**General Order 95**

**Appendix F**

**Typical Problems**

**Part III
**

To maintain poles in proper position at angles and corners,
it is generally necessary to use guys or some other form of pole bracing.
Unless the line is dead–ended, the pull of the conductors is taken as being
the same throughout the line.

The degree of unbalanced pull at an angle or corner pole is dependent upon
the angle in the line at that point; that is, the greater the angle in the
line, the greater is the magnitude of unbalance.
Rule 47.3
specifies that when the longitudinal loads in a structure are not normally
balanced, the members stressed shall be of such strength as to withstand the
total unbalanced load with factors of safety equal to those of
Table 4
. As it is assumed that the line considered in this problem is Grade “A”
construction, the pole would be required to provide a safety factor of 4 against
unbalanced loads; where guys are used to take the unbalanced loads they must
provide a safety factor of 2.

It is assumed that the line discussed in the foregoing deadend problem crosses
from one side of a street to the opposite side, that the longitudinal distance
along the street between the two poles concerned is 77 feet, and that the
angle of deviation is 33° (see sketch). This would result in an unbalanced
force being exerted in the direction of A of

Assuming the pole height and framing as shown in
Part 2
, the top circumference of pole to be 25”, the ground circumference to be
50” and the center of load to be 37.4 feet above ground line (as determined
in Part 2
), the fiber stress on the pole at the ground line is as follows:

Bending moment, M = 37.4 x 10,550 = 394,400 pound–feet

where circumference = 50” and d = 15.9”

As a safety factor of 4 is required, the allowable working stress is
or 1,400 lbs per square inch, and therefore the use of guys is necessary.

A single guy attached at the center of load could be used provided the modulus
of rupture with a safety factor of 4 is not exceeded. The stress due to guying
at this point is as follows:

Bending moments

Total moment=463600 pound-inches

Section modulus, E

The section modulus (E) at 37.4 feet above ground is 89.6 inches cubed,
which is the value computed in
Problem 2

Fiber stress:

The fiber stress is

Since this stress exceeds the allowable stress of 1,400 lbs per sq. in.
for the pole, it is necessary to place guys at more than one point on the
pole, and therefore, they are attached at positions similar to the guys shown
in the diagram on
Page F–22
.