DESIGN - Prestressed Concrete Transmission Pole Structures - page 32

Fig. 4-1. Spun prestressed concrete pole cross section
Source: Illustration courtesy of Valmont Newmark. Reproduced with
permission.
eccentric loading of the pole's center of gravity coupled with the weight
of the conductors, insulators, and other applied vertical loads. These sec-
ondary moments must be accounted for in the design of a structure.
It is important to consider the effects of material and geometric non-
linearity in the structural analysis, not only because of the secondary
moments induced but also to reasonably predict structure defl ections for
insulator, conductor, and other electrical clearance calculations.
Prestressed concrete pole designs are best accomplished by suitable
nonlinear analytical methods that account for the prestressed concrete
material and section behaviors previously described.
DESIGN CONSIDERATIONS
Concrete poles and structures designed to meet the same loading and
functional requirements may differ signifi cantly in cross-section dimen-
sions and reinforcements because of varying manufacturing capability of
the suppliers, quality and regional variability of the raw materials used,
the design philosophy of the engineer, and the analytical design method-
ology used (including recognition that both linear and nonlinear material
behaviors can be present within the same analysis). The development of
a prestressed concrete pole design requires many considerations includ-
ing limitations of pole length, diameter, and taper (functions of casting
mold variation and availability from producing suppliers).
Loading Considerations
The required structure strength and behavior requirements are typically
defi ned by the Purchaser and should include the following information: