WO2000046452A1

WO2000046452A1 - Support structure for elevating and supporting monopoles and associated equipment

Info

Publication number: WO2000046452A1
Application number: PCT/US2000/002894
Authority: WO
Inventors: Steven B. Smith; C. William Savitz; Gerald W. Newman
Original assignee: Northern Technologies Inc
Current assignee: Northern Technologies Inc
Priority date: 1999-02-05
Filing date: 2000-02-04
Publication date: 2000-08-10
Anticipated expiration: 2001-08-05
Also published as: AU3589000A; WO2000046452A9

Abstract

The present invention relates to an elevated support structure (30) designed primarily to support a communications antenna (32) mounted atop a monopole (34) and all accompanying equipment. The support structure (30) comprises a mounting ring (38) having six base legs (40) extending therefrom, equidistant from one another. Each base leg (40) has an anchoring foot (44) attached at its end that is anchored to a perimeter foundation (46). The perimeter foundation (46) is comprised of either a concrete pier or a unique combination of an earth/rock anchor (50, 55) and a reinforced concrete footing (52). Decking (82) may be mounted to, and span between, the base legs (40) of the support (30) to support cabinets, telco cabinets, and shelters (36) for housing accompanying equipment.

Description

SUPPORT STRUCTURE FOR ELEVATING AND SUPPORTING MONOPOLES AND ASSOCIATED EQUIPMENT

FIELD OF THE INVENTION

The present invention relates m general to telecommunications towers and in particular to a support structure for elevating, mounting and supporting large antenna poles used for the transmission of radio, television, and telecommunication signals and all equipment associated therewith.

BACKGROUND OF THE INVENTION

Over the past several years, the number of cellular and digital telephone users has dramatically increased. Most users desire a large coverage area and the ability to use their cellular or digital telephones when traveling, regardless of their location. To service the increasing number of wireless telecommunications customers and provide expanded areas of service, providers must install a large number of new telecommunications towers. To provide a large area of service, towers are required m both urban and rural areas. In the more densely populated areas, towers are often needed one to five miles apart from one another . Most telecommunications towers are comprised of large monopoles having communications antennas attached atop the monopoles for receiving and transmitting telecommunications signals. Monopoles generally range m height from 80 and 220 feet and are anchored at their base to supporting foundations to prevent the overturning of the towers.

New construction of telecommunications towers has consistently been a problem. Most telecommunications towers are anchored to massive upright cylindrical pier foundations or mat foundations. Conventional foundations, such as pier and mat foundations, are typically comprised of a large mass of reinforced concrete and are sunk deep into the earth to prevent the overturning of the monopoles Because conventional cylindrical pier foundations and mat foundations are sunk into the earth, extensive site excavation and preparation is required prior to the pouring of these large foundations. With the large amounts of concrete required for each foundation, much of the installation time is attributed to site preparation and concrete curing. Site excavation and concrete curing alore can take up to seven to ten days. Because most sites are required to be erected within a very demanding time frame, the amount of time associated with site excavation and curing is the largest problem with the construction of new telecommunications towers. In addition, a typical telecommunications tower may have several appurtenances, such as equipment cabinets, electrical cabinets and shelters, which require additional foundations. Thus, the installation of each appurtenances increases the cost of installation and development time. Often times, when providers co-locate on one tower, the foundations for the appurtenances are poured after the telecommunications tower has been installed thus, requiring additional site and foundational work apart from the work done during construction.

In the past, temporary towers have been constructed to meet demanding time constraints. These temporary towers, however, have limitations on the amount of overturning moment they can accommodate, and therefore, do not properly support larger towers and do not offer a permanent solution to the problems with new installations.

Accordingly, the support structure of the present invention provides a permanent solution for addressing the problems associated with new construction, such as material costs, installation time and the additional foundational work required for appurtenances. The present invention provides for a support structure that reduces the amount of site preparation and materials required for new construction and allows for the appurtenances to use the same foundation and supporting structure as the monopole . Thus, the present invention allows for the subsequent installation of appurtenances and for the reconfiguration of appurtenances without the need for additional site or foundational work.

SUMMARY OF THE INVENTION

The support structure of the present invention is comprised of a steel support structure having a mounting ring at its center for anchoring the monopole and six base legs extending radially from the mounting ring Each base leg is then anchored at its end to a perimeter foundation. Thus, the load of the monopole and support structure is distributed to and supported by the perimeter foundations Distributing the load toward the perimeter of the support structure provides for a substantially uniform resisting moment against the wind, seismic and other laterally applied forces.

Additionally, spreading the load of the tower to its perimeter reduces the amount of materials required by the foundation and therefore, makes it easier to assemble and/or install relative to conventional pier and mat foundations. The costs, transportation, resources and time required for installation of the tower are also minimized Furthermore, having discrete foundational elements eliminates the requirement for slab excavation and allows installation of the support structure on sloped sites or sites that are not easily excavated. Additionally, any inaccuracies m the foundation construction may be overcome by utilizing conventional leveling devices located at the anchored end of each base leg. The unique hexagonal configuration of the support structure also allows for the installation of guy wires to support the monopole from each of the six base legs. The base leg sections are constructed from a number of linear sections that, ir one embodiment, are tapered I-beams. These sections can -oe separately transported and assembled with commonly available tools.

