Abstract: In order to examine the effect of reinforced ring plate on seismic performance of concrete filled steel tubular (CFST) T-joints with spherical-cap gap in CFST chords, a series of hysteresis tests were carried out on 12 CFST T-joints with the chord under constant tensile load and the brace subjected to cyclic axial loading. The performance of CFST T-joints was experimentally investigated in terms of the failure mode, load-displacement hysteresis relationship and strain development. The effects of chord-to-brace diameter ratio and diameter-to-thickness ratio of the CFST chord on the hysteretic behaviour of joint specimens were compared and analyzed. It was found from the test results that the reinforced ring plate could restrain the development of plastic deformation of the CFST chord with spherical-cap gap, and counteract the unfavorable influence on the bearing capacity, stiffness, ductility and energy dissipation capacity of the CFST T-joints caused by the gap. The bearing capacity of the reinforced joint specimen was more than 12.6% higher than that of the specimen with gap but without reinforcement, and it was even more than 6.5% higher than that of the specimen without gap. It was evident that with reasonable design of the reinforced ring plate, the unfavorable influence on the seismic performance of CFST T-joints induced by spherical-cap gap might be fully compensated.