Abstract: Collar plate reinforcement is a new reinforcing method for tubular joints, and it is of fast fabrication and effective. To carry out further study on the behaviour of tubular joints after reinforced with collar plate, the hysteretic behaviour of 4 full-scale un-reinforced tubular T-joints and 4 corresponding T-joint specimens reinfoced with collar plate under quasi-static axial cyclic loading is investigated experimentally. Based on the experimental results, it is found that both the static strength and the ductility are increased for the reinforced specimen, and thus the reinforced T-joint can dissipate more energy caused by seismic actions. It is also found from the experimental phenomenon that the failure position is located at the corner of the collar plate, which is much different from the un-reinforced specimen for which the failure position is located at the weld toe along the brace/chord intersection.