## 4 Analysis of the Seismic Performance of the Cantilever Truss Nodes Under Rare Earthquake Action
### Condition Selection  
Firstly, it is necessary to calculate the stress intensity of each bar section to obtain the most unfavorable working condition of the node. By obtaining the component information in the overall model of the ANSYS software, the internal force of each member under a single working condition can be directly calculated [33]. The internal forces of each component are combined with different working conditions, such as the combination of coefficients. The most unfavorable working conditions with the largest Von Mises stress are selected. Then, the internal forces under the most unfavorable working conditions are used for force analysis of the nodes [16]. According to the types of typical nodes, Node 2, Node 3, and Node 6 are taken as examples to analyze the internal forces of the lower chord bar, oblique belly bar, and horizontal bar under various design conditions. It can be seen that the combined internal forces controlled by the vertical rare earthquake are the largest because the nodes are located at the lower chord bar of the suspension truss, and the vertical forces play a controlling role in the process. The internal forces under the most unfavorable working conditions are listed in the following table. As shown in Table 2 to Table 2, the analysis working conditions of Node 3 are selected as an example, as shown in Table 8.  
Here, the working condition 43 is performed, and the corresponding load combination can be termed as \(1.0\)D + \(0.5\)L + \(0.4\)E\({}_{\text{X}}\) + E\({}_{\text{Z}}\). Meanwhile, D, L, E\({}_{\text{X}}\), and E\({}_{\text{Z}}\) respectively stand for the constant load, the live load, the X-direction earthquake--considering the bi-directional seismic torsional effect--and the response spectrum vertical earthquake. It can be observed from Table 8 and Figure 12a that the overall and the three nodes have different trends at different stages. Among them, Node 2 and Node 6 are relatively stable with small fluctuations, while Node 3 has relatively obvious undulating changes. The bending moment of XXG1 reaches 1800, and the bending moment of GKL1 reaches 2100. It can be observed from Figure 12b that the bars can fluctuate within a certain range. For example, XGI shows an upward trend at certain stages, and then it may tend toward being stable and can slightly decline. The data originating from FGIA may have different variation characteristics, such as fluctuating more frequently, and the data can be relatively stable within a specific interval. It can be also observed from Figure 12b that the fluctuations are relatively obvious. For example, the term XXGI has a large-scale increase and decrease tendency in certain intervals. The data originating from FGIA also show different change trends, including rising, falling, and stable stages.  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Build**} & \multicolumn{3}{c}{**Bending Moment (KN-m)**} & \multicolumn{3}{c}{**Shearing Force (KN)**} & \multicolumn{3}{c}{**Axial Force (KN)**} \\ \cline{2-9}  & **Node 1** & **Node 2** & **Node 3** & **Node 1** & **Node 2** & **Node 3** & **Node 1** & **Node 2** & **Node 3** \\ \hline XXG1 & 1800 & – & – & 4500 & – & – & –76,000 & –70,000 & – \\ FG1A & 2100 & – & – & – & – & – & 6100 & –14,000 & 238,143 \\ FG1B & – & – & – & – & – & – & 9700 & –12,800 & – \\ FG1C & – & – & – & – & – & – & – & –19,000 & – \\ FG1D & – & – & – & – & – & – & – & 11,000 & – \\ XXG1 & – & –70,000 & – & – & – & – & – & –70,000 & – \\ FG2 & – & – & – & – & – & – & –26,000 & –7000 & – \\ GKZ1 & – & – & – & – & – & – & – & –91,000 & – \\ FG3 & – & – & – & – & – & – & –11,000 & –900 \\ GKL1 & – & –7400 & – & – & – & – & –4600 & – \\ SXG2 & – & – & 540 & – & – & 2300 & – & – & 22,000 \\ \hline \hline \end{tabular}
\end{table}
Table 8: Internal force table for the most unfavorable working condition.