Method and apparatus for increasing the capacity and stability of a single-pole tower
A support structure for use with an existing single pole tower and a method for supporting additional loading of the existing pole tower are disclosed. The single pole tower has a pole anchored to an existing foundation and supports a first load. The support structure has a number of sleeves surrounding the pole with a bottom sleeve anchored to a new foundation surrounding the existing foundation. Load transfer plates are disposed between the existing tower and sleeves and load transfer bolts extending through the sleeves are torqued against the load transfer plates for stabilizing the loaded tower. One or more additional loads may be attached to one of the sleeves.
This application is related to application Ser. No. 09/557,266 filed on Apr. 24, 2000, the disclosure of which is hereby incorporated by reference. This application is a continuation in part of application Ser. No. ______, filed Oct. 26, 2001, entitled Method and Apparatus for Increasing the Capacity and Stability of a Single-Pole Tower, which is a continuation of the aforementioned application Ser. No. 09/557,266.
TECHNICAL FIELDThe present invention relates generally to a method and an apparatus for increasing the capacity and stability of a single-pole tower. More particularly, the invention relates to a method and an apparatus that employs a sleeve and an array of load transfer plates to improve load distribution and add structural stability to a single-pole tower and thereby increase its capacity to support additional equipment and withstand environmental loads.
BACKGROUND OF THE INVENTIONThe increase in wireless telecommunications traffic has resulted a concomitant increase in the need for pole-mounted transmission equipment of all kinds. Not only do wireless service providers need to install equipment covering new geographic areas, competing service providers and others also need to install additional equipment covering the same or similar geographic areas. To date, the solution to both problems normally includes purchasing additional land or easements, applying for the necessary government permits and zoning clearances, and constructing a new tower for the new transmission equipment.
Purchasing land or easements, however, is becoming increasingly expensive particularly in urban areas where the need for wireless telecommunications is greatest. Zoning regulations often limit the construction of new towers in the vicinity of existing towers or may prohibit the construction of new towers in the most suitable locations. The expense and delay associated with the zoning process often may be cost-prohibitive or so time-consuming that construction of the new tower is not feasible. Even when zoning regulations can be satisfied and permits can be obtained, the service provider must then bear the burden and expense associated with the construction and the maintenance of the tower.
The tower itself must be designed to support the weight of the telecommunications transmission equipment as well as the forces exerted on the pole by environmental factors such as wind and ice. The equipment and the environmental factors produce forces known as bending moments that, in effect, may cause a single-pole tower to overturn if not designed for adequate stability. Traditionally, single-pole towers have been designed to withstand the forces expected form the equipment originally installed on the pole. Very few single-pole towers, however, are designed with sufficient stability to allow for the addition of new equipment.
Thus, there is a need for a method and an apparatus for increasing the capacity and stability of a single-pole tower that will support the weight of additional equipment and support the additional environmental forces exerted on the pole. The prior art shows various brackets used for restoring the strength of a weakened or damaged section of a wooden pole. An example of a known pole restoration system is shown in U.S. Pat. No. 4,991,367 to McGinnis entitled, “Apparatus and Method for Reinforcing a Wooden Pole.” This reference describes an apparatus that employs a series of braces linked together around the circumference of a tapered pole. The braces are then forced downward on the pole to wedge the assembly tightly against the pole to provide support. This system does not include an anchorage to the ground or base of the pole.
A number of other known restoration systems employ a first part attached to the damaged section of the pole and a second part that is driven into the ground to provide support. An example of such a system is shown in U.S. Pat. No. 4,756,130 to Burtelson entitled, “Apparatus for Reinforcing Utility Poles and the Like.” This apparatus uses a series of brackets and straps attached to ground spikes. Another example of a known pole restoration system is shown in U.S. Pat. No. 4,697,396 to Knight entitled, “Utility Pole Support.” This reference describes an apparatus with a series of brackets attached to a wooden utility pole. A series of tapered spikes are anchored on the brackets and then driven into the ground to provide support. Additional examples of such a system are shown in U.S. Pat. Nos. 5,345,732 and 5,815,994, both issued to Knight & Murray, entitled “Method and Apparatus for Giving Strength to a Pole” and “Strengthening of Poles,” respectively. These references describe an apparatus with a nail or bridging beam driven through the center of the wooden pole. The nail is attached by linkages to a series or circumferential spikes that are then driven into the ground to provide support.
