Ring Mouth Board To Strengthen The T-round Tubular Hysteretic Behavior

For a circular tube member, its radial stiffness is generally much smaller than its axial stiffness due to its hollow section and thin wall. In a welded tubular joint, the brace is mainly subjected to axial load, which causes the chord to be subjected to radial load. Furthermore, high stress concentration exists at the joint because the curvature is uncontinuous. Because of the above reasons, the common failure mode for a tubular joint is local buckling or yielding on the chord surface near the weld toe.In order to increase the stiffness of the chord and to improve the bearing capacity of the tubular joint, collar plate reinforcement is adopted to strengthen the tubular joint. Collar plate reinforcement is a new reinforcing method for tubular joints, and it is of fast fabrication and of markable efficiency. To carry out 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 specimens reinforced with collar plate under quasi-static axial cyclic loading is carried out experimentally. Based on the experimental results, it is found that both the static strength and the ductility are increased for the reinforced specimens, and thus the reinforced T-joints can dissipate more energy caused by seismic action. 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.Thereafter, the finite element (FE) analysis on the above 8 specimens are conducted. The numerical results agree with the experimental results well, and the presented FE model is proved to be accurate enough for analyzing the hysteretic performance of T-joints with collar plate reinforcement. The effect of the reinforced parameters, namely tc and lc, on the hysteretic performance of the T-joints with collar plate reinforcement are studied based on a parametric study and suggestions for choosing the reinforced parameter values are given. Comparing the enhanced effects of lc and tc, it is found that the second model is more effective than the first model. The results are significant for the design of collar plate reinforcement for tubular joints in practical engineering.