This code of practice provides guidelines for the geotechnical and structural design of foundations for self-supporting communication towers, including radar, microwave, and TV towers. It covers site investigation, load calculations, design criteria for stability against overturning and uplift, and specifies requirements for various foundation types like isolated footings, rafts, and piles.
Code of practice for design and construction of radar antenna, microwave and TV tower foundations
Quick Reference Values
Factor of Safety against Overturning (Normal Loads)2.0
Factor of Safety against Sliding (Normal Loads)1.5
Factor of Safety against Uplift (Weight of footing + soil)1.5
Factor of Safety against Bearing Capacity (Normal Loads)2.5
Permissible Total Settlement (Raft Foundation)75 mm
Permissible Angular Distortion (Tilt)1/500
Key Formulas
Stability Check (Overturning): Restoring Moment / Overturning Moment ≥ 2.0
Uplift Resistance Check: (Weight of Foundation + Weight of Soil Cone) / Uplift Force ≥ 1.5
Practical Notes
This code is dated (1985). Always use the latest versions of IS 875 (Part 3) for wind loads and IS 1893 (Part 4) for seismic loads on telecommunication towers.
Uplift resistance is frequently the governing design factor for tower foundations, especially for isolated footings under high wind conditions.
The weight of the inverted frustum of soil above the footing is critical for calculating uplift resistance. Ensure proper compaction and consider the soil's submerged unit weight if the water table is high.