Analysis Of The Structure Strength For Flexible Flange Connection In UHV Steel Tube Tower

Transmission steel tube tower with small wind pressure and good bearing performance is widely applied in the long distance transmission line construction. While flange joints are common in electric transmission steel tube tower, its connection reliability, the structural strength and the structural forms have always been an important research topic.The paper takes flexible flange for object of study in the UHV transmission line project. Firstly, the various method of bolt-tightening in the high strength bolt of the flange are studied and discussed, and the optimized preload strategy is put forward in order to improve the connection quality and reliability of flange bolts and flange structural. Secondly, the 3D model of flexible flanges are constructed using FE software ANSYS, strength and deformation are studied in the axial force, which considered the nonlinear contact of the bolt and flange. Then the relationship between a single parameter change and load-bearing capacity is investigated, such as distance between bolts and tube, distance between bolts and edge of flanges, thickness of flanges, bolt number and bolt pretension, which provides the reference for application to the project.According to the above analysis, the following conclusions can be drawn: Compared to one by one bolt preloading way, the symmetrical preloading bolt way is able to improve preload effect of high strength bolt group; Fractional preloading bolt way can improve the residual preloads distribution between different bolts and make contact pressure stress homogeneous distribution; Compared to I-type flexible flange, II-type flexible flange constitution uses the Integral forging method, so its integral stiffness is higher; Some methods can improve the bearing capacity of flexible flange, such as by arranging bolt closer to the tube, increasing the flange thickness and the number of bolts in flange plate; it also can improve the bearing capacity of II-type flexible flange to increasing the neck slope in the reasonable range.