The support structure of the present invention can be used not only to support monopoles for telecommunications antennas but also for other commercially available monopoles used to support overhead lighting, flag poles, utility poles, power line structures and supports for extensive vertical sections of fencing or netting. This invention also allows for the installation of associated equipment on the support structure by spanning decking between the base legs of the support structure. The additional weight of the installed equipment on the support structure serves to increase the resistive moment of the structure. Further, the installation of tne equipment on the support structure elevates the equipment above ground, thus reducing or eliminating potential damage from contaminates such as snow, water and animals typically associated with on-ground installations. This equipment installation feature also provides excellent site electrical grounding for the equipment .

Accordingly, the primary object of the present invention is to provide a support structure for a telecommunications monopole and all related equipment that requires minimal site preparation, can be quickly installed, and uses minimal foundational materials.

Another object of the present invention is to provide a support structure that distributes load so as to minimize the overturning moment of the tower.

Yet another object of the present invention is to provide a support structure that can be installed within a demanding time frame and that allows for the monopole and all appurtenances to be supported by one single support structure .

Still another object of the present invention is to provide a support structure that provides an elevated platform for supporting all accompanying equipment associated with telecommunications antennas and that provides for the ease and flexibility to reconfigure and add appurtenances without additional site or foundational work.

A further object of the present invention is to provide a support structure that can be used with other commercial monopole applications or that can be used solely as a foundational platform for supporting equipment m a variety of commercial applications.

In accordance with these and other objects, the present invention provides an elevated support structure designed primarily to support a communications antenna mounted atop a monopole and all accompanying equipment. The support structure comprises a mounting ring having six base legs extending therefrom and positioned equidistant to one another. Each base leg has an anchoring foot or bolt cage attached at its end that is anchored to a perimeter foundation. In one embodiment, each perimeter foundation is a discrete foundational element that is comprised of either a concrete pier or a unique combination of an earth/rock anchor and a reinforced concrete footing. Decking may be mounted to, and span between, the base legs of the support structure to support cabinets, telco cabinets and shelters for housing accompanying equipment .

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the support structure of the present invention with a monopole tower attached thereto. FIG. 2 is a perspective view of the installation of the support structure of the present invention. FIG. 3 is a perspective view of the support structure of the present invention. FIG. 4 is a plan view of the support structure of the present invention and its perimeter foundation.

FIG. 5 is a side view of the perimeter foundation illustrated m FIG. 4. FIG. 6 is a sectional side view of one base leg of the support structure of the present invention, as it appears anchored to a perimeter foundation.

FIG. 7 is a plan view of the mounting ring illustrated in FIG. 6 FIG. 8 is a sectional side view of an inverted base leg of the support structure of the present invention, as it appears anchored to an elevated perimeter foundation.

FIG. 9 is a cross-section view of the base leg support illustrated in FIG. 8 taken along line 9—9. FIG. 10 is a sectional view of a perimeter foundation of the present invention using both an earth anchor and a reinforced concrete footing.

FIG. 11a is a perspective view of earth anchors used in connection with the present invention. FIG. lib is a perspective view of a rock anchor used in connection with the present invention.

FIG. 12 is a perspective view of two earth anchors illustrating the interconnection of the two anchors by coupling bolts. FIG. 13 is a perspective view of an earth anchor having its extension end incorporated into a rebar cage of a concrete footing.

FIG. 14 is a plan view of a rebar cage of the concrete footing of the present invention.

FIG. 15 is a plan view of a base leg of the present invention anchored to a perimeter concrete footing.

FIG. 16 is a perspective view of the support structure with an electrical grounding system attached thereto. FIG. 17 is a plan view of a support structure of the present invention having decking attached thereto.

FIG. 18 is a plan view of a support structure of the present invention having a shelter for housing equipment . FIG. 19 is a side perspective view of an anchor foot of the present invention having a fence post attachment extending therefrom.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

As best seen m FIGS. 1 and 18, the present invention relates to a support structure 30 designed primarily to support a communications antenna 32 mounted atop a monopole 34 and all accompanying equipment. The present invention can, however, be used to support monopoles 34 for other commercial uses or can simply act as an elevated support platform for maintaining commercial equipment, storage sheds 36, and the like.

