Poles
Introduction
We are MREC, the industrial company you need
Poles
Introduction
We are MREC, the industrial company you need
For many years throughout the world, poles made of wood, steel and concrete have been used to support power lines, street lighting, overhead power lines for railroads, and antenna masts. Concrete poles were first used over 60 years ago and were then made of normal reinforced concrete. As technology improved, the production and use of concrete poles gradually increased.
Prestressed concrete poles should not be regarded as novel or new. They were first designed and constructed by the French pre-stressing pioneer Eugene Freyssinet in Algeria in the middle 1930s. It was also Freyssinet who, many years ago, conducted his classic demonstration in which a normal reinforced concrete pole and a prestressed pole, designed to the same ultimate load, were placed in a special testing apparatus and subjected, not only to repetition of a load equal to, but also to alternation of a load amounting to 50 percent of the designed ultimate load. The normal reinforced concrete pole failed at a few thousand repetitions, but the prestressed pole was still going strong at 500,000 cycles. Since this is the type of loading that poles are expected to carry in the field, this test was of significant interest to pole users.
The greatest hazard associated with normal reinforced concrete poles is the corrosion of steel. This leads to spalling of the concrete and, ultimately, the failure of the pole. The corrosion may be caused by insufficient cover, substandard concrete, or excessive tensile forces, hence cracks, in handling or service, owing to poor design or to misuse. Any of these conditions can cause the penetration of water to the steel. The process might take several years, but once corrosion is started, failure years, but once corrosion is started, failure becomes inevitable.
The prestressed concrete pole offers the following advantages:
First, the concrete used is of a quality sufficient to resist penetration of water. Otherwise, the pole could conceivably fail during the pre-stressing operation.
Secondly, in a prestressed pole, the concrete is usually in compression, and cracking is not possible except under abnormal conditions of handling or service.
These characteristics give the prestressed pole greater advantages over the normal reinforced pole and are the reasons for developing and using pre-stressed concrete poles. Today, prestressed concrete poles are widely used throughout Eastern and Western Europe. They are extensively utilized in Japan and to varying degrees in many other countries around the world. Available data indicate that the Soviet Union has produced and used the most poles, whereas the United States and Canada have only recently initiated their utilization.
Spun Concrete pole is superior to the existing concrete or steel poles in the following manner.
Concrete poles are cheaper in the initial as well as cost over its life.
The spun pole has a greater life than any other type of pole.
The spun pole is vandalism proof and is not liable to be stolen or damaged.
The natural smooth finish of concrete is aesthetically pleasing.
It is lighter than equivalent concrete poles but heavier than steel poles. Therefore it is easier to transport than H-Type concrete poles and less liable to be damaged in handling or transportation.
It needs no maintenance ( painting etc ) throughout its life, a conservative estimate of 75-100 years can be taken as its life.
A wide variety of strengths, designs, and lengths are possible by varying the PC wires or concrete thickness/diameters.
It needs no foundation and can be directly embedded in natural soil, resulting in a much cheaper erection cost than steel poles.
Indigenously material is used in the concrete pole, thus saving in foreign exchange.
Round cross-section of the spun concrete pole gives less air resistance than equivalent H-Type poles, resulting in being less stressed in normal working as well as in storms and in windy areas.
Concrete is a non-conducting material thus making it safer to use in many circumstances.
Spun pole can take torsion load as well as shear much better than the H-Type pole which is not designed for these loads.
The natural hollow recess in the spun pole can be conveniently used for wiring etc.
This being a non-metal pole, the disturbances due to earthing and short-circuiting is eliminated.
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