In each of these systems, the brackets are fixable attached to a damaged wooden utility pole to provide a firm anchor for the ground spikes. The spikes are driven into the ground immediately adjacent the pole to wedge the spike tightly against the side of the pole. The functionality of each of these systems depends, therefore, on the rigid attachment between the pole brackets and the spikes as well as the compression fit of the spikes between the ground and the pole. Further, these ground based systems only function when the damaged pole section is sufficiently near the ground for the bracket assembly to be attached to the ground spikes. The capacity of these known systems to resist bending moments is dependent upon the height of the damaged section relative to the ground as well as the characteristics of the soil and other natural variables. Moreover, each of these systems describes an apparatus for the purpose of restoring a damaged pole to its original capacity, not for the purpose of bolstering an existing pole to increase its capacity.
A support structure for supporting a load is shown in the aforementioned Ser. No. 09/557,266. The support structure includes a single pole tower and a sleeve surrounding the pole. The pole and the sleeve are anchored to an existing foundation, with the sleeve supporting a load. An additional cross-beam may be anchored to a new foundation that surrounds the existing foundation and be anchored at diametrically opposite sides for additional support. A number of sleeves may be used with a first sleeve anchored to the foundation, a second sleeve supporting the load, and one or more joinder sleeves positioned between the first sleeve and the second sleeve. The pole also may support a second load. The total height of the number of sleeves may extend beyond the height of the existing single pole tower. A number of load transfer pins are positioned along at least one of the sleeves. The pins extend from the inside of the sleeve to the pole and apply pressure against the outer surface of the tower.
This structure may suffer from several disadvantages. Due to the point contact of the pins against the outer surface of the tower, such towers have limited capacity for increased loads. Each load transfer pin concentrates the force and may readily damage the pole when tightened. Further, as more load is added to the pole, the original foundation as well as the cross-beams anchored to the new foundation may be inadequate for increased bending moments. Further, the use of pipe sections and welded sleeve tabs are labor intensive and require close check that proper welds are made to preclude failure upon application of bending moments.
Thus, there remains a need for a method and apparatus for increasing the capacity and stability of a single-pole tower that will support the weight of additional equipment and support the additional environmental forces exerted on the pole, while providing sufficient stability to resist the forces known as bending moments exerted by the new equipment and the environmental forces. Such a method and an apparatus should accomplish these goals in a reliable, durable, low-maintenance, and cost-effective manner.
SUMMARY OF THE INVENTIONThe present invention provides an improved method and an apparatus for increasing the capacity and stability of a single-pole tower.
In accordance with the present invention, there is a support structure for retrofitting an existing single pole tower which has a pole anchored to an existing foundation and supports a first load. The support structure has a number of sleeves surrounding the pole that may extend beyond the height of the existing single pole tower. A second load is attached to an upper sleeve. Additional loads may be attached to one or more of the sleeves. The loads may include one or more telecommunications arrays.
In accordance with another feature of the present invention, a first sleeve is anchored to a new foundation surrounding the existing foundation and load transfer plates are interposed between at least one of the sleeves and the outer surface of the existing single pole tower.
