U.S. patent application number 11/011275 was filed with the patent office on 2005-06-09 for precast post-tensioned segmental pole system.
Invention is credited to Foster, E. Terence, Hansen, Audra L., Tadros, Maher K., Yehia, Sherif A..
Application Number | 20050120644 11/011275 |
Document ID | / |
Family ID | 26880047 |
Filed Date | 2005-06-09 |
United States Patent
Application |
20050120644 |
Kind Code |
A1 |
Tadros, Maher K. ; et
al. |
June 9, 2005 |
Precast post-tensioned segmental pole system
Abstract
A precast post-tensioned segmental pole system capable of
supporting a load is provided. The pole system includes a plurality
of pole segments that use connectors and strands to anchor them
together. The strands extend within a cavity formed in the pole
segments and are external to the wall structure of the pole
segments. The strands may be coupled between both of the pole
segments, or be anchored to a connector. The connector includes an
upper piece that is coupled to one pole segment, and a lower piece
that is coupled to the other pole segment. Upper and lower pieces
interlock with each other to join the pole segments to one another.
The strands are placed in tension so that pole system is capable of
withstanding forces imposed by the load.
Inventors: |
Tadros, Maher K.; (Omaha,
NE) ; Foster, E. Terence; (Omaha, NE) ; Yehia,
Sherif A.; (Omaha, NE) ; Hansen, Audra L.;
(Elkhorn, NE) |
Correspondence
Address: |
SHOOK, HARDY & BACON LLP
2555 GRAND BLVD
KANSAS CITY,
MO
64108
US
|
Family ID: |
26880047 |
Appl. No.: |
11/011275 |
Filed: |
December 13, 2004 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
11011275 |
Dec 13, 2004 |
|
|
|
10184349 |
Jun 27, 2002 |
|
|
|
6851231 |
|
|
|
|
60301189 |
Jun 27, 2001 |
|
|
|
Current U.S.
Class: |
52/155 ;
52/169.9 |
Current CPC
Class: |
E04C 5/08 20130101; E04C
3/26 20130101; E04C 3/34 20130101; E04H 12/16 20130101; E04C 3/22
20130101 |
Class at
Publication: |
052/155 ;
052/169.9 |
International
Class: |
E02D 027/00 |
Claims
What is claimed is:
1. A device for precasting a pole segment comprising: an external
mold comprising a bottom piece and a plurality of top pieces, said
top pieces being hingedly coupled with said bottom piece, said
bottom piece and said top pieces having inner surfaces defining a
channel; a yoke coupled to said top pieces; and an internal mold
having an outer surface, said internal mold adapted to be placed
within said channel to thereby define a cavity between said outer
surface of said internal mold and said inner surfaces of said
bottom piece and said top pieces, whereby said inner surfaces shape
an exterior surface of a pole segment and said outer surface of
said internal mold shapes an interior surface of said pole segment
when a formable material is placed between said external mold and
said internal mold.
2. The device of claim 1, further comprising an adjustable holding
mechanism that extends through said external mold and braces said
internal mold to hold said internal mold in position within said
channel.
3. The device of claim 3, wherein the adjustable holding mechanism
consists of at least one bolt.
4. The device of claim 1, wherein said internal mold includes top
and bottom pieces.
5. The device of claim 4 wherein said bottom piece is tapered along
its length.
6. The device of claim 4 wherein said top piece is tapered along
its length.
7. The device of claim 6, wherein a top portion of said top piece
is further tapered to form a thickened portion in the pole
segment.
8. The device of claim 7, further comprising at least one tube
coupled to said tapered portion of said internal mold.
9. A method for forming a pole segment used in a post-tensioned
pole system, said method comprising: providing an external form;
providing an internal form; placing said internal form within said
external form; securing said internal form within said external
form to thereby define a cavity between said internal form and said
external form; and placing a formable material within said cavity
to form the pole segment.
10. The method of claim 9 wherein the external form includes a
plurality of top pieces and a bottom piece.
11. The method of claim 10, wherein the top pieces are hingedly
coupled to said bottom pieces to form a channel.
12. The method of claim 11 further comprising providing at least
one adjustable holding mechanism coupled to the external form.
13. The method of claim 12 further comprising adjusting said
holding mechanism to secure internal form within said channel.
14. The method of claim 9, wherein said internal form is tapered to
form a thickened portion of the pole segment.
