Ultimate Strength Of Steel Tubular K-joints With Gusset Plate Connections Considering Negative Eccenticcity

In order to reduce the energy losing and increase the capability of transmission line,the ultra-high voltage transmission line has been widely applied in these years. Compared to the steel angle tower, the steel tubular tower is applied commonly much more in the ultra-high voltage transmission tower and large span tower because of its good mechanical properties. At present, the tube-gusset joint type is applied mainly owing to the convenience of construction. The K-joints is the most common form of joints. On the one hand, The mechanical behavior of K-joints with tube-gusset plate connections r is complex; On the other hand, The K-joints are abound in practical engineering because of construction requirements.The connections with negative eccentricity is likely to increase the ultimate bearing capacity of joint and decrease the geometry size of gusset plate. At present it must be pointed out that there is a little study about the tube-gusset joint, nevertheless, the research of the tube-gusset joint considering negative eccentricity is not more than that of tube-gusset joint, or even less. The behavior and strength of tube-gusset joint was explored primarily and the following researches are performed:(1) Full-scale tubular K-joints with tube-gusset plate connections were constructed and tested under static loads in this paper. There are 12 experimental specimens. The failure modes and failure mechanism was analyzed. With the reference for the experimentation, finite element model was built.The feasibility of the model is verified by comparing the result of the trial with Finite Element Analysis.(2) The failure modes were analyzed more deeply through a numerical analysis. It is in various kinds of failure modes that the sensitive analysis of major parameters which maybe affect the joint's ultimate strength was carried out. In the kind of the overall instability of the main post, the parameters of affecting the ultimate strength of main post were analyzed, including the axial force of the main post, the force of the bracing member, eccentricity ratio, aspect ratio of the main post and the thickness of the main post etc. In the kind of the local buckling of the joint, the parameters of affecting the ultimate strength of the joint were also analyzed, including the axial force of the main post, the force of the bracing member, eccentricity ratio, the diameter of main post, the length of gusset plate, the thickness of main post, the thickness of stiffening rib and the width of stiffening rib etc. (3) In the kind of the overall instability of the main post, The equivalent force model was built and the proposed formula of ultimate strength considering eccentricity was obtained. In the kind of the local buckling of the joint, suggesting formulas for the strength of tube-gusset joint, axial brace forces are replaced by equivalent force model. Non-dimensionalized ultimate strength interaction relations between the wall moment of tube, vertical axial force, and eccentric vertical component force of axial brace force were formulated through parametric study.