Mechanical behaviour of a new ECC-encased CFST column to RC beam connection under cyclic loading

This paper proposed a new engineered cementitious composite (ECC) ring beam connection for ECC-encased concrete-filled steel tube (CFST) columns. Seven ring beam connection specimens, including two concrete specimens and five ECC specimens, with different reinforcement ratios, ring beam sizes and axial compression ratios, were tested under reversed cyclic loading. The seismic performance of the proposed connection was evaluated in terms of the failure mode, hysteretic characteristics, stiffness degradation, ductility and energy dissipation. Based on the test results, application of ECC in the joint region resulted in a higher load bearing capacity, ductility and energy dissipation than those observed for concrete specimens. The relative reinforcement ratio had a significant effect on the failure modes of the ECC connection. Additionally, the increase in the circumferential reinforcement ratio and joint size had favourable influences on the seismic behaviour of ECC connection. These test results proved the applicability of ECC material in ring beam connection for ECC-encased CFST columns.