15. The method of claim 9 wherein said external form is tapered
along its length.
16. The method of claim 15, further including: providing at least
one tube; and coupling said tube to said tapered portion of said
internal mold prior to placing concrete mixture between said
external and internal forms to create an aperture in the thickness
portion of the pole segment.
17. A method for forming a pole segment used in a post-tensioned
pole system, said method comprising: providing a external form
having a plurality of top pieces and a bottom piece, said top
pieces being hingedly coupled to said bottom piece having inner
surfaces defining a channel; providing at least one adjustable
holding mechanism coupled to said external form; providing an
internal form with an outer surface; placing said internal form
within said channel to thereby define a cavity between said outer
surfaces of said internal form and said inner surfaces of said
bottom and top pieces; adjusting said holding mechanism so that
said internal form is secured within said channel; and placing a
concrete mixture within the cavity to form the pole segment.
18. The method of claim 17, wherein said internal form is tapered
to form a thickened portion of the pole segment.
19. The method of claim 18, further including: providing at least
one tube; and coupling said tube to said tapered portion of said
internal mold prior to placing concrete mixture between said
external and internal forms to create an aperture in the thickness
portion of the pole segment.
20. The method of claim 19 wherein said external form is tapered
along its length.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. patent
application Ser. No. 10/184,349, filed Jun. 27, 2002, which claims
benefit of U.S. Provisional Application No. 60/301,189, filed Jun.
27, 2001.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not Applicable.
BACKGROUND OF THE INVENTION
[0003] The present invention relates to a post-tensioned pole
system. In particular, the present invention relates to a
post-tensioned pole system includes one or more precast segments
which are coupled to one another by a connector and post-tensioned
through the use of at least one strand that is external to the wall
thickness of the pole segments.
[0004] It is well known that poles are used in a wide variety of
applications including electrical transmission and distribution
environments, lighting, telecommunications and as supports for wind
energy turbines. When used in these environments, the poles are
subjected to forces from the wind, water and structural loads such
as the weight of wire transmission lines or a wind turbine. These
forces create a moment or torque that the pole must resist in order
to remain in an upright position. In resisting these forces, the
pole has a tendency to flex thereby putting the bottom portion of
the pole in compression and the top portion of the pole in
tension.
[0005] In the past, the poles have been formed of various materials
such as steel, wood, concrete, masonry materials and any
combination thereof. The use of concrete to form the poles is
relatively common due to its availability. However, the use of
concrete to form the poles suffers from a number of drawbacks. For
instance, while concrete is capable of withstanding a substantial
amount of compression force, its ability to resist tension is
considerably low. Therefore, different techniques have been
established in an effort to enhance the concretes ability to
withstand the tension forces imposed on the pole.
[0006] One technique used to enhance the ability of the concrete to
withstand tension forces is pre-tensioning. Pre-tensioning the
concrete has been accomplished by embedding strands within the
concrete walls of the concrete using a spun or static cast
technique. In the static cast method, the strands are arranged
within the form prior to pouring the concrete. Both ends of each
strand are jacked to place the strands in tension. The concrete is
then placed into the form embedding the strands therein. The
strands are cut after the concrete has gained adequate strength,
releasing the force to the concrete. The tension in the strands
places the concrete pole into compression thereby allowing it to
withstand a greater amount of tension force. The spun cast
technique is similar to the static method in that the strands are
placed in the form prior to the addition of the concrete. However,
instead of placing the concrete into a static form, the concrete is
poured into a machine that spins the concrete forcing the concrete
to the outer walls of the form and embedding the strands within the
wall of the structure.
[0007] The aforementioned pre-tensioning techniques also suffer
from a number of deficiencies. One problem with the spun cast
method is that the concrete aggregate separates due to centrifugal
force thereby making concrete weak and susceptible to cracking due
to unequal distribution of aggregate. In addition, the equipment
used to spin the concrete is expensive. In addition, both of the
aforementioned methods of pre-tensioning concrete poles are
problematic in that it takes a considerable amount of time to
properly position the strands in the form prior to pouring the
concrete.
[0008] Additionally, there other problems associated with current
concrete pole structures. For example, the concrete structures that
are used in these environments are typically unitary structures
that extend to a height of about 80-90 feet. This is problematic
because certain power transmission line applications may require
the poles to extend to greater heights. Additionally, given the
fact that poles are a unitary structure, it is very difficult to
transport the pole structures from an off-site location to the
construction site. Once the poles arrive at the site, they require
large cranes and heavy machinery to lift them into position due to
the weight and length of the pole.
