Shan According to structural materials can be divided into wood structure, steel structure, aluminum alloy structures and reinforced concrete structure of several towers. Because of its low strength, short life span and limited maintenance, the timber tower has been eliminated in China. Steel structures are divided into trusses and steel pipes. Lattice truss towers are used most, and are the main structures of ehv-above lines. The aluminum alloy towers are used for transporting particularly difficult mountainous areas because of their high cost. The reinforced concrete poles are made of centrifugal machine and steam curing. Its short production cycle, long service life, simple maintenance, but also to save a lot of steel. The concrete pole with partial prestress technology can prevent the crack of the pole and the quality is reliable. China uses the most and occupies the top of the world.
Shan according to the structure of the form can be divided into free-standing tower and guyed tower two categories. Self-reliance Towers are built on their own basis to stabilize the towers. The Guyed tower is installed in the tower head or tower body symmetrical pull line to firmly support the tower, the tower itself only bear vertical pressure. This tower saves nearly 40% of steel, but the distribution of the tillage is unfavorable to the agriculture and forestry industry, and the scope of use is limited. Because the mechanical property of Guyed tower is good, it can resist storm attack and the impact of line disconnection, the structure is stable, so the higher the voltage, the more the line application of Guyed tower. Quebec, Canada, has a new type of suspension tower on the 735,000 kv line, which has a good economic benefit. In the study of more than 1 million kv lines, the main object is the tower type.
The Shan can be divided into Lita, linear tower, transposition tower and large span high tower by using function. The circuit number of transmission lines erected by the same tower can be divided into single return, double return and multiple loop towers. The load-bearing tower is the most important structural link in the transmission lines. It is segmented to set up, the wire resistance of the insulator string anchor hanging on the tower, bearing both sides of the wire, grounding wire tension and the uneven tension of the accident. This kind of tower is convenient for sectional construction and can restrict the range of accidents in operation. The load-bearing tower can be divided into jumper, corner towers and terminal towers. The linear tower is the most used structure on the line. It only undertakes the suspension of wire, ground wire and meteorological load. The technical design data of the straight tower is the key to determine the economic index of the whole line. The transposition tower is a tower which realizes the conductor transposition so as to balance the transmission line parameters. China takes the $number kilometer as a whole cycle transposition segment (some countries have 200 kilometers of the line without transposition). Large span towers (see chart) refer to large spans of rivers that straddle navigation. This will avoid the installation of the tower in the river in a series of inconvenience (such as complex design, foundation construction costs, long duration, etc.), usually designed double circuit across the line. Around 90 of the world's 220,000-volt, 1000-metre-high spans, China has 10. In China, the first use of reinforced concrete chimney type tower (spanning tower of Wuhan across Yangtze and Han River), low steel consumption index and convenient operation and maintenance. Later, the use of steel tube tower (Nanjing across the Yangtze River, 193.5 meters high), guyed Steel Tower (Huangpu across the Pearl River, 190 meters high).