Behaviors And Ultimate Strength Of Steel Tubular K-Joints With Gusset Plate Connections In Uhv Transmission Tower

The transmission tower is flexible due to the large height of ultra-high voltage transmission tower and large span tower, thus the internal force is controlled by all load at a certain extend. Compared to the steel angle tower, the steel tubular tower is applied commonly much more because of its smaller windward area, bigger cross-section gyration radius .At present, the tube-gusset joint type is applied mainly owing to the convenience of construction. But there are just a few scholars home and abroad to research the tube-gusset joint which resist complicated force and there are some irrationalities in the theory existence at present. 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 are constructed and tested under static loads.The failure modes and failure mechanism are analyzed.Based on experimentation and FEM , tubular energy theory about the ultimate strength of K-joints was deducted and a limit analysis model for determining the ultimate loads of tube-gusset plate connections is established using ring-generator separation model.In this model, tubular and ribbed-plate were considered and the model reflected the development of the plastic range of K-joints and simplified the performance of mechanics. This paper proposes the calculation method of the ultimate strength of the tube-gusset K-joint under different failure modes.It reveals that the method has theoretical and practical significance for design.(2) The parameters which influence the ultimate strength of gusset-plate and the failure type of the plate was analyzed roundly based on a mass of full size model experiment data and FEM. The failure modes and failure mechanism were analyzed about the plate.The ultimate strength of plate depends on width-thickness ratio, non-limb length and conformation of the plate.The proposal calculation method of the ultimate strength of the plate was put forward based on an inelastic plate buckling equation .The plate was ribbed in the middle part and along splice member,which can alter the failure model and the invalidation avenue and improved the ultimate strength of the plate. Adding free edge stiffeners can increase the buckling strength of gusset-plate connections efficiently.(3) A numerical analysis and experimental study were performed to investigate the behavior and strength of tube-gusset connections subjected to axial and axial brace force. The parameters which influence the ultimate strength of tube-gusset joint and the failure type of joints was analyzed. To suggest a formula for the strength of tube-gusset joint, axial brace forces are replaced by equivalent wall moment and eccentric vertical component force of axial brace force. 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.