Seismic performance of the concrete-encased CFST column to RC beam joint: Experiment

The concrete-encased concrete filled steel tubular (CFST) column to RC beam joint is composed of the concrete-encased concrete filled steel tubular (CFST) column and the reinforced concrete (RC) beam. Concrete-encased CFST column consists of a CFST component and an outer reinforced concrete (RC) component. This paper presents an experimental investigation of the seismic performance of this kind of composite joints. Thirteen joints were tested under a constant axial load on the column and a cyclic vertical load on the beam. The test parameters include the joint types, the connection types, the axial load level, the joint core volumetric stirrup ratio, the beam longitudinal rebar ratio and the sectional dimension of the beam. Four types of typical failure modes are found, and the corresponding hysteretic relationships are analyzed based on the test results. The seismic performance of the composite joint is also evaluated by several indexes, such as rigidity degradation, strength degradation, ductility, and energy dissipation. Finally, a comparison with other typical joints is conducted to exhibit the seismic performance of the concrete-encased CFST column.