Seismic performance of self-tapping bolts-octagonal core sleeve flange square steel column connection

This study proposes a fully bolted connection joint for a square steel column incorporating an octagonal core sleeve. To ensure smooth assembly of the joint at the construction site, a certain gap is maintained between the core sleeve and the square steel column. However, this gap may exert a certain influence on the seismic performance of the joint. To enhance the seismic performance of the joints, the application of self-tapping bolt technology is recommended for optimizing the design of the joints. Based on these considerations, this study designed and conducted quasi-static tests on two specimens: the self-tapping bolt-octagonal core sleeve flange square steel column connection joint (SOFC) and the traditional column-column welded connection joint (TWC). The seismic performance of the two connection joints was compared and analyzed. The test results demonstrate that the SOFC specimen achieves the seismic design goal of “strong-joints and weak-members,” with a maximum bearing capacity of −1128.17 kN·m, which represents a 11.42 % improvement over that of the TWC specimen. Furthermore, the total energy dissipation of the two specimens across all loading levels differs by 11.2 %, indicating that their seismic performance is comparable. Additionally, a finite element numerical simulation was also performed to analyze the failure mode of the SOFC model in the limit state, clarify its failure path, and verify that the use of self-tapping bolts can effectively optimize the joint force transmission and improve the seismic performance.