requirements of tower/antennas

7/23/2019 Requirements of Tower/Antennas

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6. TOWERS

6.1 Introduction

This chapter describes the requirements of antenna supporting structures for the

GSM network. The bidder shall offer the antenna supporting structures as describedin this chapter.

6.2 Bidders Experience

The bidder shall offer such structures from manufacturer(s) who have adequateexperience in manufacture and supply of towers used in telecommunicationnetworks, preferably cellular mobile network.

The bidder shall provide the details of the supplies the manufacturer of such antennasupporting structures have made and shall include relevant certificates fromorganizations to which such supplies have been made.

6.3 Work Required Under the Specification

The work required under this specification covers:

i) The supply, delivery and construction of foundation and rooftop 5m/8mtripod, 3-legged angular 20m SS steel tower structure and ground based18m pole, including ancillary items like lightening rod, earthing system,foundation bolts and RF cable support. The tower structure shall be providedwith appropriate and adequate facility for mounting and supporting GSM andmicrowave antennas.

ii) Design of towers and tower foundations.

Type of structure required at the different sites is given in Table-1. Thestructure shall be designed taking into consideration the type and number ofantennas to be mounted as mentioned in the Table-1 with design parametersspecified below.

6.4 Loading

The wind loading on tower structures and antennas shall be based on a ground levelwind velocity of 160 km/hr. and increasing with height in accordance with British

Standard BSI CP3: Chapter V: Part 2: September 1972.


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6.5 Design Parameters

Description roof top tripod/tower Ground basedtower/pole

a)Wind velocity[km/hr] 160 160

b)Bearing capacity

of the soil. [Mt/m.sq.] - 7

c)Design safety factor 2 2

Description of Antenna Structures

Type of Antenna Structure Type and number of antennas to beSupported

Ground Structure 3 legged lattic

Structure, height 20 m.

6 Sectoral Antennas each approx. 3ft ta

4" diameter and 10 Kg weight. 2 solidparabolic antenna of diameter 1.2m

Roof top 5m tripod 3 Sectoral Antennas each approx. 3ft ta4" diameter and 10 Kg weight and 2 solparabolic antenna of diameter 0.3 to 0.6

6.6 Description of Items

6.6.1 The structures shall be used for mounting antennas as mentioned above. Thebidder shall take into consideration in their design and offer to include the followingitems for each tower.

a) Foundation bolts

b) Lightning arrestors and earthing system including installation accessories

c) Antenna fixing arrangement to fix it to the tower at required height

d) Simple ladder for roof top tower and internal caged ladder and internal

platforms for SS towers

e) Facility to run RF cable vertically along side of the ladder

f) Horizontal RF cable runway between tower and equipment room

6.6.2 The height of ground structure shall be 20m SS tower and 18m Pole and thatof rooftop shall be 5m/8m tripod. The complete tower (legs, web members, basestubs etc.) shall be supplied in knocked down condition, to be assembled on site bymeans of bolts and nuts.

6.6.3 Climbing ladder shall be provided together with the safety cage inside the


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tower. RF cables will run along the climbing ladder fastened to it by means ofsupports bolted with a spacing of not more than 1m.

6.7 Type of Structure

6.7.1 General

a) The type of the structure offered along with ancillary items shall beillustrated diagrammatically.

b) All structural members except required specifically to provide, shall be madeof angles. The members/ sections shall be assembled at the time of erectionby means of jointing plates, bolts and nuts. No welding of any kind shall beallowed at the sites.

c) The offer shall include all parts required for complete erection of thestructure. Nut-bolt, washer and similar minor items shall be provided inexcess by 10% of the actual quantity required or minimum one extra for

small number, whichever is more for each type.

d) All members of the structure shall be straight unless required to becurvilinear form, and shall be free from twist and kinks.

