Study on Mechanical Performance of Built‐In Octagonal Encase Steel Core Tube Fully Bolted Assembly CFSST Column Connection Joint

ABSTRACT This paper proposes a built‐in octagonal encase steel core tube fully bolted assembly CFSST column connection joint (OCFSST). The proposed static test study was carried out on this connection joint and the welded CFSST column connection joint (WCFSST), and the data were processed, analyzed, and compared in terms of hysteresis curves, skeleton curves, stiffness degradation, displacement ductility, bolt preload, strain changes, and the joint core area displacement angle. The average value of the horizontal bearing capacity of this joint is 5.60% higher than that of the welded CFSST column connection joint, which proves that this joint has better mechanical performance. The average difference of the hysteresis curves, skeleton curves, and stiffness degradation curves derived from finite element and test data is not more than 8.13%, which proves that the finite element simulation method is effective. In addition, octagonal encase steel core tube, self‐tapping bolts, and concrete have a good deformation co‐ordination property, which can ensure the safety and stability of the structure. The OCFSST meets the performance design goal of “strong joints, weak components” and can improve the site construction efficiency, which has a good prospect for application.