In accordance with the aforementioned application Ser. No. 09/557,266 and the invention described therein, the sleeves are made out of metal such as a structural pipe with a minimum yield stress of about 42 ksi. The sleeves may have a first half and a second half. Each half may have a first side with a first sleeve tab and a second side with a second sleeve tab. The sleeve tabs may have a number of apertures positioned therein. There may be a number of sleeves, such as a first sleeve, a second sleeve, and a third sleeve. The sleeves also may include a first end with a first top flange plate and a second end with a second bottom flange plate. The second bottom flange plate of the first sleeve is anchored to the existing foundation. The flange plates also may have a number of apertures positioned therein. As described in application Ser. No. 09/557,266, the sleeves include a number of load transfer pins. The load transfer pins may have a bolt and one or more nuts. The pins extend from the sleeves to the pole so as to stabilize the loads. The pins may be radially spaced around a vertical center axis of the sleeves. The sleeves may include a plurality of access ports positioned therein.
In accordance with the present invention, sleeves are made of structural plates with a minimum yield stress of about 65 ksi formed in a break press. There may be a number of sleeves, such as a first sleeve, a second sleeve, and a third sleeve. The sleeves may have multiple polygonal sections to enclose the pole. Each section has vertical flanges formed in the press. The sleeves also may include a first end with a first top flange plate and a second end with a second bottom flange plate. Preferably, the first sleeve, however, has a base plate at the second lower end for anchoring of the tower to the foundation. Preferably, a number of load transfer plates are associated with the sleeves. The load transfer plates may have a number of retention rods. A number of bolts are threaded through associated nuts that are welded to the sleeves. The bolts extend from the sleeves and press against the plates to stabilize the existing pole. The load transfer plates may be radially spaced around a vertical center axis of the sleeves.
In accordance with the present invention, the base plate of the first sleeve is anchored to a new foundation surrounding the existing foundation by means of anchor bolts. The first flange plate of the first sleeve may include a dimension to accommodate the second flange plate of the second sleeve while the first flange plate of the second sleeve may include a dimension to accommodate the second flange plate of the third sleeve. The first end of the third or uppermost sleeve, as the case may be, may include a cover plate.
One embodiment of the present invention provides a support structure that surrounds an existing single pole tower: The existing single pole tower is anchored to an existing foundation and supports a first load. The support structure includes sleeves that surround the existing single pole tower. A first sleeve with a base plate attaches to a new foundation that surrounds an existing foundation. A second sleeve is attached to the first sleeve and may support a second load. The second sleeve may be attached to the first sleeve via one or more joinder sleeves. One or more sleeves include associated load transfer plates. The existing single pole tower may be larger in height than the surrounding sleeves, and may support additional loads.
A second embodiment of the present invention relates to a method that allows for additional loading to be placed on a single pole tower. The single pole tower includes a pole anchored to an existing foundation. The method includes the steps of surrounding the existing foundation with a new foundation, positioning one or more sleeves around the pole, anchoring one of the sleeves to the new foundation, and supporting the additional load on the sleeves. A first one of the number of sleeves may be anchored to the new foundation, a second one of the sleeves may be supporting an additional load, and one or more joinder sleeves may attach the first and the second sleeves. The method may further include the step of attaching a number of load transfer plates to the sleeves so as to distribute and stabilize the additional load.
Thus, it is an object of the present invention to provide an improved method and apparatus for retrofitting an existing single pole tower to increase the capacity and stability of a single-pole tower.
It is another object of the present invention to provide an improved method and apparatus for increasing the capacity and stability of a single-pole tower wherein the apparatus will support the weight of additional equipment and the additional environmental forces exerted on the pole.
It is still another object of the present invention to provide an improved method and apparatus for increasing the capacity and stability of a single-pole tower wherein the apparatus will support the weight of additional equipment and the additional environmental forces exerted on the pole while also providing sufficient stability to resist the forces known as bending moments caused by the new equipment and the environmental forces.
