Experimental and theoretical investigation of prefabricated separated core tube flange column connection joint

This paper suggests a separated core tube flange connection column joint to ensure the horizontal shear performance of box section steel columns at the flange connection to meet the performance requirements of column-to-column connection in high-rise buildings and the effective connection of steel columns at the joints. Low cycle reciprocating loading tests were conducted on three specimens with different parameters (separated core tube and stiffeners) to study the seismic mechanical performance of the connection and the finite element analysis (FEA) of separated core tube column connection joint was performed. The result of the experimental study shows that the separated core tube connection joints have fuller hysteresis curves and higher energy dissipation performance, as well as less high-strength bolt tension at the same interlayer displacement angle. This investigation provides experimental evidence of the deformation compatibility of the separated core tube connection. The mechanical properties of the separated core tube connection is basically the same as that of the welded connection, which can realize the rigid connection of the steel box section column. According to the numerical simulation, the failure mode and mechanism of the connection were obtained. Based on the results of tests and the finite element numerical model, further analysis to the rotational performance of the separated core tube flange connection joint in elasto-plastic phase and yield-hardening phase is carried out, and a three-stage bearing capacity calculation theory of the joint in the seismic process is proposed, which was verified by the test and FEA. •The installation of a core tube can improve the stiffness of the connection area and enhance the coordination of deformation between the upper and lower column;•The separated core tube flange column connection has similar connection properties to weld connection;•The force mechanism of the separated core tube flange column connection joint is analyzed using experiments and finite element analysis;•A three-stage force mechanism model is proposed based on experimental results and numerical analysis of the finite element model.