Towers Monopole




 This specification document covers the projecting principles of monopole towers that will be used antenna   installations    in   the   GSM base    station    installation    projects 

In case there are conflicts between various standards and codes or engineering design data, the most rigid standard and code will be taken as a basis after seeking the approval 

In case the revisions of the related standards will be published, following the new standards and renewing the production according to these standards is the contractor’s responsibility after seeking the approval

Metrical system will be used in the measurements.




 3.  DESIGN PRICIPLES

Towers will be designed according to the following heights unless otherwise requested by Client.


 Towers will be designed according to the following heights unless otherwise requested by client.

The monopole could be polygonal slip joint or flanged type manufactured · 

All monopoles shall be complete with the accessories for antenna installation, cables fixing, access  ladder  up to the top of the structure  along with a safety  rail & safety  hanger, grounding, lightning conductor system & aircraft warning light system ·   

The contractor  shall design  calculations,  outline  drawings,fabrication and assembly drawings, fabrication charts, and bill of materials prior to delivery.

Design must be done to allow operations and maintenance works to be performed easily.

Dimensioning of the construction and connection elements will be done in accordance with the latest issue of Guide for Design of Steel Transmission  Towers-ASCE  published by American Society of Civil Engineers – ASCE.

A climbing ladder will be built on the monopole in order to provide the maintenance  and operations personnel to climb on the tower. Ladder step spacings will be maximum 30 cm. A safety rail & fall arrestor shall be provided attached to the access ladder.

Tower  will be designed  to allow the installation  of aircraft  warning light and  a copper lightning arrestor at the highest point with a minimum length of 1.2 meters.  Easy access to the aircraft warning lamp shall be available.

The contractor is responsible  to obtain results from tower designs, acceptance tests & quality assurance,   such   that   compliance   with   all conditions   prescribed   in  these specifications is evidenced. 

The contractor  is not allowed to use the designed monopoles for any other application without the prior consent of Client.

Each monopole shall be designed to be at optimum dodecagonal horizontal cross section (as swaying and vibration should be held at minimum) and self supportive and be calculated as per tensile-compressive forces system.

Life time of the monopoles shall be minimum 30 years.



 


 5.  PLATFORMS

 Monopoles can be supplied with or without top platform according to the request and/or approval of Oman Mobile.
· The top platform shall have 3,0 m diameter, for the monopole without a top platform a small light circular area shall be provided for access to the antennas.
· Platform shall  be furnished with non-slip floor appropriately  fixed with a suitable bearing structure with bolted joints. Moreover the platform floor shall not allow tools, and objects to fall.
· Top platform shall be provided with foot stop plate (h=15cm) and protective railings (made with two currents) not less than 110 cm in height, in accordance with regulations in force on the subject.
·   Working Platform shall be accessed via a hatch complete with opening and closing system.

It shall be possible for hatches to remain open if necessary.

All the underground connections  of the earthing  system  shall be made with Cadweld method.

 

7.  STEEL ELEMENTS

If the   connection   elements are  designed   with  flanges, number  of  attachments  and eccentricity of the attachments will be kept in minimum as much as possible.
· Dimensioning of the elements and connection elements will be done in accordance with the latest issue of Guide for Design of Steel Transmission Towers-ASCE published by American Society of Civil Engineers – ASCE.
· The necessary holes needed for the ground connection must be designed.

· Monopole Connection  and Fixation:  The monopole base  plate  will be attached  on the concrete  base via achorage  bolts and proper grouting shall be applied 
· Contractor shall make his own survey to the sites if required and shall be responsible for obtaining all dimensions and level necessary for the proper fabrication of the steelworks.
· The Contractor shall be responsible for every piece being made to the correct form and size.

· The Contractor shall inform the Engineer of the date on which fabrication will commence, shall  keep  the Engineer  informed  of the fabrication programme  and  shall  permit  the Engineer  or his representative full access to his factory at all reasonable  hours for the purpose of inspecting the steelwork at any stage of its manufacture.  Contractor must clearly understand that any material and workmanship not complying with this specification shall upon inspection  whether  at his works,  the site or in erected  position  be  rejected  and replaced to the entire satisfaction of the Engineer.

8.  MONOPOLE LOAD ASSUMPTIONS

The following loads have to be considered for the monopole design: Antenna Load:
·   N°6 mobile antennas with weight of 15 Kg each and dimensions of 2.58 x 0.3 x 0.15 m.

·   N° 2 solid parabolic antennas with average weight of 25 Kg and diameter of 0,6 m.

·   N° 2 solid parabolic antennas with average weight of 45 Kg and diameter of 1,2 m.

Other Loads
Dead load for auxiliary equipment such as feeder, feeder joints, antenna structure and other installation equipments.

Wind Speed:

·  Design wind speed shall be 160 Km/h (45 m/s).

· Operational wind speed (maximum twist and tilt shall be ±0.5 degree at this speed) shall be 120 Km/h (34 m/s).

10. CABLE LADDERS & SUPPORTS

Vertical Cable Ladders

The vertical cable ladder could be either external supports running next to the access ladder on the monopole or could be internal J-Hooks for hanging the cables inside the
monopole.


11. ACCESS LADDER & FALL ARREST SYSTEM

The Monopoles  are to be equipped  with hot dip galvanized  climbing  ladders  with approved safety system. Safety system shall consist of a fall arrestor (mouse) that can freely move on a steel cable or a perfectly continuous rail and in case of fall it will lock itself protect the individual from falling down. The width of the climbing ladder shall be at least 400 mm. The spacing of the step rungs (thickness minimum 16 mm) shall be 250 mm maximum and they shall be capable to carry 1 kN concentrated load (gM   = 1.5). There shall be no obstruction behind the climbing ladder for the foot.

 12. FASTENERS

Bolts, nuts and washers

The connection bolts, nuts and washers will be according to any of the following standards   (or equivalent):
     

Dimensional standards for fasteners





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