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:In order to reduce the energy loss 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 transmission tower, the steel tubular tower has better mechanical properties and wind-resistant performance, it was widely used in ultra-high voltage transmission tower and long span transmission line. In the design of connection in steel tubular tower, the tube-gusset plate type is more common, its mechanical property directly affects the safety of the transmission tower,especially the stability of structural strength.With the increase of transmission voltage, transmission tower height continuously improve,the load of it bears will be much more, the mechanical properties will be more complicated. However, at present, the study of mechanical property is not deep enough, the domestic and foreign norms does not make detailed provisions for the ultimate bearing capacity, the calculation method that used for practical engineering design is lacking. In view of this phenomenon, the mechanical performance of K-type tube-gusset joints based on the negative eccentricity was studied in experiment and theory in this paper, the following aspects are the major objectives of the study:(1) Four tube-gusset plate connections with various gusset plate、eccentricity、axial compression ratio were tested under the ultimate strength loading, the failure process and pattern were studied, analyse the mechanical behaviors under different design parameters. Finite element analysis was conducted to experimental model, the effectiveness of finite element model was verified, the influence law of ultimate strength considering eccentricity、annular plate、axial compression ratio was studied.(2) Develop advanced FEA model and analyze the influence of various parameters such as the diameter of main pipe, the length of gusset plate, the thickness of main pipe, annular plate, the axial compression ratio and other parameters on the ultimate strength of tube-gusset joints.(3) On the basis of the simplified model, fit the formula of the main tube axial load、the wall shearing force ultimate value and the wall moment, comparing with the domestic and foreign research achievements, the applicability of the fitting formula was verified. Finally, interaction relationships between the vertical axial force, wall moment of tube, and eccentric vertical component force of axial brace force were formulated through parametric study.
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