[0009] Accordingly, there remains a need for a segmental
post-tensioned pole system that increases maximum height of pole
while reducing the difficulty in transporting the pole from
off-site location to the construction site. In addition, there is
also a need to simplify the installation and manufacture of the
pole. The present invention fills these needs as well as various
other needs.
BRIEF SUMMARY OF THE INVENTION
[0010] In order to overcome the above-stated problems and
limitations, and to achieve the noted objects, there is provided a
precast post-tensioned segmental pole system that is capable of
supporting a load and withstanding other external forces.
[0011] In general, the pole system includes several pole segments
with similar connectors anchoring them together. For example, the
first and second pole segments each have top and bottom ends with a
cavity formed therein. The connector is adapted to couple the top
end of the first pole segment with the bottom end of the second
pole segment. The connector includes upper and lower pieces. The
upper piece includes a channel band coupled to the second pole
segment and having an inner edge. The connector further includes a
stiffener being disposed within the channel band. The lower piece
includes a base plate coupled to the first pole segment and a cover
plate coupled to the base plate and having an outer edge that is
adapted to interlock with an inner edge of the upper piece. The
strands are placed in tension and can either continue through or be
anchored at any of the segment connectors.
[0012] Additionally, the pole system may also include an anchor
that couples the anchored strand to the connector. The anchor may
include a cylinder, a clasping mechanism slidably received within
the cylinder, a pipe coupled to the cylinder and a spring mounted
within the pipe. The spring retains the clasping mechanism within
the cylinder when the strand is coupled when the clasping mechanism
is releasably coupled to the anchored strand.
[0013] Further objects, features, and advantages of the present
invention over the prior art will become apparent from the detailed
description of the drawings which follows, when considered with the
attached figures.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0014] In the accompanying drawings which form a part of the
specification and are to be read in conjunction therewith and in
which like reference numerals are employed to indicate like parts
in the various views:
[0015] FIG. 1 is an elevational view of a post-tensioned segmental
pole system according to the present invention;
[0016] FIG. 2 is a cross-sectional view taken along line 2-2 of
FIG. 1 showing a connector mounted to a pole segment;
[0017] FIG. 3 is a cross-sectional view taken along line 3-3 of
FIG. 2 showing a plurality of strands extending within the cavity
of the pole segment;
[0018] FIG. 4 is an enlarged view of the area encompassed by "4" in
FIG. 3 showing the connector mounted between two pole segments;
[0019] FIG. 5 is an enlarged view of the area encompassed by "5" in
FIG. 4 showing an anchor coupled to a strand;
[0020] FIG. 6 is a perspective view showing an upper piece of the
connector mounted to a pole segment;
[0021] FIG. 7 is a perspective view of an external form used to
form the external shape of a pole segment;
[0022] FIG. 8 is an elevational view of the external mold with an
internal mold positioned therein;
[0023] FIG. 9 is an elevational view of the external mold showing a
top piece rotating about a hinge point as illustrated in dashed
lines;
[0024] FIG. 10 is an elevational view of the internal mold having a
tapered top piece; and
[0025] FIG. 11 is an elevational view of an internal mold similar
to FIG. 10 having a non-tapered top piece.
DETAILED DESCRIPTION OF THE INVENTION
[0026] Referring now to the drawings in detail, and initially to
FIG. 1, numeral 10 generally designates a post-tensioned segmental
pole system constructed in accordance with a first preferred
embodiment of the present invention. Pole system 10 may include one
or more pole segments 12 coupled to one another by a connector 14
to form a monopole structure. As best seen in FIG. 3, pole system
10 also includes a plurality of strands or tendons 16 that extend
through a hollow interior cavity 18, and which are external to pole
segment 12. Strands 16 are placed under tension and coupled between
pole segments 12.
[0027] Pole system 10 may be used to support a load such as a
structural appurtenance, insulator anchor, antenna in various types
of service environments including, but not limited, to electrical
transmission and distribution, lighting, communications and wind
power generation. In addition, pole system 10 may also withstand
external forces such as, but not limited to, wind, water and the
like. It will be understood that a number of pole systems may be
used in conjunction to form a multi-pole system to increase the
height capability of pole system 10. For instance, a number of pole
systems may be arranged in a tripod configuration to provide
support for a single pole system that would extend upwardly from
the apex of the tripod. This configuration would essentially double
the overall height capabilities of the present invention.
