The design considerations of prestressed concrete poles
The pre stressed concrete pole for power transmission line are generally designed as member with uniform prestress since they are subjected to bending moment of equal magnitude in opposite directions. The poles are generally designed for following critical load conditions,
1. Bending due to wind load on the cable and on the exposed face.
2. Combined bending and torsion due to eccentric snapping of wire.
3. Maximum torsion due to skew snapping of wires.
4. Bending due to failure of all the wires on one side of the pole.
5. Handling and erection stresses.
(b) What are the advantages of partially prestressed concrete poles?
· Resistance to corrosion in humid and temperature climate and to erosion in desert areas.
· Freeze thaw resistance in cold region.
· Easy handling due to less weight than other poles
· Fire resisting, particularly grassing and pushing fire near ground line.
· Easily installed in drilled holes in ground with or without concrete fill.
· Lighter because of reduced cross section when compared with reinforced concrete poles.
· Clean and neat in appearance and requiring negligible maintenance for a number of years, thus ideal suited for urban installation.