An NDE instrument based on the longitudinal stress wave concept and developed through an EPRI project [2], was used to strength grade approximately two hundred new and thirty old distribution and transmission size western red cedar poles. Some of these old poles were removed from the ground after 40 years of service. Effectiveness of the longitudinal stress wave instrument for strength grading of poles was verified by comparing the NDE data with the results obtained from breaking of thirty poles.

The above instrument and a second NDE instrument, based on the longitudinal ultrasonic velocity principle, were also used to evaluate the effect of Chromate Copper Arsenate (CCA) preservative treatment on the mechanical properties of thirty western red cedar poles. Prior to the preservative treatment, load carrying capacity and longitudinal ultrasonic speed for each of these poles were measured using these two instruments. Also, stiffness of each of these poles was measured from full-scale deflection test. All these measurements were repeated after the treatment. Change in strength and stiffness due to the treatment was quantified for each of these poles. Some of the poles, identified as weaker polies, were broken for verification of the NDE measurements. The proposed paper will summarize the results obtained from this research program.

REFERENCES

1. G. Bhuyan and D. Chetwynd, Strength and Stiffness of New Wood Utility Polies", Canadian Electrical Association Project, CEA 119 D 1010 report, June 1994
2. R. W. Anthony et al, Longitudinal Nondestructive Evaluation of New Utility Wood Poles", EPRI TR-100864, Vol. 1, Project 3078-01, 1992