Research On Ultimate Load Capacity And Hysteretic Behavior Of Tubular N-joint Based On The Effect Of The Damage

Tubular intersection joint is an important joint in tubular structure. It has many advantages, such as saving the steels, having a large load capacity and so on. At present, the theory on plane circular tubular joints is mature, and there are also some specifications in the code. Due to little research and experiments focusing on N-joint, it is necessary to do specific research on the ultimate load capacity and hysteretic behavior of N-joint.Based on the consideration of steel structural damage effect, the efficient and accurate N-joint joint finite element model has been established. The model of the different parameters has been established to study the influence of N-joint in the static and cyclic loading. For all kinds of parameters, the study get the following conclusions: Under the action of the static, N-joint occurs two failure modes in charge of local buckling and overall pressure destruction.Values of the parameterβandγincreases, the stiffness and value of ultimate bearing capacity is increase. The value of the gap ratioη, tube angleθand axial load ratio f (n) increases, the ultimate strength and stiffness values of the size of the joint is lower.In cyclic loading and the elastic range, the load and displacement of N-joint is linear, hysteresis curve Quxian overlap, envelope area is almost zero and deformation energy for the elastic strain energy is almost no energy consumption. When the inelastic range cyclic loading in the same magnitude circulation process, the displacement of the displacement after twice is smaller than the first load load value, indicating stiffness degradation. Meanwhile, the same displacement magnitude, the hysteresis loop area surrounded by a slight decrease in energy dissipation capacity of joints can be seen in the sequential degradation. Parametersβandγincrease, making fuller hysteresis curve, ultimate strength, stiffness and ductility coefficient and energy dissipation factor were increased. The lager joint ofβandγcan improve the plastic deformation capacity of joints to improve the energy capacity of joints. The values of parametersη,θand f (n) increase, making hysteresis loop area, stiffness and displacement ductility was significantly lower. The value ofη,θand f(n) weakened plastic properties of the joint, reducing joint energy dissipation. And when the axial ratio exceeds 0.3, the joint capacity, hysteretic behavior and ductility decrease very rapidly. The joints tend to brittle failure. This paper analyzes and summarizes the changes in these parameters impact on the joint. Finally, the subject of further research is discussed.