Seismic Behavior of Blind Bolted CFST Frames with Semi-rigid Connections

To investigate seismic behavior and failure modes of blind bolted concrete-filled steel tubular (CFST) frames with semi-rigid connections, an experimental study on two specimens of two-layer single-span blind bolted end plate CFST frames was conducted under low-cyclic loading. Both the end plate type and the loading type were taken into consideration in this paper. The seismic behavior of the overall composite structures was analyzed and evaluated in terms of the hysteretic behavior, failure modes, stiffness and strength degradation, ductility, and energy dissipation capacities. Some simplified models were proposed in this paper to predict initial stiffness and moment capacity for blind bolted end plate joints to CFST columns. It was concluded that the blind bolted CFST frames with semi-rigid connections exhibited large hysteretic loops, good ductility, and excellent energy dissipation capacity. These studies enable improvement in the practical design and application of semi-rigid CFST frames in seismic regions.