Other objects, features, and advantages of the present invention will become apparent upon reading the following detailed description of the preferred embodiment of the invention when taken in conjunction with the drawings and the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
Referring now in more detail to the drawings, in which like numerals indicate like elements throughout the several views,
As is shown in
The vertical flanges 190, 200 may have a plurality of aperture or bolt holes 210 therein that align so as to connect the respective sections 120, 130 by bolts 215 or other conventional types of fastening means. The bolts 215 preferably should comply with ASTM A-325 standards and are typically 1½ inches. When joined along the vertical flanges 190, 200, the sections 120, 130 of the sleeves 110 form a largely hollow structure with a diameter slightly greater that the greatest diameter of that section of the pole 20 the particular sleeve 110 is intended to surround.
The sections 120, 130 may have a first flange plate 220 encircling the top portion 170 of both sections 120, 130 and a second flange plate 230 encircling the bottom portion 180 of both sections 120, 130. The flange plates 220, 230 are welded to the sections 120, 130 and may also be made from hot-dipped galvanized ASTM 572 structural plate or similar materials. All welds of the present invention should preferably comply with AWS A5.1 or A5.5, E80xx standards. The width of the flange plates 220, 230 may vary so as to accommodate the additional sleeves 110 of varying size. The flange plates 220, 230 may have a plurality of apertures or bolt holes 240 therein so as to connect the sleeves 110 by a number of bolts 245 or by other conventional types of fastening means as described in more detail below. The bolts 245 should comply with ASTM A-325 standards and are typically 1¼ inches. Several gussets 300 are welded to each flange plate 220, 230, as well as base plate 280 and to the corresponding sleeve 110 for stiffening.
In accordance with the present invention, a number of load transfer plates 310 are positioned along the length of sleeve 350 of support structure 100 as shown in
The sleeves 110 also may have one or more access ports 340, shown in
As most clearly shown in
Referring again to
The third sleeve 350, or whichever sleeve 110 is positioned on top, may be sealed at the top with a cover plate 370. The cover plate 370 extends in a close fit from the perimeter of the existing pole 20. The cover plate 370 may be sealed in a watertight fashion with a silicon sealant. The cover plate 370 may be constructed of ¼-inch steel, such as hot-dipped galvanized ASTM 572 structural plate or similar materials. The cover plate 370 may be welded to the top portion 170 of the third sleeve 350.
For example, in a typical five (5) sleeve 110 embodiment, a first sleeve 250 may have a height of about 40 ft., a width of about 52 in. at the bottom portion 180, a width of about 44 in. at the top portion 170, and a thickness of about ⅜ in; a first joinder sleeve 360 may have a height of about 40 ft., a width of about 44 in. at the bottom portion 180, a width of about 37 in. at the top portion 170, and a thickness of about ⅜ in; a second joinder sleeve 360 may have a height of about 23 ft., a width of about 37 in. at the bottom portion 180, a width of about 32 in. at the top portion 170, and a thickness of about ¼ in; a third joinder sleeve 360 may have a height of about 15 ft., a width of about 32 in. at the bottom portion 180, a width of about 30 in. at the top portion 170, and a thickness of about ¼ in; a top sleeve 350 that is associated with the load transfer plates 310 may have a height of about 8 ft., a width of about 36 in. at the bottom portion 180, a width of about 32 in. at the top portion 170, and a thickness of about ⅜ in.
One or more telecommunications arrays may be positioned on the support structure 100. The telecommunication arrays may be of conventional design and may be identical to an existing telecommunication array. The telecommunication arrays may be attached to the support structure 100 by bolts or by other conventional types of attachment means. As is shown in
In use, the support structure 100 as described herein should be able to support loads of about two thousand (2,000) to forty thousand (40,000) lbs. at heights of between about thirty (30) to two hundred fifty (250) ft. while withstanding basic wind speeds of up to about one hundred twenty (120) miles per hour or a combined environmental load of wind at about sixty (60) miles per hour and a layer of radial ice of about ½ in. thick surrounding the support structure 100. The support structure 100 has adequate independent strength and stability to support its telecommunications arrays while also combining with the existing pole 20 via the load transfer plates 310 to provide superior strength and stability to the combined structure as a whole.
