Development of an alternative method and design for setting wood utility poles on rock

Abstract

Manitoba Hydro’s current practice for setting wood poles onto exposed rock has been generating safety concerns for years. This method entails fusing rebar into holes drilled in the rock with molten sulphur. Unfortunately, accidental overheating of sulphur causes it to lose its strength properties and has lead to numerous premature failures. Full-scale testing by Manitoba Hydro has also revealed that these grouted anchor rods performed poorly in bending at the ground-line while the poles remained in good condition.

A research program was conducted at the University of Manitoba’s McQuade Structural Laboratory that focused on developing a prefabricated steel base mount detail. Nine tests were conducted using Lodgepole Pine specimens in the mount with mechanical fasteners, crushed limestone, or sand as the annulus material. The experimental results showed the mount, with either crushed limestone or sand, successfully developed the full moment capacity of the wood pole and satisfied limits on deflection.