# A Study on the Seismic Performance of Steel H-Column and T-Beam-Bolted Joints
## 5 Conclusions
This paper recommends that the wall thickness of the joint column should be no less than the flange thickness of the steel beam and should not be less than 12 mm. When the column wall thickness increases from 10 mm to 12 mm, the yield load and bearing capacity increase by 37.85% and 33.4%, respectively, compared with the 10 mm thick column wall node (see Figure 20). When the column wall thickness increases (e.g., from 10 mm to 18 mm), the column wall stiffness increases significantly (initial stiffness increases by 38.12%), effectively limiting local buckling around the bolt hole (Figure 19b). The thicker column wall delays brittle failure (e.g., tearing) by preventing stress concentration, which in turn guides the plastic deformation to the H-shaped steel-beam flange, resulting in a plastic hinge at the beam end (\(\Delta\text{u}/\Delta\text{y}\) increased from 2.1 to 3.5). 5. As the axial compression ratio increases, the bearing capacity and stiffness of the joint decrease, yet the degree of stiffness reduction is not conspicuous. Conversely, the energy-dissipation capacity and ductility increase with the rise in the axial compression ratio. 6. The increase or decrease in the pre-tightening force of the high-strength bolt has no impact on the overall performance of the node. The yield load, bearing capacity, initial stiffness, and ductility of the joints with high-strength bolts do not change significantly as the preloading force varies. When the bolt preload increases from 180 kN to 270 kN, the yield load fluctuates \(\pm\)1.9% (372.1 kN-379.5 kN), and the peak load fluctuates \(\pm\)1.3% (436.8 kN-442.3 kN) (Table 3, Figure 28). These fluctuations are much lower than the material strength dispersion (Q355B steel yield strength standard deviation of about 5%). 7. Based on the research results, the recommended design threshold is given: The web thickness of the T-shaped part 1 is \(\geq\)18 mm (to ensure the formation of the plastic hinge, \(\Delta\text{u}/\Delta\text{y}\geq 3.0\)); column wall thickness \(\geq\) 12 mm (to prevent column wall buckling, initial stiffness \(\geq\) 10 kN/mm); and axial compression ratio \(\leq\) 0.4 (equilibrium bearing capacity and energy consumption, equivalent damping \(\geq\) 0.25). In the future, it is planned to expand the test validation, carry out low-cycle repeated tests on full-size joints, verify the prediction ability of the finite-element model for complex stress states (such as three-way stress), and supplement the parameter analysis of different steel strengths (such as Q420B). A long-term performance study was carried out to explore the durability and fatigue properties of the nodes under a corrosive environment. Combined with an electrochemical accelerated corrosion test, a life prediction model was established. A new type of connection was developed, combining the T-part connection with the semi-rigid node, further improving energy consumption efficiency and construction convenience by optimizing the bolt layout and contact surface treatment. Engineering application verification was conducted, application of this node in actual steel frame projects was piloted, its real response in earthquakes through health monitoring systems was evaluated, and data support for code revision was provided. Conceptualization, J.Y. ; Methodology, J.Y. ; Software, K.Z. ; Validation, X.H. ; Formal analysis, H.J. and Y.G. ; Investigation, X.H. and Y.G. ; Data curation, H.J. ; Writing--original draft, K.H. ; Writing--review & editing, [PERSON]; Visualization, [PERSON]; Supervision, [PERSON]; Project administration, [PERSON] All authors have read and agreed to the published version of the manuscript. This research received no external funding. Not applicable. Data Availability Statement: Data are contained within the article. Authors [PERSON], [PERSON], [PERSON], and [PERSON] were employed by the company Power China Hubei Electric Engineering Co., Ltd. Author [PERSON] was employed by State Grid Hubei Zhongchao Construction Management Company.