Structural health monitoring oriented stability and dynamic analysis of a long-span transmission tower-line system

Structural stability is an vital aspect for structural health monitoring of transmission lines. This paper presents a novel method to evaluate the structural status of transmission line based on dynamic and stability analysis. A newly built long-span transmission tower-line system that crosses the Huaihe River in China with a span of 1083 m was studied as an example. Finite element model of the transmission tower-line system was constructed. Nonlinear buckling analysis for both the tower and tower-line system were performed to determine the critical wind loads. Dynamic properties of both the tower and tower-line system under different levels of wind loads were analyzed. Numerical results show the law that modal frequency of low order modes decreases when the wind velocity increases before the structural instability happens for both cases. Therefore, for the structural health monitoring of transmission lines, frequency decrease of low order mode is an useful indicator to predict the happening of structural instability. This conclusion could be taken as the reference in the design of structural health monitoring system for transmission lines.