Research On The Stability Of UHV And Ultra-High Tower

Research on a transmission tower with height of 198m and spanning distance of 1200m is the background engineering in this article.Because of the complex environment of transmission tower, many types loads apply on the structure such as wind、gravity、seismic and icing load.The wind load is the major factor attributed to structure stability.Nonlinear analysis of tower structure is furthered based on the existed results under wind load.For background engineering types of tower selection are compared.The main research of this paper are:dynamic characteristics analysis of transmission tower and the tower-line system are conducted Considering the P-Δ effect the wind load response of transmission tower is analysed using equivalent static analysis. The elastic buckling safety factor,structural buckling mode and the formation of instability rod are obtained through analyzing the using stage of tower.Ultimate bearing capacity of tower and tower-line system are studied based on established nonlinear analysis model.Single tower modal analysis shows that the first horizontal vibration mode is likely the buckling load direction.Nonlinear buckling analysis is done based on elastic buckling analysis result considering large deformation、the initial flaw and material nonlinear constitutive model.The tower structure become instable when root bar reaches yield stress at wind speed of 68m/s.The ultimate bearing capacity of the structure reduces considering the fluctuating wind speed.Buckling analysis and dynamic characteristics of the structure considering the second-order effect of tower-line system are done after form-finding analysis. Vibration period of structural system increases by 27.6% and the ultimate wind speed decreased to 48m/s because the wires are flexible structure and has some impact on the system.