STRUCTURAL CONFIGURATIONS AND POLE APPLICATIONS - Prestressed Concrete Transmission Pole Structures - page 3

Fig. 1-2. Single circuit cantilevered line post tangent structures
Source: Photograph courtesy of Valmont Newmark. Reproduced with
permission.
be single-pole or multipole structures depending on how the phase con-
ductors are oriented. Cantilevered structures, often called self-supporting
structures, are designed to withstand various combinations of vertical and
horizontal loads as an unsupported beam-column. Although shear and
torsion loads create stresses on the structure, the design of a cantilevered
structure is generally controlled by the bending stresses caused by hori-
zontal loads. Horizontal loads are usually the result of wire tension and
wind forces on the structure, equipment, and wires. Eccentric vertical
loads also contribute to bending stresses. Eccentric vertical loads can be
caused by equipment and conductor loads and by the vertical load of the
structure in a defl ected state.
Guyed Structures
Another category of prestressed concrete structures is guyed struc-
tures. To reduce the bending stresses associated with cantilevered struc-
tures, steel wire guys can be installed to transmit the horizontal loads
imposed on the structure to the ground. Although guys signifi cantly
reduce bending stresses in the structure, the vertical component of the