# A Study on the Seismic Performance of Steel H-Column and T-Beam-Bolted Joints
## 4 Parametric Analysis
### Parameter Analysis of Axial Compression Ratio  
The stress cloud diagram of the node and column wall under different axial compression ratios is presented in Figure 22. The variation in the axial compression ratio has a negligible impact on the stress distribution of the joints. With an increase in the axial compression ratio, the yield area at the bolt hole and the tension area in the joint region increase slightly. Additionally, the stress at the top of the square steel-tube column rises as the axial compression ratio increases. Due to the partition within the column, the wall bulging of the square steel-tube column is not obvious. The hysteresis curves of nodes under different axial compression ratios are depicted in Figure 23. With the increase in the axial compression ratio, the contraction of the hysteresis curve increases slightly. This indicates that the change in the axial compression ratio has a minor impact on the sliding of high-strength bolts. The envelope area of the curve enlarges as the axial compression ratio rises, suggesting that the seismic performance of the node gradually improves. Figure 24 presents the skeleton curves of nodes under different axial compression ratios. The analysis results indicate that as the axial compression ratio increases, the yield load and bearing capacity of the space nodes gradually decline. Compared with the BASE node, the yield load of the BZY-5 node decreases by approximately 8%, and the bearing capacity decreases by about 9%. In contrast, compared with the BASE node, the yield load of the BZY-1 node increases by about 2.5%, and the bearing capacity increases by about 3%. The yield displacement of the joint decreases as the axial compression ratio increases. When the axial compression ratio increases from 0.2 to 0.6, the ductility coefficient of the joint rises, increasing from 2.41 to 2.69. The change in the axial compression ratio has a negligible impact on joint stiffness. The initial stiffness slightly decreases with the increase in the axial compression ratio, with a maximum reduction of approximately 3%. In summary, as the axial compression ratio increases, the yield load and bearing capacity  
Figure 22: Stress of 0.2 and 0.6 axial compression ratio, (**a**) BZY-1, (**b**) BZY-5. of the joint decrease significantly, the ductility coefficient increases slightly, and the initial stiffness decreases slightly. The energy-dissipation curve of the nodes is presented in Figure 25. As the horizontal displacement continuously increases, the energy consumption of the nodes gradually rises. The increase in the axial compression ratio has a negligible impact on the energy-dissipation capacity of the nodes, and there is little difference in the energy dissipation among various nodes. However, as the axial compression ratio increases, the equivalent viscous damping coefficient gradually increases. When the displacement is the same, the dissipated energy of each node shows little variation, but the bearing capacity decreases significantly with the increase in the axial compression ratio, causing the equivalent viscous damping coefficient to increase accordingly. Although the bearing capacity of the node decreases as the axial compression ratio increases, the difference in the weekly energy consumption is slightly smaller, and the energy-dissipation efficiency increases. In conclusion, the increase in the axial compression ratio enhances the energy consumption capacity of the node. With the increase in axial compression ratio, the initial slope of skeleton curve decreases slightly (the maximum decrease is about 3%), but the overall stiffness degradation is not significant. When the axial compression ratio increases from 0.2 (BZY-1) to 0.6 (BZY-5), the ductility coefficient increases from 2.41 (\(\Delta_{\mathrm{u}}/\Delta_{\mathrm{y}}=104/43.1\)) to 2.69 (\(\Delta_{\mathrm{u}}/\Delta_{\mathrm{y}}=104/38.7\)) by 11.6%. When the axial compression ratio is 0.2 (BZY-1), the equivalent damping coefficient is 0.22.