Seismic performance of high-strength anchor rebar column-foundation connection for CFST

The anchor rebar column-foundation connection (ARCFC) is proposed for concrete filled steel tube (CFST) column to simplify the construction process of column-foundation connection. In this paper, a total of eight specimens were tested to failure under constant axial load and cyclic lateral load. The influences of reinforcement ratio, configuration of shear hoop rings, and axial load ratio on the seismic performance of ARCFCs are experimentally investigated. The failure mode of all the specimens is characterized by bending, and no tube local buckling was observed in the tested specimens except for the embedded connection. Experimental results show that all the specimens have good ductility with ductility coefficients larger than 4.5. Analysis is conducted to investigate the influence of test parameters on the load-displacement skeleton curves, stiffness degradation, energy dissipation capacity, and strain development of steel tube and anchor rebars. Analysis results reveal that the seismic performance of the proposed connection is similar to the embedded connection when it is designed according to both the “compression equivalence” and “bending equivalence” principles. Based on the test results, a calculation method for the sectional strength of the bottom section is suggested and verified.