6.7.2 Platforms and railings

i) Two (2) internal platforms are to be provided for 20m towers. The exactheights at which these platforms shall be built depend on the height of GSMantenna and hence shall be decided later.

ii) Area of platform shall not be less than 2 Sq.m. Free passage shall beprovided through the appropriate edge of every platform to run the RFcables.

iii) Loading capacity of the platforms shall be more than 200kg/sqm.iv) Platform docking shall be made of expanded metal or similar material

adequately supported on steel members of appropriate size.v) Platforms shall be provided with handrails at a height of 1.0 meter above the

decking, intermediate rails at approx. 0.5 meter above the decking and kick-rails at decking level.

vi) Handrails shall be provided on all platforms and shall be continuous aroundthe outside perimeters of the platform, as far as consistent to the access tothe guard so that free access to the ladder may be gained from the platform.

Handrails shall not be structural members and shall be removable tofacilitate the mounting and maintenance of the antennas.

6.7.3 Lighting protection and earthing

Lightening discharge rod of approx. 2-meter length and 16 mm diameter, along withfixing materials, shall be provided. The stranded copper wire and having 8 mmdiameter shall be supplied as required to be clamped to the lightning rod at one endand grounding rod at the other end. The grounding rod shall be made of hard


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copper/ brass and shall be 2.5m long and 16mm diameter. Suitable number ofgrounding rod and clamps shall be provided to ground the legs of the tower.

For the poles, lightening discharge rod of approx. 1 m length shall be used withsimilar accessories as described above.

6.7.4 RF cable support facility

Facility to run at least 6 RF cable of one inch diameter shall be provided for eachtower. A 5-meter long horizontal bridge (in two sections each of 2.5m long) withthree vertical supports shall be provided for each tower.

6.7.5 Ladder

a) Internal caged ladder, starting from base to the top platform, shall beprovided for each tower.

b) Loading capacity of the steps shall not be less than 120kg.c) Width shall not be less than 40cm.d) Rise of ladder steps not more than 30cm.e) Convenient and free access to and from the ladder shall be provided at

every platform level.

6.7.6 Foundation bolts

Foundation bolts/anchor bolts shall be provided for each tower supplied.

6.7.7 Template

Two sets of template for setting the foundation bolt for each type of antennamounting structure shall be provided.

6.7.8 Antenna mounting pipe

Antenna fixing arrangement shall be provided for each antenna. Required number ofantenna mounting pipes, depending on the type of antenna offered, shall beprovided. Fixing shall be possible on all sides and/or corner of the top section ofeach tower. Hence, in order to avoid any local twist or deformation of the towermember special attention shall be taken by the bidder to provide extra thickness ofthe structural member, where such pipes shall be mounted.


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6.7.9 Design Calculations

The bidder shall submit detailed structural calculations for

a) 20m high light self supported tower,b) 5m/8m tripod

c) 18m pole

Bidders are required to provide foundation design analysis for offered structures.The bidders shall provide in their offer an estimated weight of steel and volume ofconcrete required as relevant.

The bidder shall submit drawings and design data for the foundation of thestructures he is proposing to supply bearing in mind the stability of the completedstructures with the antenna(s) mounted.

6.7.10 Steel work

The steel used in fabrication of towers shall comply with IS 2830-1975, Grade 410-Sp2 or equivalent standards for steel metal used in the fabrication of structures.

6.7.11 Deflection and Distortion

a) The tower shall be designed to withstand, without any permanent distortion,loads due to the wind acting on the antennas and the tower.

b) The erected structure under the condition of negligible wind shall not deviate

from the vertical position by more than 1/8% of the height of the structures.

c) Each structure shall be designed such that sway of the structure from thevertical shall not exceed 1% of the height under full wind load.

d) Tilt and twist of the structures shall not exceed three degrees at full wind load.The bidder shall supply with his bid documents the design information of themaximum deflection, tilt and twist at the top of the structure when subjected tothe maximum design wind velocity.