[0028] As best seen in FIG. 1, pole system 10 may include one to
four pole segments 12 that may form a monopole structure of up to
120 feet (36 meters). With additional reference to FIGS. 2 and 3,
each pole segment 12 may be approximately 30 feet (9 meters) in
length having a tapered hexagonal cross-section. It is desirable to
use a pole segment 12 having a cross-section that has stiffness
characteristics that are independent of lateral applied loads such
as, but not limited to, wind or wave forces. Therefore, it is
preferable to use a pole segment 12 having a radial symmetrical
cross-section with a flat outer surface 20 so that appurtenances
may be fastened to pole segment 12. Although a hexagonal
cross-section is described and shown herein, it is within the scope
of the present invention to use a pole segment 12 having
cross-section in the shape of an octagon or any other radially
symmetric cross-sectional shape.
[0029] As best seen in FIG. 1, outer surface 20 of pole segment may
be tapered at the rate of 1 inch (25 mm) over a distance of 10 feet
as pole segment 12 extends from a bottom portion 22 to a top
portion 24. As best seen in FIGS. 3 and 4, an inner surface 26 of
pole segment 12 also tapers inwardly at approximately the same rate
as outer surface 20 and defines hollow interior cavity 18. Top
portion 24 of inner surface 26 may include a thickened portion 28
where inner surface 26 tapers inwardly at a greater rate compared
to bottom portion 22 of inner surface 26. Thickened portion 28 may
begin at an intermediate portion of inner surface 26 and extend to
a rim 30 at top portion 24. Further, a plurality of apertures 32
are formed in inner surface 26 and extend through thickened portion
28 to a top surface 34 of pole segment 12. Apertures 32 are
hexagonally disposed within hollow interior cavity 18 and adapted
to allow strands 16 to pass therethrough. The number of apertures
32 formed in segment 12 preferably corresponds with the number of
strands 16 extending within cavity 18.
[0030] Pole segments 12 may be formed of various types of concrete
including, but not limited to, high performance concrete (HPC)
which is capable of higher than normal compressive strengths. High
performance concrete utilizes fibers that are used to reinforce the
concrete instead of using standard reinforced bars to enhance the
concrete strength. The high performance concrete may have a minimum
compressive strength of 8000 pounds per square inch, a RCP factor
of 1000 coulombs, and a minimum freeze-thaw capacity for cold
weather environments. However, pole system 10 may also utilize
reinforcement bars or welded wire fabric within the walls of pole
segments 12 to increase the strength of pole segment 12.
[0031] As best seen in FIG. 1, connector 14 is used to couple two
pole segments 12 to one another. As best seen in FIG. 4, connector
14 includes an upper piece 36 and a lower piece 38. Upper piece 36
includes a channel band 40 and a plurality of studs 42. Studs 42
are mounted within bottom portion 22 of pole segment 12. With
additional reference to FIG. 6, channel band 40 includes top and
bottom plates 44, 46, a cross piece 48 and a stiffener 50. Top
plate 44 is fixedly coupled to studs 42 and extends inwardly
towards cavity 18. Cross piece 48 extends downwardly from top plate
44 and is coupled to bottom plate 46. Bottom plate 46 extends
inwardly and parallel with top plate 44. As best seen in FIGS. 2
and 6, bottom plate has a inner edge 52 that is adapted to
interlock with lower piece 38. Although, inner edge 52 is in the
shape of a hexagon, it should be understood that it may be formed
in any shape that will allow it to interlock with lower piece 38.
Stiffeners 50 extend between top and bottom plates 44, 46 and are
used to stiffen channel band 40.
[0032] As best seen in FIGS. 2 and 4, lower piece 38 is mounted to
top portion 24 of pole segment 12 and is used to interlock with
upper piece 36. Lower piece 38 includes a cover plate 54, a base
plate 56 and studs 58. Studs 58 are mounted within top portion 24
of pole segment and is fixedly mounted to base plate 56. Base plate
56 is a hexagonal ring and has a support surface 60. Cover plate 54
is also a hexagonal ring and mounted to a portion of a support
surface 60 on base plate 56. Further, cover plate 54 includes an
outer edge 62 adapted to interlock with inner edge 52 of channel
band 40. Although outer edge 62 is shaped in the form of a hexagon,
it should be understood and appreciated that outer edge 62 may be
other shapes that will allow it to interlock with inner edge 52 of
channel band 40. Outer edge 62 is sized so that there is a gap 64
between inner edge 52 and outer edge 62. However, gap 64 is small
enough that the rotation between channel band 40 and cover plate 54
is minimized. Cover plate 54 also includes a rim 66 that may be
aligned with rim 30 formed in top portion 24 of pole segment 12.
