Failure analysis of a lattice transmission tower collapse due to the super typhoon Rammasun in July 2014 in Hainan Province, China

Abstract

The failure mechanisms of lattice transmission towers under the extreme wind conditions of typhoons are not well known and such knowledge is important for the improvement of overhead transmission line (OHL) design and to ensure the safe operation of transmission lines in typhoon-prone areas. This paper presents a case study on failure analysis of 13 collapsed lattice transmission towers in a110 kV transmission line during the super typhoon Rammasun that occurred in July 2014 in Hainan Province of China. A systematic computational procedure was developed to conduct the failure analysis with particular focus on modeling the fluctuating turbulent wind loads combined with the heavy rain loads. The results show that the failure mode and location obtained from the dynamic analysis are in good agreement with the post-event field observations. The collapse of the suspension lattice transmission towers was triggered by the buckling of the main leg members in the third panel from the ground level due to the extreme high axial stresses. Key design suggestions like improving the design wind speed and adopting an equal-strength beam approach are proposed to reduce the risk of lattice transmission tower failure and ensure continued serviceability and safe operations under the typhoon-wind conditions.