Experimental and theoretical investigation of self-tapping bolt core tube flange column connection of prefabricated steel structure

Abstract

This study proposes a column-column connection with self-tapping bolts, a core tube, flange plates, and high-strength bolts for a prefabricated steel structure, which can avoid on-site welding of traditional steel structure closed section columns and realize efficient assembly of vertical steel structure components. To determine the mechanical characteristics of the self-tapping bolt core tube flange column connection (SCFC) and the effect of the core tube and self-tapping bolts on SCFC, quasi-static tests were performed. According to the test results, altering the core tube thickness within a specific range had no discernible impact on the SCFC's seismic performance metrics, including hysteresis performance, skeleton curve, and stiffness degradation. The failure modes of test specimens were all steel fractures at the column foot, proving that SCFC can realize the seismic design goal of “strong joint, weak member.” The force mechanism of the SCFC and slip mechanism of the self-tapping bolt were explored. A finite element model (FEM) was established, and the results agreed well with the test results, confirming the accuracy of the FEM. Finite element parametric analyses were performed to further clarify the impact of the thickness of the core tube on the connection performance. Combined with the test and FEM results analyses, the bearing capacity calculation formulas of the SCFC were proposed based on the yield-line theory and verified by the results of the test and FEM. The design criteria for the SCFC were further proposed.