The purpose of this study is to account for failures of wood utility poles in wind storms based on dynamic analysis and pole imperfections. The utility pole supporting multiple overhead transmission lines is modeled as a uniform Bernoulli–Euler cantilevered beam fixed at the base and subjected to three types of suddenly applied transverse loads that simulate a wind gust: a uniform pole pressure, a point load at the tip accounting for line and transformer drag, and another point load near midlength, accounting for drag on lines strung from that location. The dynamic pole moments are based on normal mode calculations rather than static calculations with a dynamic impact factor, and the critical flexural stresses include stress concentrations arising from pole imperfections such as holes, knots, and surface gouges. A case study illustrates the results for one of about 400 failed wood poles downed in a single New Jersey storm in 2003 with 107 km/h (67 m/h) wind gusts. Here, the critical pole stress based on the dynamic model and a hole imperfection exceeded the proportional limit stress of the wood. The predicted dynamic stresses are higher than those based on the National Electrical Safety Code.

1.
Pellicane
,
P. J.
, and
Franco
,
N.
, 1994, “
Modeling Wood Pole Failure
,”
Wood Sci. Technol.
0043-7719,
28
, pp.
261
274
.
2.
Elkins
,
L.
,
Morrell
,
J. J.
, and
Leichti
,
R. J.
, 2007, “
Establishing a Through-Boring Pattern for Utility Poles
,”
Wood Fiber Sci.
0735-6161,
39
(
4
), pp.
639
650
.
3.
American National Standards Institute (ANSI)
, 2002,
American National Standard for Wood Poles
,
ANSI
,
New York, NY
, pp.
1
26
.
4.
USDA
, 1954,
Wood Handbook 72
,
Forest Products Laboratory, USDA
,
Washington, DC
.
5.
Koch
,
P.
, 1985,
Agricultural Handbook 605
,
USDA
,
Washington, DC
.
6.
Wolfe
,
R. W.
,
Bodig
,
J.
, and
Lebow
,
P. K.
, 2001, “
Derivation of Nominal Strength for Wood Utility Poles
,” Forest Service, USDA, Technical Report No. FPL-GTR-128.
7.
Pilkey
,
W. D.
, and
Pilkey
,
D. F.
, 2008,
Peterson’s Stress Concentration Factors
, 3rd ed.,
Wiley
,
Hoboken, NJ
.
8.
IEEE
, 1993,
National Electrical Safety Code
,
IEEE
,
New York
, pp.
143
153
.
10.
Wilson
,
J. F.
, 2003,
Dynamics of Offshore Structures
, 2nd ed.,
Wiley
,
Hoboken, NJ
.
11.
Clough
,
R. W.
, and
Penzien
,
J.
, 1993,
Dynamics of Structures
, 2nd ed.,
McGraw-Hill
,
New York
.
12.
Timoshenko
,
S. P.
, and
Gere
,
J. M.
, 1961,
Theory of Elastic Stability
, 2nd ed.,
McGraw-Hill
,
New York
.
13.
Wolfram
,
S.
, 1999, MATHEMATICA Version 4, Wolfram Media, Champaign, IL.
14.
Gaythwaite
,
J.
, 1981,
The Marine Environment and Structural Design
,
Van Nostrand Reinhold
,
New York
.
15.
Wilson
,
J. F.
, 2004, “
Segmented Impact Fracture of Toppling Truncated Cones and Tall Trees
,”
Int. J. Impact Eng.
0734-743X,
30
, pp.
351
365
.
You do not currently have access to this content.