For many anchor rods, steel is not easily welded. Therefore, mechanical threading connections (e.g. coupling nuts) are generally chosen. However, a new threaded rod extension field welded to the existing anchor rod is also possible using butt welding. Butt welding two round rods together requires special detailing, as shown in Figure 5.
Many repair measures can be determined according to individual situations, but it is better to prevent corrosion of anchor bolts in advance.
Maintenance
Lighting poles are designed to be safely exposed to aggressive Canadian weather for several decades. It is important to emphasize some issues in the ongoing landscaping and property maintenance of areas surrounding concrete poles.
Not raising the grade around the footings
It is important to emphasize the finished grade around concrete footings should not be raised by adding top soil.
Shown in Figure 6, whole anchor bolts and aluminum collars are buried in earth. Water and moisture will remain regardless of measures taken. It is recommended earth around the footing be re-graded so the top can be above the newly finished grade by at least 50 mm (2 in.).
Cutting branches around lighting poles
Sometimes, the upper part of a lighting pole can be completely immersed in branches of a nearby tree. The branches can touch the pole and produce unexpected forces in severe weather conditions. It is recommended the branches be cut off and kept at a 1-m (3.2-ft) clearance.
Conclusion
Lighting poles are common items in our daily life, so little attention is paid to them. After a long time of being ignored, however, they will become a problem. With proper attention to design, construction, and maintenance, concrete lighting poles can have a long and problem-free service life.
Bill Yao, P.Eng., has been a civil/structural designer for 20 years. He currently works as a structural engineer at an engineering firm in Markham, Ont. He can be reached via e-mail at wyao03@yahoo.com.
