Transmission line tower is a kind of tower-shaped buildings for power transmission. Transmission line tower structural characteristic: every tower type is space truss structure. The lever of transmission line tower mainly composed of single equilateral angle or combined angle steel. The materials of transmission line tower are generally Q235 (A3F) and Q345 (16Mn). The connection between the levers is thick bolt and the bolts are connected by shearing force. The whole transmission line tower is composed of angle steel, connecting steel plates and bolts, and individual components such as tower feet are welded into a combination by several steel plates. Therefore, it is extremely convenient for the hot-dip galvanizing anticorrosion, transportation and construction erection. For the iron tower whose height is below 60m, set foot nails on one of the main materials of the iron tower to facilitate the construction workers to climb the tower.
◪In recent years, with the rapid economic growth, the power industry has developed rapidly, driving the rapid development of the transmission line tower industry. According to statistics, the sales revenue of Chinese transmission line tower industry increased from 5 billion yuan in 2003 to 42.6 billion yuan in 2010, with a compound annual growth rate of 36.68%. The transmission line tower industry is in a period of rapid development. In 2010, Chinese transmission line tower industry showed a good development trend, and enterprises in the industry had a higher ability to manage and control costs and profitability.
◪At the end of 2010, the number of large-scale transmission line tower enterprises is more than 252 in China,and the total assets reached 32.25 billion yuan, an increase of 25.55% year-on-year. In 2010, the Chinese iron tower industry total industrial output achieved at the value of 43.31 billion yuan, an increase of 25.36% year-on-year.The sales revenue of iron tower industry was 42.591 billion yuan, an increase of 29.06% year-on-year.And the total profit of iron tower industry reached 2.045 billion yuan, an increase of 43.09% year-on-year.
◪During the "Twelfth Five-Year" period, China increased investment in power grids, with an investment of about 2.55 trillion yuan, accounting for 48% of the total investment in electricity, an increase of about 3.0 percentage points from the "Eleventh Five-Year" period.From 2011 to 2012, the annual compound growth rate of chinese transmission line tower industry sales revenue was 28%.With the continuous increasing investment,The demand for transmission line towers is also increase, and the development prospect of the transmission line tower industry is broad.
Types of transmission line tower
According to the shape of transmission line tower, transmission line tower is generally divided into five types: wine glass type, cat head type, upper font type, dry font type and barrel type.
According to the use, there are tension tower, linear tower, corner tower, transposition tower (replace the wire phase position Tower), terminal tower and span tower.
According to the use of pole towers in power transmission lines, transmission line tower can be divided into linear pole towers, tension pole towers, corner pole towers, transposed pole towers, spanning pole towers, and terminal pole towers.
According to the structural material classification of pole towers, pole towers used in transmission lines mainly include reinforced concrete poles and iron towers.
According to the terms of maintaining the overall stability of the structure, transmission line tower is divided into self-supporting towers and cable-type towers.
The structure of pole towers is various. From the perspective of the transmission lines that have been built in China, iron towers are often used in transmission lines with voltage levels greater than 110kV.Reinforced concrete poles are often used when voltage levels are less than 66kV. The tower cable is used to balance the lateral load and wire tension of the tower, reduce the bending moment at the root of the tower, and use the cable to reduce the consumption of tower material and the cost of the line. On the path of flat terrain, the use of cable towers is more common. The selection of the type and shape of the tower should meet the electrical requirements and meet the voltage level, number of circuits, terrain, geological conditions, etc. of the transmission line, and select the form of the tower suitable for a project according to the actual situation. Through economic and technical comparison Finally, choose the type of tower with advanced technology and reasonable economy.
Structure of the iron tower
The whole iron tower is mainly composed of three parts: tower head, tower body and tower legs. If it is a wire-drawing iron tower, the wire-drawing part is added.
◪Tower head: From the tower legs to the top, the section of the tower changes abruptly (a broken line appears). The upper part is the tower head. If there is no abrupt change in the section, the upper part of the lower chord of the lower crossarm is the tower head.
◪Tower legs: The first section of the tower above the foundation is called the tower legs.
◪Tower body: The part between the tower legs and the tower is called the tower body.