Sensitivity analysis and probabilistic performance assessment of transmission tower-line systems subjected to downbursts

Abstract

Transmission tower-line systems (TTLSs) featured by large span and strong flexibility are particularly sensitive to wind loads. Since the wind field characteristics of downbursts are different from atmospheric boundary layer winds, existing design methods are insufficient to study the ability of TTLSs to resist the effects of downbursts. This study performs the sensitivity analysis and probabilistic performance assessment of a TTLS under downbursts. Initially, a finite element model of the TTLS is established considering tower-line coupling effect. Fluctuating effect and spatial correlation effect are incorporated to generate downburst wind speed time histories for multiple target points. Several key parameters of the downburst wind field model subsequently are selected for sensitivity analysis of the wind-induced responses of the TTLS. Furthermore, a fragility analysis of the TTLS under downbursts is conducted. The results indicate that special attention should be given to the impact of the maximum wind speed in the vertical wind profile. When the wind speed reaches 51 m/s and 45 m/s, the probabilities of collapse and windage yaw reach 50%. This study contributes to providing support for addressing the threats posed by extreme meteorological disasters to TTLSs.