The aim of the project is to Design, supply, 120m high self-supporting four legged steel lattice communication tower including inner ladders, cable trays, inner &outer platforms, galvanizing, obstruction painting & obstruction lightning and accessories for mounting/installation UHF, HF, FM, Dish antenna etc, and their feeder cable as per the general requirement
2.2.Tower shall be four legged angle iron /tube type.
The American “Structural Standard for Steel Antenna
Towers and Antenna Supporting Structure” RS222C or
The British Codes of Practice 3 Chapter V Part 2, 1972.
BS8100 is also acceptable
Shall be metal-arc welding complying with BS 1856 for
mild steel and BS 2642 for manganese steel whichever
Comply to BS449 or AISC
Comply with either BS729 or ASTM/A123 or equal in
other standard and codes and minimum 660g/m2 Zn
coating shall be provided.
Mild Steel angles and plates
BS EN 10025 1993 Grade 275 or JIS G3101 SS400
High Tensile angles and plates
BS EN 10025 1993 Grade 355 or JIS G3101 SS540
BS 4449: 1978, Yield stress fy = 250MPA(Mild steel)
fy = 400MPA (Hot rolled high yield)
BS 3692 Grade 8.8 (Other grades shall not be
acceptable). Minimum bolt diameter shall be 16 mm
6. Wind Loading and Tolerances
6.1. Operational 140km/hr. & survival wind speed of 160km/hr. (All 3 Sec Gust)
6.2. Twist and swing should not exceed 1.0° under extreme wind condition as specified in clause 6.1 above.
6.3. The tower-loading figure should accommodate following equipment
6.4. A safety factor of 1.7 should be used and material partial safety factor should be 1.1
6.5. The erected tower, under the condition of negligible wind, shall not deviate from the vertical position by more than one eight percent (1/8 %) of its height, and shall be straight within 2.5cm of the nominal geometric position; the erected tower shall be free of inherent twists.
7.1. Galvanizing process should comply with either BS729 or ASTM/A123 or equal in other standard and codes (please quote if others).
7.2. All steelwork and fitting used in the assembly of the tower including the platforms, climbing ladder, cable ladders, holding down bolts shall be galvanized by the hot dip process after fabrication and before any assembly.
7.3. If, for manufacturing reasons, Tower Supplier proposes to use a treatment other than galvanizing for certain parts of the tower, then the Tower Supplier shall state specifically the fittings to be so treated and process to be used. Thickness of galvanization shall be more than 610 g/m2.
7.4. Steelwork forming portion of the foundation shall be galvanized down to a distance of not less than Thirty (30) cm under the surface of the concrete. This steelwork may be completely galvanized provided that the design of the foundation does not rely on a bond between the concrete and the encased steelwork.
7.5. Painting or cadmium plating shall not be used in any instance as a sole means of protection against corrosion.
7.6. Tower Supplier needs to provide detailed document regarding the galvanizing plan and that shall include all contact details, Capacity and quality control system, etc.
7.7. Samples of galvanizing selected at random may be required to test by the Tower Supplier in the presence of the “*****”.