Numerical simulation on the typhoon-induced dynamic behavior of transmission tower-line system

The spatiotemporal impact of typhoons moving across transmission networks is increasingly evident, which may result in the failure of the overhead transmission tower-line (TL) system. The structural design and safety assessment to transmission TL systems that subjected to extreme winds are necessary. This paper aims to provide fundamental insights on the wind field caused by typhoons as well as the typhoon-induced dynamic loads and responses of the transmission TL system, by means of the numerical simulation. This paper offers a numerical scheme to simulate the typhoon-induced wind field on a TL system, in which the movement of the typhoon center and the nonstationary fluctuation of the wind are concerned. In the scheme, the near-surface mean wind speed is calculated based on the radial profile and translation of storms; the nonstationary fluctuation component is generated by a time-varying modulation function. By applying the simulated wind field to the finite element model of TL system, we yield the dynamic responses of the TL system as well as the dynamic loads resulting from the interaction between the structure and wind. Utilizing the evolutionary power spectral density (EPSD) function, the fluctuating wind loads and structural responses are addressed both in the time and frequency domains. Further discussion is done on the typhoon-induced loads by constructing the dynamic equivalent factors. The time-varying equivalent factors show the stationary process, which demonstrates the fading out of the non-stationarity for simulated wind loads. The comparison result indicates that the gust response factor of tower recommended by design codes may not be safe enough when the typhoon impact is concerned.