In this paper, the stress intensity of each member section is calculated to obtain the most unfavorable working conditions of the nodes, as shown in Figure 12 and Table 8. In the non-yielding stage, the Von Mises membrane stress and the combined membrane and bending stresses in the most unfavorable working conditions of node components are extracted when a rare earthquake is forced. N Nodes 1 to 6 meet the performance design requirements for the non-yielding state when a rare earthquake is forced. The  
Figure 18: The overall stress cloud chart of Node 6. (**a**) Film stress intensity under the most unfavorable conditions. (**b**) The bending stress strength of the film under the most unfavorable conditions. results illustrate that the overall performance of the nodes is good. The upper chord SXG1, the oblique belly rod FG1, and the vertical rod form the asymmetrical modality of Node 5. These efforts illustrate that Node 5 has better overall stability compared to the non-asymmetrical node. (5) The force and deformation analysis of complicated nodes is studied. Through finite-element simulation and actual structure monitoring, it is found that during the occurrence of rare earthquakes, the stress concentration in complicated node areas is extremely significant.