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Qingdao Maotong ® Power Tower Co., Ltd. is a factory dedicated to the production and installation of steel tower masts and various steel structures such as Electrical Steel Tangent Suspension Electric Line Tower, chimney tower, lightning protection tower, anemometer tower, training tower, roof process tower, single tube tower, bionic tree, integrated base station, communication tower, monitoring tower, power tower, TV tower, Monople Single Tubular Electric Pole Tower, etc.

The majority of steel pipe poles are used on the roads in cities and suburbs. Therefore, the terrain is generally flat or in the terrain with relatively gentle undulation. A value of 0.8 can better meet the span planning, depending on the situation.

Note

1: When you are planning to calculate the span, you should fully consider whether it is a tension steel pipe pole or a suspension steel pipe pole.
2: If it is the length of tension steel pipe rod insulator string, the data brought in should be 0. λ=  0

3: Be careful γ It is the meteorological condition corresponding to the maximum sag. It is not necessarily the dead weight specific load, but also the dead weight plus ice weight specific load.

Horizontal span

The horizontal span (also called wind span) is used to calculate the wind load of the tower, which is generally 1.1~1.4Ls, and 1.1 for steel pipe poles.
We all know that the force of the tower can be analyzed through the three-dimensional coordinate system, in which the direction along the line is called longitudinal (Y direction), the direction perpendicular to the line is called transverse (X direction), and finally the plumb direction is called Z direction. The horizontal load is the force condition of the tower in the X direction.

We usually need to check the allowable horizontal span of the tower during design.

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Vertical span

The vertical span (also called vertical span) is used to calculate the vertical load of the tower, which is generally 1.2~2.0Lh, and 1.2 for the steel pipe pole;
In fact, in engineering practice, it is also taken that the horizontal span is increased by 50~150 meters as the vertical span, but this situation is rare, and it is generally analyzed according to the specific situation.

We can understand the vertical span in this way: a person can carry a shoulder pole easily when the weight is appropriate. If the weight exceeds the limit of this person, it will be crushed.

safety factor

After talking about the span, the next thing to say is the safety factor: the safety factor is an important basis for determining the force on the tower and locating the sag.
This is mainly determined by the electrical specialty according to the positioning situation. In order to simplify the calculation, the safety factor of the angle iron tower or steel pipe tower conductor is generally 2.5; The safety factor of steel pipe pole should not be less than 4; The ground wire safety factor of 110kV universal design steel pipe pole of State Grid Corporation of China is 7.0~8.0.
I have adopted the value of 2.5 in the relocation project, but I will encounter the situation that the isolated span can not meet the requirements of the stringing sag during the stringing process, and even the cross arm has been deformed.
I have also done a lot of analysis and research. According to the analysis, the main reasons are:

The cross arm of the steel pipe pole is a cantilever structure, and the contact area between the cross arm and the pole body is relatively small. Even though the theoretical strength meets the requirements, the rigidity of the cross arm may not meet the requirements; The specifications for the rigidity of the cross arm have not given clear requirements, which are based on the fact that no deformation occurs in the visual and sensory aspects.