# A Study on the Seismic Performance of Steel H-Column and T-Beam-Bolted Joints
## 4 Parametric Analysis
### Parameter Analysis of Column Wall Thickness  
The stress cloud diagram of the column wall at different thicknesses is depicted in Figure 19. As can be observed from the stress cloud diagram, with the increase in the column wall thickness, the yield area around the bolt holes of the square steel pipe column wall gradually diminishes, and the degree of column wall buckling also decreases. When the wall thickness is 10 mm and 12 mm, the column wall in the node domain experiences deformation and damage, with relatively high wall stress. In the design process, it is necessary to control the wall thickness of the square steel pipe to ensure that wall damage does not occur with an appropriate amount of steel usage. The stress cloud diagram of the column wall at different thicknesses is depicted in Figure 19. As can be observed from the stress cloud diagram; with the increase in the column wall thickness, the yield area around the bolt holes of the square steel pipe column wall gradually diminishes, and the degree of column wall buckling also decreases. When the column wall thickness is 10 mm (BZB-1), the main failure modes are column wall buckling and bolt-hole tearing. Due to the thin column wall, the stress concentration around the bolt hole is significant, resulting in local buckling of the column wall at the initial stage of loading (Figure 19a). With the increase in displacement, the buckling region expands, and finally the edge of the bolt hole tears due to excessive deformation, showing brittle failure characteristics (\(\Delta_{\text{u}}/\Delta_{\text{y}}\) = 2.1, low ductility coefficient). When the thickness of the column wall increases to 18 mm (BZB-5), the failure mode changes to the formation of the plastic hinge at the beam end. Due to the significant increase in column wall stiffness (38.12% increase in initial stiffness compared to BZB-1), stress concentration is transferred to the flange of the H-shaped steel beam, and the plastic hinge is eventually formed at the beam end (Figure 19b). In this model, the nodes exhibit ductile failure characteristics (\(\Delta_{\text{u}}/\Delta_{\text{y}}\) = 3.5, ductility coefficient is significantly improved). The results demonstrate that as the column wall thickness increases, the yield load and bearing capacity of the joints gradually rise. In comparison with the BZB-1 node, the yield load of the BZB-5 node has increased by 37.85%, and the bearing capacity has increased by 33.4%. Compared with the BASE node, the yield load of the BZB-5 node has increased by  
Figure 19: Stress of 10 and 18 column wall thickness, (**a**) BZB-1, (**b**) BZB-5. 7.58%, and the bearing capacity has increased by 6.71%. Conversely, with the decrease in column wall thickness, the yield load and bearing capacity of the joint are reduced. Compared with the BASE node, the yield load of the BZB-1 node has decreased by 21.96%, and the bearing capacity has decreased by 20.01%. As the column wall thickness increases, the joint yield displacement gradually decreases, while the ductility coefficient increases. The node stiffness also increases with the increase in column wall thickness. Compared with the BZB-1 node, the stiffness of the BZB-5 node has increased by 38.12%. Additionally, compared with the BASE node, the stiffness of the BZB-5 node has increased by approximately 13%. When the column wall thickness increases from 10 mm to 18 mm, the initial stiffness increases from 8.7 kN/mm to 12.0 kN/mm, an increase of 37.9%. When the column wall thickness increases from 10 mm (BZB-1) to 18 mm (BZB-5), the ductility coefficient increases from 2.1 to 3.5 (\(\Delta_{\text{u}}/\Delta_{\text{y}}=104/29.7\)) by 66.7%. Skeleton curves of nodes with different column wall thicknesses are shown in Figure 20, and the energy-dissipation curve of the nodes is shown in Figure 21. As the wall thickness of the square steel-pipe column increases, the joint energy consumption gradually rises while the equivalent viscous damping coefficient first decreases and then increases.