Further, as best seen in FIG. 5, cover plate 54 has a plurality of
holes 68 formed therein that are aligned with apertures 32 formed
in thickened portion 28 so that strands 16 may pass therethrough.
With reference to FIGS. 2 and 5, cover plate 54 also has a top
surface 70 where one or more strand anchors 72 may be mounted
thereon which will be described more fully below.
[0033] The post-tensioning of pole system 10 is accomplished
through the use of a plurality of strands 16 that extend within
hollow interior cavity 18, but which are external to the walls of
pole segments 12. Strands 16 are adapted to be placed in tension so
that pole segments 12 in pole system 10 are capable of withstanding
an increased amount of tensile force. Strands 16 may be 0.5 inches
(12 mm) in diameter and arranged within cavity 18 as shown in FIGS.
2 and 3. In particular, strands 16 may be arranged in repeats on
each of the side of the hexagonal cross-section of pole segment 12
so the resulting radial symmetry provides relatively constant
moments of inertia for flexural stiffness independent of lateral
force direction. With specific reference to FIG. 4, strands 16 may
extend through thickened portion 28 to ensure that strands 16 are
positioned near inner surface 26 to allow them to make a maximum
contribution to flexural stiffness. One strand 16 may extend from
bottom portion 22 and be coupled to top end 22, 24 of the same pole
segment 12. In addition, strand 16 may also extend from bottom
portion 22 of a base pole segment 12 to a top portion 24 of a pole
segment positioned on top of the base pole segment. Further,
strands 16 may continue to extend to a pole segment further up the
pole system 10.
[0034] As best seen in FIGS. 2 and 5, strands 16 are coupled to top
portion 24 of pole segment 12 through the use of at least one
anchor 72. Specifically, anchor 72 rests against top surface 70 of
cover plate 54 and prevents strand 16 from being pulled downwardly
towards bottom portion 22 of pole segment 12. Anchors 72 include a
cylinder 74 having a clamping mechanism 76 slidably coupled within
an interior portion of cylinder 74. Clamping mechanism 76 is a
two-piece jaw structure having a variable diameter hole formed
therein. The hole is tapered as it extends through the jaws and has
one or more teeth or protrusions extending therein to grip and hold
onto strand 16. Anchor 72 further includes a pipe 78 with a helical
spring 80 fixedly mounted therein. Pipe 78 is fixedly mounted to
the top ring of cylinder 74 and spring 80 is positioned to bias
jaws 76 toward top surface 70 of cover plate 54.
[0035] In operation, pole system 10 may be a single pole segment 12
used alone, or in combination with one or more pole segments. A
single or monopole system may extend to a height of 30 feet.
Therefore, a system with four pole segments may extends to a height
of 120 feet. Furthermore, a tripod system may extend to a height of
approximately 240 feet. If one pole segment 12 is used by itself as
the supporting structure, strands 16 are fed through hollow
interior cavity 18 of pole segment and threaded through apertures
32 and holes 68 in cover plate 54 as best seen in FIGS. 3 and 4.
Referring now to FIG. 5, a portion of each strand 16 that extends
through holes 68 is coupled to anchor 72. In particular, strand 16
is pushed upwardly against jaws 76 to place the end portion of
strand 16 within the hole formed between jaws 76. As strand 16 is
being pushed upwardly, jaws 76 slide upwardly to compress spring
80. Spring 80 prevents the jaws 76 from being dislodged from
cylinder 74. The angled portion of the jaws slides along an inner
edge of cylinder 74 and the jaws splits apart. Once jaws 76 open
enough to allow strand 16 to enter the inner diameter, the upward
force on strands is release and spring 80 biased jaws 76 downwardly
so that the hold formed between the jaws decreases and the teeth
within the hole grips onto strand 16. The remaining strands 16 are
coupled to top portion 24 of pole segment in a similar fashion.
