Steel pipe tower is also named tubular tower and steel tubular tower.It refers to a lattice tower made of steel pipe or section steel. The steel pipe tower is a kind of supporting structurion that overhead the transmission line and used to support the conductor and the lightning conductor.Steel pipe tower make the wire meet the requirements of the distance limit to the ground,and steel tubular tower is used to bear the load and external load of the wire, the lightning conductor.
The main feature of steel pipe tower :
The steel tube tower structurion has relative technical and economic advantages, and it is suitable for use in transmission towers that bear heavy loads.
(1) Load characteristics
The load characteristicssteel of pipe tower rods as follow:low wind pressure, high flexural rigidity, simple structure, and clear force transmission, and steel pipe tower can fullly show the bearing performance of the material. On the one hand, it can reduce the weight of the tower and reduce the foundation force; on the other hand, on the other hand, it is also beneficial to enhance the ability of steel pipe tower rods to resist natural disasters under extreme conditions. In the case of meeting the requirements of strength and stability calculations, the use of steel tube towers with relatively small wind pressure body coefficients can significantly reduce the wind load on the tower body.
(2) Sectional characteristics
The cross-section of the steel pipe parts is symmetrical in the center, and the cross-sectional characteristics are isotropic; the material is evenly distributed around the periphery, and the cross-section has a large bending stiffness. For the tension member of the transmission tower, when the cross-sectional area of the steel pipe and the angle steel are equivalent, the steel pipe tower member does not show its advantages. As for the bending members of the transmission tower, the use of steel pipes with a smaller cross-sectional area and a larger radius of gyration can fully exert the mechanical properties of the material in a balanced manner, and meet the requirements of structural rigidity and stability, especially for larger structural geometrical dimensions and larger rods. The advantages of steel tube tower are obvious,such as:long, heavy-load steel towers and steel pipe towers with good stability.
(3) Construction connection
In terms of structural connection, the main material of the steel pipe tower adopts flange connection or intersecting connection, the oblique material and the main material adopt plug-in connection or intersecting connection, and the main material of angle steel tower adopts inner or outer connection. They are mainly connected by connecting plates and bolts. The connection structure of the flange and the plug-in plate of the steel pipe tower is relatively simple. Although it increases the welding workload, it reduces the adverse effect of the eccentricity of the angle steel member on the structural load-bearing performance, and at the same time enhances the rigidity and compactness of the connection node, which helps To improve the overall rigidity and stability of the structure and the ability to resist wind vibration loads.
The development of steel tube tower
Compared with foreign countries, the steel materials used in the structure of transmission towers in China have a single variety and small options.
With the continuous development of China’s metallurgical industry, the production of high-strength steel is no longer difficult. The quality of China’s high-strength structural steel has improved rapidly and is becoming more stable, and the supply channels have become smoother. High-strength steel is used for transmission line towers. Steel offers the possibility. In the preliminary scientific research project of the 750kV transmission line, the Electric Power Construction Research Institute of the State Power Corporation has conducted research on the connection structure of the nodes, the value of the component design parameters, the supporting bolts and the economic benefits that will be encountered in the use of high-strength steel: In use, high-strength steel has fully equipped the conditions for use in iron towers, and the use of high-strength steel can reduce the weight of the iron tower by 10%-20%. But the biggest obstacle to the mass use of high-strength steel is the supply of section steel materials. The steel tower requires a wide variety of section steel, and the batch demand for each specification is not large. At the same time, high-strength section steel is difficult to form, the cost of rolling die is high, and roll adjustment is difficult, making steel mills less enthusiasm to produce high-strength section steel and difficult to guarantee supply.
The applicantion of steel pipe tower
In the 1980s, with the development of UHV transmission lines in the world, steel pipe profiles began to be applied to tower structures, and a kind of steel pipe towers that with steel pipes as the main material of the tower body appeared. In Japan, steel pipe towers are almost all used in 1000kV ultra-high voltage lines and high towers.
Drawing on foreign experience, domestic steel pipe profiles have also been used in 500kV double-circuit towers and four-circuit towers on the same tower, which demonstrates its good performance and benefits. Due to its large section stiffness, good section stress characteristics, simple stress, beautiful appearance, etc., the steel pipe tower structure has been well developed in lines of different voltage levels. Especially in large-span structures and urban power grid tower structures.