Simulations for tower collapses of 500kV Zhengxiang transmission line induced by the downburst

The current paper investigates a destructive accident of Zhengxiang transmission line, in which there was six-tower collapse that might be demonstrably conducted by the downburst gust. Based on the dynamic stress analysis of tower members under the strong wind, tower collapse procedure is simulated by finite element method. Finite element method together with material nonlinearity, large deformation, contact, etc, is adopted to model the accident transmission line. Implicit and explicit method are both incorporated for the time integration in the dynamic analysis. Since the accident downburst gust have not been detailedly observed, the strong wind model and the simple gust model are experientially specified as the load boundary condition. The calculation results show that, maximum stress values of some tower members exceeds design values under the specified strong wind and then may overload tower members. With the specified downburst load, tower collapses will occur, and the broken-down tower in the simulation is very similar with real one. The introduced numerical models are effective and available to calculate the transmission line accident further.