Research On Bearing Capacity And Stiffness Of KKX-type Circular Steel Tubular Joints

Nowadays, the KKX tubular joints have been widely used in space tubular structure,however, when the joint is applied to large span or super large span of space structure, it will bring the following problems. Firstly, along the span direction, the change of internal force which is so large that a great waste of material will be caused if the chord section remains unchanged. Secondly, due to the large span, the diameter of the belly bar is relatively large, if the diameter of the chord is not increased, it is difficult to realize the welding of the welding arc when the belly bars intersect in the joints directly. As for these reasons, a new joint of KKX hollow straight pipe cone joint was presented to achieve the goal of saving consumption of steel and improving the construction performance of the joints by the professor Kejian Ma.In order to facilitate the engineering application of KKX tubular joint and KKX hollow straight pipe cone joint, the research focuses on the influence of ultimate bearing capacity and joint rigidity caused by the geometry parameters of the joints through the parametric analysis from the software of ANSYS. The analysis shows that:(1) For the KKX tubular joint, he diameter and thickness of the main pipe, the diameter of the chord and belly bar, the angle between main pipe and belly bar, the ratio between the gap of two belly bars and the diameter of the main pipe, the ratio between the axial forces applied to the main pipe and the standard value of the yield load, the ratio between the axial forces applied to the chord and the standard value of the yield load have significant effects on the ultimate bearing capacity and joint rigidity of the joints. At the same time, the increase of the thickness of the belly bar can improve the joint rigidity effectively, and have a little influence on the ultimate bearing capacity.(2) For the KKX hollow straight pipe cone joint, he diameter and thickness of the joint pipe and the belly bar, the diameter of the third chord, the angle between joint pipe and belly bar, the angle between the two belly bars, the ratio between the gap of two belly bars and the diameter of the main pipe, the ratio between the axial forces applied to the third chord and the standard value of the yield load have significant effects on the ultimate bearing capacity and joint rigidity of the joints. Meanwhile, the increase of the thickness of the second chord can improve the joint rigidity effectively, and have a little influence on the ultimate bearing capacity.(3) The formula of KKX tubular joint and the KKX hollow straight pipe cone joint were presented by the influence coefficient ?f to amend the KK joint of the ultimate bearing capacity of the calculation formula based on the code for design of steel structure. This formula has considered the influence of different parameters on the bearing capacity of the joint. Based on it, the conception of joint rigidity factor ? and the joint capacity factor ? were presented to get the relation curve of the ?-? for the different parameters. At last the formula of the joint rigidity was proposed by using the multiple linear regression method.