Mechanical Characteristics and Destroyed Modes for Cross-arm Supporting Ground Wires of UHV Transmission Tower Under Ice Shedding
Affected by the severe accreted ice exceeding design values and impact of ice shedding,the cross-arm supporting ground wires of a typical UHV tensioned transmission tower are bent and damaged.The general finite element software ANSYS is used to establish the finite element model of the ground wire-tensioned tower-fitting string system.Through the geometric nonlinear dynamic time-history analysis under ice shedding cases,the longitudinal unbalanced tension,the vertical load acting on the suspension points as well as the corresponding impact factors are determined for different accreted ice thickness.A refined finite element model of the cross-arm supporting ground wires is established by using the beam and truss element,and the peak load of the ice shedding case is applied to the suspension point.Stress contour of the members of the cross-arm is obtained,and the member location firstly occurred buckling failure is determined.The bending stress of the main member at the second segment is 37.9%of the axial compressive stress,and the influence of bending moment cannot be ignored.The full-scale test of the cross-arm supporting ground wires under the conditions of 30 mm accreted ice and 100%ice shedding ratio at the big-number side is completed.The strain variation trends for typical members during loading are revealed.The original failure location and the failure mode are inversed by full-scale test.The experimental failure mode is basically consistent with the finite element simulation results and the field failure mode.
ice sheddingfinite element analysisfull-scale teststrainunbalanced tensionbending moment at the end
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