While this invention had been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the preferred embodiments of the invention as set forth herein, are intended to be illustrative, not limiting. Various changes may be made without departing from the true spirit and full scope of the invention as set forth herein and defined in the claims.
Claims
1. A support structure for use with an existing single pole tower, said single pole tower comprising a pole anchored to an existing first foundation and supporting a first load, said structure comprising
- a plurality of sleeves, each said sleeve comprising a plurality of polygonal sections, said sections being joined such that said plurality of sleeves surrounds said pole, and
- a first one of said plurality of sleeves being anchored to a second foundation.
2. The support structure of claim 1, wherein said existing tower includes a first base plate anchoring said tower to said first foundation, said first one of said plurality of sleeves comprising a second base plate overlying said first base plate and extending over said second foundation, said second base plate being anchored to said second foundation.
3. The support structure of claim 1, wherein said second foundation comprises a new foundation that surrounds the said existing foundation.
4. The support structure of claim 1, wherein said sleeves comprise a bent structural plate.
5. The support structure of claim 1, wherein each of said plurality of sleeves comprises at least a first section and at least a second section, each section comprising a plurality of polygonal vertical side.
6. The support structure of claim 5, wherein each of said plurality of sleeves comprises at least twelve said polygonal vertical sides.
7. The structural support of claim 5, wherein each of said polygonal sections comprise a first edge and a second edge, said first edge comprising a first bent vertical flange and said second edge comprising a second bent vertical flange.
8. The support structure of claim 7, wherein at least one of said plurality of sleeves comprises a plurality of load transfer plates associated therewith for stabilizing the loaded tower.
9. The support structure of claim 8, wherein each of said plurality of load transfer plates comprise a load bearing plate disposed adjacent to said pole and further comprising a plurality of bolts extending through said sleeves and bearing on said plate for distributing load on said tower.
10. The support structure of claim 8, wherein said plurality of load transfer plates comprise radial spacing around a vertical axis of said sleeves.
11. A support structure for use with an existing single pole tower, said tower comprising a pole anchored to a foundation and supporting a first load, said support structure comprising,
- a first sleeve anchored to a second foundation, and
- a second sleeve fixedly attached to said first sleeve,
- wherein said first and second sleeves surround said pole and are associated with load transfer plates disposed between the pole and the sleeves for stabilizing the loaded tower.
12. The support structure of claim 11, wherein said first and second sleeves are fixedly attached by a number of joinder sleeves.
13. The support structure of claim 11, further comprising a second load fixedly attached to any of said sleeves.
14. A support structure for use with an existing single pole tower, said tower comprising a pole anchored to a foundation, said support structure comprising,
- at least one sleeve surrounding said pole, and
- a load transfer plate disposed between said sleeve and said pole.
15. A method for supporting additional loads on a single pole tower, wherein said single pole tower comprises a pole anchored to an existing first foundation and supporting a first load, said method comprising the steps of:
- surrounding the first foundation with a second foundation,
- positioning one or more sleeves around said pole,
- anchoring said one or more sleeve to said second foundation, and
- supporting said additional load on said one or more sleeves.
16. The method of claim 15, further including disposing load transfer plates between the pole and the sleeves and torquing load transfer bolts against the load transfer plates until the load transfer plates are snugly positioned against the existing tower.
17. The method of claim 16, wherein said load transfer bolts are tightened against the load transfer plates to stabilize the loaded tower.
18. The method of claim 17, further comprising the step of attaching said first and said second sleeve by one or more joinder sleeves.
19. The method of claim 15, wherein said sleeves comprise a bent structural plate.
Type: Application
Filed: Dec 7, 2004
Publication Date: Aug 25, 2005
Inventor: David Cash (Norcross, VA)
Application Number: 11/005,889