Page 106 - McWane Poles Sales Manual 2024

106
McWane Poles, A Division of McWane Inc.
TECHNICAL NOTES
Sample Calculated MOM Design MOM Ratio
1 131.3 125 1.050
2 77 78 0/987
100 34 23 1.478
database will include 100 material samples. Material data samples collected need to represent pole
production, therefore the selection of samples needs to be proportional to the number and types of poles
and pole sections sold. From the 100 samples, wall thickness, diameter, yield strength, distance from
pole tip of diameter measurement, and pole class and length should be recorded. Samples should be
taken from poles or sections after all quality inspections are performed so the samples represent poles
that would actually be shipped to customers. Material samples for sections 3-8 can be obtained from the
portion of sections that are scrapped when poles are cut to length. Sections 1 and 2 can be collected from
unused sections or from poles that have been rejected for non-structural reasons.
Ratio of Calculated to Design Moment Values
A table will be generated with 100 ratios of Calculated Moments to Design Moments. The Calculated
Moments will be derived by plugging the observed material properties (thickness, diameter, and yield
strength) of a given sample into the Bending Moment Capacity formula above. The following is an example
of a Calculated Moment capacity at a given cross-section:
Thickness: .29 inches
Diameter: 13.26 inches
Yield Strength = 42,000 psi
I = (3.1416/64) x ((13.26 inches)^4 – (12.68 inches)^4) = 248.66 inches^4
S = 248.66 inches^4 / 6.63 inches = 37.50 inches^3
MOM = S x FY
MOM = 37.50 inches^3 x 42,000 psi = 1,575,092 inch-pounds
MOM = 1,575,092 inch-pounds x 1 foot / 12 inches = 131,257 foot-pounds and 131.3 foot-kips
The Design Moment will be the moment based on the PLS Pole design model’s material properties for the
same pole with a cross sections that is the same distance from the tip as the sampled pole.
The resulting 100 ratios will be used to calculate the mean, standard deviation, coefficient of variability,
and ultimately the 5% LEL and nominal strength as a ratio of the PLS Pole design strength. After the initial
sampling and calculation of nominal strength, ongoing sampling should be conducted to increase the
database and increase confidence in the estimated nominal pole strength.
Section Sampling Plan
Sections to be sampled will be a representation of sections and poles shipped in the previous 12 months.