Strands 16 then proceed to extend downwardly to bottom portion 22
of pole segment 12. Bottom portion 22 of pole segment 12 is placed
in a foundation hole and backfill such as compact fill, flowable
concrete mix or reinforced concrete is added to the hole to support
pole segment 12. Strands 16 are placed in tension by jacking or by
other conventional methods to complete the post-tensioned pole
system 10.
[0036] Two or more pole segments 12 may also be used to form pole
system 10. Strands 16 are first fed through hollow interior cavity
18 of the bottom or base pole segment and external to the pole
segment structure 12. Strands 16 are threaded through apertures 32
and holes 68 in cover plate 54. Some of strands 16 are then coupled
to top surface 70 of cover plate 54 by anchors 72 as described in
detail above. The remaining strands continue to extend through the
hollow interior cavity 18 of the second pole segment. Bottom plate
48 is placed on support surface 60 and inner edge 52 is interlocked
with outer edge 62 as best seen in FIGS. 2 and 4. Thus, the second
pole segment is resting on top of the bottom or base pole segment.
The remaining strands 16 are threaded through apertures 32 and
holes 68 in cover plate 54 of the second pole segment.
[0037] All the remaining strands 16 may be coupled to cover plate
54 of the second pole segment by using strand anchors 72, or in the
alternative, some strands 16 may be coupled to cover plate 54 while
the remaining strands 16 continue to extend to a third pole
segment. This process may continue in a similar fashion as
described above until the desired height is achieved. For example,
in a four pole system as shown in FIG. 1, thirty-six strands may
extend within the cavity 18 of a bottom or base pole segment. At
the juncture between the base segment and second segment, twelve of
those strands may be mounted to cover plate on the base segment and
twenty-four would continue to extend within cavity of the second
pole segment. The juncture between the second and third pole
segments is best shown in FIGS. 2 and 3. At this juncture, twelve
of those strands may be mounted to cover plate 54 of the second
pole segment and twelve would continue to extend within cavity 18
of the third pole segment. At the juncture between the third and
fourth pole segments, six of those strands may be mounted to cover
plate of the third pole segment and six would continue to extend
within cavity of the fourth pole segment. Finally, the six
remaining strands would then be coupled to the cover plate of the
fourth pole segment. It will be understood that the joining of pole
segments 12 and strands 16 may be conducted on the ground so the
pole segments extend in a horizontal direction, or may be stacked
on top of each other for vertical construction. Regardless of the
number of strands in pole system 10, strands 16 in the
multi-segmented construction are then placed in tension to create a
post-tensioned pole system 10 and placed in the appropriate
foundation as described above. In addition, concrete may then be
poured through rims 30, 66 into hollow interior portion 18 in
either the single or multi-pole segment structures to create a
solid pole structure.
[0038] The present invention further includes a mold unit 82 that
may be used to precast pole segments 12 that are used in pole
system 10 as best seen in FIG. 8. Mold unit 82 includes an external
mold 84, internal mold 86 and a yoke 88. Mold unit 82 shown in the
accompanying drawings is an example of a typical mold structure,
and it will be understood that the proportions of the molds may
vary depending on where the pole segment will be located in the
pole system 10. For instance, a pole segment that will be
positioned at the base or bottom of pole system will be much larger
than a mold for a segment that will be positioned at the upper
portions of pole system 10.
[0039] As best seen in FIG. 7, external mold 84 includes a bottom
piece 90 and a pair of top pieces 92. In particular, top pieces 92
are coupled to bottom piece 90 by a set of hinges 94 which allow
external mold 84 to be placed in closed and open positions. As best
seen in FIG. 7, external mold 84 is in a closed position where
bottom piece 90 and top pieces 92 are arranged to form a channel 96
which will define the outer surface 20 of pole segment 12. In
addition, channel 96 may also taper inwardly along the longitudinal
axis of external mold 84. As best seen in FIG. 9, top pieces 92 may
be rotated outwardly about hinges 94 so that external mold 84 is in
the open position so that pole segment 12 may be removed from
external mold 84. As best seen in FIG. 8, external mold 84 also has
a plurality of bolts 98 adjustably mounted within bottom piece 90.
