# Seismic Behaviour of CFST Space Intersecting Nodes in an Oblique Mesh
## 6 Discussion
### Space Intersecting Angle
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline
**Control** & \multirow{2}{*}{**Component Name**} & \multirow{2}{*}{**\(F_{y}\) (+)**} & \multirow{2}{*}{\(F_{y}\) (\(-\))} & \multirow{2}{*}{\(F_{u}\) (+)} & \multirow{2}{*}{\(F_{u}\) (\(-\))} & \multirow{2}{*}{\(\delta_{u}\)} & \multirow{2}{*}{\(\Theta\)} & \multirow{2}{*}{\(k_{c}\)} \\
**Parameters** & & & & & & & & \\ \hline \multirow{4}{*}{Plane angle} & Node-Plane20 & 5628.60 & 4130.05 & 6199.52 & 5246.72 & 1.95 & 456.59 & 0.827 \\  & Node-Plane50 & 6275.72 & 4156.00 & 6697.62 & 4977.11 & 1.81 & 336.06 & 0.893 \\  & Node-Plane70 & 6513.06 & 4372.05 & 71186.35 & 5451.78 & 1.56 & 535.89 & 0.959 \\  & Node-Plane90 & 6234.46 & 4316.43 & 7111.80 & 5289.62 & 1.09 & 542.79 & 0.949 \\ \hline \multirow{4}{*}{Out-of-plane} & Node-Con0.00 & 4529.30 & 3847.95 & 4709.06 & 4651.71 & 102.90 & 464.23 & 0.628 \\  & Node-Con0.05 & 5350.91 & 3775.79 & 5401.88 & 4606.21 & 50.07 & 330.19 & 0.721 \\  & Node-Con0.10 & 5888.68 & 3873.45 & 6333.64 & 4681.38 & 46.88 & 352.01 & 0.845 \\  & Node-Con0.20 & 6024.17 & 4275.48 & 6314.38 & 5179.72 & 1.32 & 395.24 & 0.842 \\ \hline \multirow{4}{*}{Steel content} & Node-Steel0.05 & 4578.04 & 1499.75 & 4910.12 & 1843.28 & 1.20 & 367.54 & 0.823 \\  & Node-Steel0.20 & 7552.80 & 6272.14 & 9026.46 & 7853.92 & 45.20 & 591.60 & 0.976 \\  & Node-Steel0.25 & 8463.85 & 7520.42 & 10,377.04 & 9079.87 & 39.90 & 725.48 & 0.893 \\ \hline \multirow{4}{*}{Concrete strength} & Node-Concrete30 & 4641.21 & 4113.87 & 5336.96 & 5100.29 & 1.44 & 748.13 & 1.092 \\  & Node-Concrete50 & 5520.37 & 4108.39 & 5576.77 & 5147.45 & 1.55 & 728.89 & 0.971 \\ \cline{1-1}  & Node-Concrete70 & 5492.21 & 4140.10 & 5929.77 & 5156.74 & 1.63 & 752.17 & 0.947 \\ \cline{1-1}  & Node-Concrete120 & 6463.56 & 4166.67 & 7004.76 & 5193.63 & 2.15 & 806.57 & 0.792 \\ \hline \end{tabular} Note: \(F_{y}\) denotes the yield load of the node, and the yield point is defined according to references [32; 33]. The method for determining the yield point is as follows: the straight line passing through the origin and 0.75 \(F_{u}\) point intersects with the horizontal line passing through the peak point of the curve at a certain point, which is the yield point, where (+) and (\(-\)) denote compression and tension along the axis, respectively. \(F_{u}\) denotes the ultimate load of the node, and the interpretation in parentheses is the same as that of \(F_{y}\). \(\delta_{u}\) denotes the maximum displacement of the node in the plane, 0 denotes the total energy dissipation of the node, and \(k_{c}\) denotes the strength enhancement coefficient [34]. \(k_{c}=F_{u}/F_{u0}\), where \(F_{u0}=\Delta f_{y}+\Delta f_{c}\) represents the simple superposition of the bearing capacity of the steel tube and concrete. It intuitively reflects the mutual compensation effect between the steel tube and the concrete.  
\end{table} 
Table 3: _Cont._capacity of the component with a space angle of 3\({}^{\circ}\) increased linearly, indicating that the component can still maintain a large energy dissipation capacity in the later large displacement cycles. However, the energy dissipation capacity of the component with a space angle of 5\({}^{\circ}\) increased more slowly after the fifth cycle, and the energy dissipation in the last cycle was only 28.39% of the total energy dissipation. The total energy dissipation was only 76% of the total energy dissipation of the component with a space angle of 3\({}^{\circ}\). Components with a spatial angle of 4\({}^{\circ}\) still maintain a significant energy dissipation capacity throughout the entire loading stage, mainly due to their excellent load-bearing capacity and sizeable vertical displacement of nodes. However, it was prone to lateral instability and failure due to the difficulty in controlling the out-of-plane displacement, and it was not recommended to use components with space angles greater than or equal to 4\({}^{\circ}\) in engineering practice. Figure 6 shows the Mises stress and concrete compression damage of components at different space angles.