The line of sight for telecommunication antennas may be become obstructed due to:
The buyer must specify the following parameters, before asking for an offer from tower supplier.
For details of structural parameters required to be specified, the answer of Q2 above.
Following could be the further necessary/optional parameters for supply of tower materials.
To achieve desired strength of tower, use of HSS (High Strength Steel) instead of normal mild structural steel will result in lighter tower.
In case of towers, operational costs do not depend on weight of tower. Hence no special advantage is obtained by using HSS.
Not necessarily. It depends on:
Normally not. Some members are designed on the basis of permissible slenderness ratio. These members are not made from HSS. Only few members of tower are made from HSS generally.
As strength of steel increases, the brittleness of steel goes up. Normal mild steel has yield strength of 230 MPa, while high strength steels with yield strength up to 480 to 500 MPa are commonly used in some applications. High strength steel for tower applications is normaly limited to steels with yield strength upto 350 Mpa.
If the steel used is normal mild structural steel, which has not been heat treated to achieve any increased strength then galvanizing does not affect the properties in any way. If steel used is work hardened, then hot dip galvanizing (dipping in temperature upto 415deg C will certainly have some annealing effect on steel, which may reduce the strength of steel.
In a situation, where it is not possible to measure the various parameters which affect the quality of material, country of origin of material may be considered to be a reasonable assurance of quality. Today, when all parameters, which have effect on quality, can be quantitatively measured.
End use of steel determines the properties required from raw material used. If the end use of steel is to cut another piece of steel on a lathe machine then it is important the steel is must maintain its strength even when it is red hot. All properties are not important for any end one use. When end use of steel is tower manufacture, then the following properties should be evaluated.
These terms stand for standards of various countries. For example BS stands for British Standard, IS stands for Indian Standard, ISO stand for International Standards Organization, ASTM is an American Society of Testing Materials etc.
Each country has different types and grades of materials and technology available within the country. Each country makes its standards to make best use of
As the scene changes or new technology becomes available, the standards also are modified or deleted and new standards are introduced to suit the new environment of the country.
The tower design process consists of the following steps.
Yes. Each standard of any country normally describes several grades of steel. If end use of steel is tower manufacture, only structural properties need to be compared. It is always possible to find equivalent steel for the grades normally used for tower manufacture.
Some of the standards are available.
For reasons of economy, all the loads are not considered to be acting simultaneously.
For example – When there is earthquake, then wind load is not considered and vice-versa.
Normally wind load + ice load (Whenever it is present) is the controlling load.
Fabrication is an important factor of design for the quality of tower. If fabrication of tower is not proper than structural capacity of tower may be reduced. Following situations explain.
Designer provides size of each member. He also provides number of bolts and diameter of bolts at each joint. After that it is responsibility of detailer to make production drawing without sacrificing the strength of tower.
Tower is a steel structure. If members have corroded then obviously the available strength will be reduced to that extent. Looseness of nut bolts also affects the strength of a joint. Hence it is mandatory that maintenance of tower should be done as recommended by the manufacturer.
Strength of a joint is determined not only by the strength of bolts but by the number of the bolts also. Whenever a joint is designed with high tensile bolts, designer will reduce the quantity of bolts per joint because lesser quantity of high tensile bolts will provide the required strength in the joint. AKME GLOBAL always prefer to use 8.8 Grade bolt, which has the high tensile properties.
Following inputs are required from user.
The tower should have enough reserve strength to accept additional load due to proposed antenna addition. Weight of antenna is really not of many consequences. But what is important, the sideways forces on the tower due to wind area of antenna, shape of antenna and the height at which the antenna will be mounted. AKME GLOBAL can assist you in evaluating available spare structural capacity or the possibilities of strengthening your tower for additional antennas.
Following inputs are required from user.
The tower should have enough reserve strength to accept additional load due to proposed antenna addition. Weight of antenna is really not of many consequences. But what is important, the sideways forces on the tower due to wind area of antenna, shape of antenna and the height at which the antenna will be mounted. AKME GLOBAL can assist you in evaluating available spare structural capacity or the possibilities of strengthening your tower for additional antennas.
Whenever high tensile bolts are used in tower joints, it becomes necessary to tighten the bolts to predetermined tightness, because then only required strength of joint is achieved.
Earthing and Grounding an object/tower means providing an electrical connection between that object/tower and mother earth. This electric connection is achieved by running an electrical wire/strip between the tower and an earth electrode. Earth electrode is a metal plate/ pipe/sphere properly embedded at a depth in the earth. This Grounding of tower is necessary to prevent damages to delicate instruments or humans due to voltage/currents and for better performance of the communication system.
Lightening arrestor is a conductive metal device mounted at the highest point on the tower. Tall objects like microwave tower are prone to damage by lightning strikes. To prevent the tower from lightening strike, a lightening arrestor is fitted on the top of the tower. This lightening arrestor is connected to earthing.
Tower materials are normally hot dip galvanized to prevent them from rusting. Applying paint provides an additional layer of protection. AKME GLOBAL recommends that painting should be done in all cases. The paint should be renewed, whenever signs of rusting are observed during periodic inspection.
There are various situations where the paint should be done before erection or after it.