I. Introduction
At present, the vast majority of transmission line towers above 110kV in China adopt all steel structure [1]. In the construction of transmission lines, there is a great demand for steel, which consumes a lot of mineral resources. The production and processing of steel will also cause certain pollution and damage to the ecological environment. At the same time, the steel has the disadvantages of heavy quality, easy corrosion, poor low temperature performance and so on [2], [3]. Under special conditions, there are problems such as wide line corridor, relatively difficult construction, transportation and operation and maintenance, and the all steel structure tower also has the risk of wind bias discharge and tripping due to lightning and pollution flashover [4].