Bolts 98 are mounted within bottom piece 90 so that a portion of
each bolt 98 can be independently adjusted to extend variable
distances within channel 96 and contact internal mold 86. It is
also within the scope of this invention to include bolts 98 in top
pieces 92. Yoke 88 is removably coupled to a top surface 98 top
pieces 92 and has a bolt 100 mounted thereto that is adapted to
extend within channel 96 and contact internal mold 86. Yoke 88 is
used to prevent top pieces 92 from floating or rotating relative to
bottom piece 90 when the concrete is placed within mold unit
82.
[0040] As best seen in FIG. 10, internal mold 86 is tubular member
having a top piece 102, a bottom piece 104 and a plurality of tubes
106. With additional reference to FIG. 8, bottom piece has an outer
surface 108 that has a similar taper compared to channel 96, but is
sized so there is a space between channel 96 and outer surface 108.
Further, a collar 110 removably couples bottom piece 104 to top
piece 102. An outer surface 112 of top piece 102 extends upwardly
from collar 110 at the same taper as bottom piece 104 and then
proceeds to narrow even further as it extends toward a rim 114. The
increased taper towards the top portion of top piece 102 creates a
larger space between channel 96 and outer surface 112 to allow for
the formation of thickened portion 28 as seen in FIG. 4. Tubes 106
are used to form apertures 32 in thickened portion 28 of pole
segment 12. In particular, tubes 106 are mounted to top piece 102
and extend outwardly therefrom in a direction parallel to the
longitudinal axis of top and bottom pieces 102, 104. The distal
ends of tubes 106 are tapered to make it easier to remove tubes
with top and bottom pieces 102, 104 after the concrete hardens.
[0041] As best seen in FIG. 11, top piece 102 may also have a
uniform taper that is similar to bottom piece 104 as it extends
from collar 110 to rim 114. To change top pieces 102, collar 110 is
loosened, and the new top piece is slid onto bottom piece 104.
Collar 110 is tightened and the change is complete. The uniform
taper in top piece 102 results in a pole segment 12 with uniform
wall thickness along its entire length. In this case, there would
be no thickened portion 28 or apertures formed in pole segment 12
since strands 16 may pass through hollow interior cavity 18 without
interfering with the walls of pole segment 12.
[0042] In forming a pole segment using mold unit 82, top pieces 92
on external mold 84 are rotated outwardly about hinges 94 to an
open position. As best seen in FIG. 8, internal mold 86 is then
placed within channel 96 and supported by bolts 100. Bolts 100 are
adjusted in such a manner so that there is an equal amount of space
between channel 96 and outer surfaces 108, 112 of internal mold 86.
Top pieces 92 are then moved to the closed position. Yoke 88 is
then placed on top surface 98 and is coupled to each top piece 92
to prevent top pieces 92 from rotating outwardly relative to bottom
piece 90. Concrete is then poured between channel 96 and outer
surfaces 108, 112. After the concrete cures, internal mold 86 is
removed from the hardened pole segment 12 thereby forming hollow
interior cavity 18 and apertures 32. Yoke 88 is then removed from
top pieces 92 and top pieces 92 are moved to the open position.
Pole segment 12 may them be removed from external mold 84 and used
in pole system 10. It should be understood that pole segments may
be formed either at an off-site location or a construction
site.
[0043] It can, therefore, be seen that the invention is one that is
designed to overcome the drawbacks and deficiencies existing in the
prior art. The invention provides a pole system that includes one
or more pole segments that are post-tensioned by strands that are
positioned within a hollow interior cavity and external to the wall
structure of the pole segments. The use of separate pole segments
to form the pole system reduces the difficulty in transporting the
components of the pole system. Each pole segment is relatively easy
to maneuver and lift through the use of a crane, winch system, or
helicopter to simplify installation. In addition, the fact that the
strands are positioned within the hollow interior cavity of the
pole segment reduces the amount of time it takes to manufacture the
pole segments since each strand does not have to be positioned
within the form prior to pouring the concrete in the form. Further,
the connectors provided in the present invention simplify the
process of coupling two pole segments to one another. Additionally,
the forms of the present invention eliminates the need to purchase
expensive spinning equipment for forming pole segments having a
interior cavity.
[0044] While particular embodiments of the invention have been
shown, it will be understood, of course, that the invention is not
limited thereto, since modifications may be made by those skilled
in the art, particularly in light of the foregoing teachings.
Reasonable variation and modification are possible within the scope
of the foregoing disclosure of the invention without departing from
the spirit of the invention.
* * * * *