Flexural Capacity of Cross-Shaped Concrete-Filled Steel Tubular Column–Steel Beam Joints with Side-Plate Connections

The application of connection joints between a cross-shaped concrete filled steel tubular column and a steel beam can improve the seismic performance, which also provides an effective way for saving building space. In this paper, models and flexural capacity of the connection joint with and without side plates were designed and evaluated, respectively. A refined mechanical analysis model of a joint subjected to low-cycle reciprocating loading was established using the finite element software ABAQUS. The failure characteristics of the joints with and without side plates were compared. The influence of axial compression ratio, side plate height, and side plate thickness on the flexural capacity of joints with side plates was studied. Moreover, the failure mode and force transfer mechanisms of these joints were analyzed. Based on the results of the finite element analysis (FEA), the ultimate tensile capacity of the steel tube column flange to the steel beam was calculated according to the yield line theory; the tension transmitted by the side plate was simplified for calculation via the static equilibrium method. Subsequently, the formula for calculating the flexural capacity of the joint with side plates is established. The results show that the ultimate bearing capacity of the joint was increased by 41.5% due to side plates effect, which decreased with an increasing axial compression ratio. Moreover, the ultimate bearing capacity of the joints increase slightly with an increase of height and thickness of the side plate, and the maximum increase was only 6.2%. In addition, the calculated results obtained by the proposed formula of ultimate flexural capacity are consistent with the results of the FEA.