Numerical Investigation of I-Shaped Beam to Concrete Filled Tube Column Connection Without Continuity Plate

Circular columns are increasingly being used in today's construction industry. Proper construction beam-circular column connections are an important problem in steel moment resisting frames with this type of connection. TahamouliRoudsari et al. introduced a new I-shaped beam-circular concrete-filled column connection in 2020. This connection makes use of a strengthened U-shaped profile as an external stiffener with simple detailing. Experimental tests showed that the connection satisfies code-specified criteria for rigid connections. The main objective of the present work is to present design guidelines and a more accurate numerical investigation of the detailing introduced by TahamouliRoudsari et al. For this, in the first step, a numerical model of the experimental specimen was constructed and verified in the ABAQUS finite element software. Then, through multiple nonlinear finite element analyses, it has been demonstrated that this type of connection can meet all the requirements of special moment resisting frames with rigid connections. The minimum thickness for the strengthened U-shaped profile has been determined in such a way so that the plastic hinge could be created in the beam and the connection would have sufficient stiffness to be categorized as fully restrained. The effects of the geometry of the stiffened channel link and the column-to-beam section modulus ratio on the behavior of the connection were investigated and a relationship has been developed to calculate the thickness of the stiffened channel profile. Also, evaluating the effects of axial loading in the column showed that the thickness of the U-shaped profile and the stiffeners have no bearing on the axial load applied to the column.