Seismic evaluation and calculation models of CFDST column blind bolted to composite beam joints with partial shear interaction

With the purpose of investigating the seismic performance and failure mechanism of the concrete filled double skin steel tubular (CFDST) column blind bolted to composite beam joint with partial shear interaction, an experimental campaign was carried out to assert the effects of end plate type and column hollow ratio. Each specimen was tested subjected to cyclic lateral loads. Typical failure modes of this novel joint in conjunction with the application of partial shear interaction were examined. Based on the experimental results, the crack patterns of steel bar truss deck (SBTD) concrete slabs and hysteretic performance were also estimated. Shift of the beam neutral axis was evaluated by the analyses of the strain distributions. Furthermore, calculation models of the blind bolted composite connections to circular CFDST columns with partial shear interaction were developed based on the component method, where the sagging and hogging moments were both incorporated. For partial shear joints, the shear connector was identified as an important component to estimate its influence on the initial stiffness and moment resistance. In addition, the lower bound of the degree of shear connection was proposed to avoid the shear connector fracture under sagging moment. The predicted results from the proposed component-based models were validated by the experimental data, which demonstrated that the derived calculation models were capable of evaluating the initial stiffness and moment resistances of the CFDST column blind bolted joints to composite beams with partial shear interaction. The experimental and analytical results provide a reference for the analysis and design of blind bolted composite joint to CFDST column with partial shear interaction in engineering practice.