6.7.12 Galvanizing

a) All steel work and fittings used in the assembly of towers except those usedin concrete foundation, shall be galvanized by the hot dip process afterfabrication.

b) If , for manufacturing reasons, the bidder proposes a treatment other thanhot dip galvanizing for certain parts of the tower , he shall state specificallythe fittings to be so treated and process to be used


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c) The thickness of galvanization shall be more than 500 grams per square

meter.

d) Steelworks forming portion of the foundation shall be galvanized down to adepth of not less than thirty [30] cm under the surfaces of the concrete.

e) Painting or cadmium plating shall not be used in any instance as a sole ofmeans protection against corrosion except for repair purposes.

6.7.13 Marking

All structural members are to be punch marked sequentially beforegalvanizing in order to identify every member during erection. Suchmarking information shall be provided in the diagrams to be provided.

6.7.14 Documentation

Two sets of complete documentation for each type of structures shall beprovided. It shall cover the following:-

a) Installation of each structure and other ancillary items.b) Structural analysis.c) Foundation design where applicable.

6.7.15 Tower Lights and Painting

All towers shall be supplied with relevant international aviation painting and towerlight systems. Painting of towers shall be done after galvanizing. Final one coat ofpainting shall be done after tower erection.


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BILL OF QUANTITY (Towers)

Item Description Bhairahawa Pokhara Nepalgunj DhangadiTotal

Quantity

PhasePhase

I

Phase

II

Phase

I

Phase

II

Phase

I

Phase

II

Phase

I II

NETWORK II

1

Self Support Tower

(SS Tower)

1.1

Roof Top 5m/8m

Tripod

1.1.1 Tower Material 97 38 81 20 82 35 63 28 444

1.1.2 Tower Foundation 97 38 81 20 82 35 63 28 444

1.2 20m SS Tower

1.2.1 Tower Material 29 19 49 33 52 34 37 25 2781.2.2 Tower Foundation 29 19 49 33 52 34 37 25 278

1.3

18m Ground Based

Pole

1.3.1 Pole Material 20 15 47 33 44 31 27 18 235

1.3.2 Pole Foundation 20 15 47 33 44 31 27 18 235

2 Transportation

2.1No of accessible site

by vehicle 102 50 124 60 125 70 89 50 670

2.2

No of Site not

accessible by vehicle 44 22 53 26 53 30 38 21 287

3 Services

Installation,

Supervision,Testing,

Commissioning,

Optimization,

Warranty Services-

Lot

3.1

Tower installation-

Lot

Roof Top 5m/8m

Tripod 97 38 81 20 82 35 63 28 444

20m SS Tower 29 19 49 33 52 34 37 25 27818m Ground Based

Pole 20 15 47 33 44 31 27 18 235

3.2 Tower Grounding 146 72 177 86 178 100 127 71 957


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NETWORK III

Item Description Biratnagar Bhadrapur Rajbiraj

Total

Quan

tity

Phase

I

Phase

II

Phase

I

Phase

II

Phase

I

Phase

II

1

Self Support Tower

(SS Tower)

1.1Roof Top 5m/8m

Tripod

1.1.1 Tower Material 102 38 51 17 80 33 321

1.1.2 Tower Foundation 102 38 51 17 80 33 321

1.2 20m SS Tower

1.2.1 Tower Material 32 21 21 14 30 20 138

1.2.2 Tower Foundation 32 21 21 14 30 20 138

1.318m Ground Based

Pole

1.3.1 Pole Material 23 17 20 15 18 12 1051.3.2 Pole Foundation 23 17 20 15 18 12 105

2 Transportation

2.1Site accessible by

vehicle 110 53 64 32 90 46 395

2.2

Site not accessible

by vehicle 47 23 28 14 38 20 169

3 Services

Installation,

Supervision,

Testing,

Commissioning,

Optimization,

Warranty Services-

Lot

3.1

Tower installation-

Lot

Roof Top 5m/8m

Tripod 102 38 51 17 80 33 321

20m SS Tower 32 21 21 14 30 20 138

18m Ground Based

Pole 23 17 20 15 18 12 105

3.2 Tower Grounding 157 76 92 46 128 65 564

requirements of tower/antennas

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