As illustrated in FIGS. 1 through 3, the support structure 30 of the present invention is a steel structure comprising a centrally located mounting ring 38 having six base legs 40 extending radially therefrom. Each base leg 40 extends from the mounting ring 38 such that each base leg 40 is positioned equidistant from one another and thus creates symmetry about the center of the support structure 30. As illustrated by FIGS. 3 and 4, all six base legs 40 are equal in length and size to one another and are generally formed of tapered I-beams, having horizontally extending flanges 41 and 42 on the upper and lower surfaces of each base leg 40. As shown in FIG. 6, each base leg 40 has a anchoring foot 44 or bolt cage that is attached at the end of the base leg 40 opposing the mounting ring 38. Each anchoring foot 44 is then anchored to a perimeter foundation 46 positioned below the anchoring foot 44. As discussed m more detail below, each perimeter foundation 46 can be comprised of either a reinforced concrete pier or pilaster 48, as seen m FIGS. 5, 6 and 8, or comprised of a unique combination of an earth/rock anchor 50, 55 and a reinforced concrete footing 52, as illustrated by FIGS. 10 through 14. As illustrated by FIGS. 2, 3, 4, 6 and 7, the mounting ring 38 of the present invention functions as a hub or pedestal for the support structure 30, having the monopole 34 anchored to the mounting ring 38 at its upper surface The mounting ring 38 is comprised at its center of a generally hollow cylindrical extra strong pipe 54 having an upper 56 and lower 58 generally circular or hexagonal shaped flange extending from the pipe 54. As illustrated by FIGS. 6 and 8, the monopole 34, or mast, is rigidly affixed to the upper flange 56 of the mounting ring 38 with bolts and washers 60.

Extending vertically between the upper and lower flanges 56 and 58 of the mounting ring 38 are six equally spaced leg connectors 62, illustrated m FIGS. 3 and 7, extending radially from the center pipe 54 of the mounting ring 38. As shown m FIG. 7, each leg connector 62 terminates with a connection plate 64 just beyond the perimeter of the upper and lower flanges 56 and 58. The base legs 40 are connected to the connection plates 64 of the leg connectors 62 with washers and bolts 60, as illustrated in FIGS. 6 and 8.

Although the mounting ring 38 of the present invention is illustrated m FIG. 2 as having a circular configuration and is illustrated m FIG. 3 as having a hexagonal configuration, the mounting ring 38 of the present invention can be comprised of any configuration adequately designed to act as a pedestal for a monopole 34 and equally distribute the bearing load of the monopole 34 to base legs 40 attached to and extending from the mounting ring 38. When the support structure 30 is use only as a platform, the mounting ring 38 may be redesigned to provide for only the connection of the base legs 40 to the mounting ring 38 and not provide for a monopole 34 support.

As discussed previously, the base legs 40 attach to the connection plates 64 of the leg connectors 62 of the mounting ring 38 with washers and bolts 60. As shown m

FIGS. 2 and 3, the base legs 40 are generally comprised of tapered I-beams. Thus, the base legs 40 have upper and lower flange members 41 and 42 and a web member 66 extending between the flanges 41 and 42, which, as shown m FIGS. 6 and 8, varies m height across of the length of the I-beam. The end of each base leg 40 having the tall web member 66 is attached to the mounting ring 38 and thus, the end of the base leg 40 having the short web member 66 is attached to the anchoring foot 44 or bolt cage, as the case may be .

To enable the base legs 40 of the support structure 30 to support items m addition to the monopole 34, the upper flanges 41 of the base legs 40 must create a flat, horizontal surface relative to one another, as illustrated m FIGS. 2 and 6. The base legs 40 can be inverted, as shown m FIG. 8, to accommodate more challenging grades; however, when the legs 40 are inverted, the upper surface of the support structure 30 cannot alone provide horizontal support for housing equipment. Additionally, while the base legs 40 are designed as tapered I-beams, other base leg 40 or linear designs may be employed that provide for the same functional characteristics as the base legs 40 of the present invention.

FIG. 4 illustrates each base leg 40 attached to an anchoring foot 44 at its end. As shown m FIGS. 6 and 8, each base leg 40 is attached to an anchoring foot 44 with washers and bolts 60. The anchoring feet 44 are then equipped with anchor bolts 68 for anchoring the base legs 40 to a perimeter foundation or foundational element 46. Alternatively, bolt cages (not shown) could be welded to the end of each base legs 40 to anchor the legs to the foundation.

While a variety of differently configured foundational elements 46 may be used to support the base legs 40 of the present invention, a foundation using six separate and discrete foundational elements 46, as shown in by FIGS. 17 and 18, reduces the amount of required material and decreases the installation time of a new telecommunications tower. Each discrete foundational element 46 may be comprised of either a concrete pier or a unique combination of an earth/rock anchor 50,55 and a reinforced concrete footing 52. In one embodiment of the invention, conventional perimeter foundations, such as steel reinforced pier, pilaster and caisson concrete foundations may be utilized for the foundational elements 46. Examples of these foundational elements 46 are found in FIGS. 4, 5, 6 and 8. In another embodiment, a unique foundational design combines the use of an earth or rock anchor 50 and 55 and a reinforced concrete footing 52 to further reduce the amount of foundational materials and time required for installation of the telecommunications tower.

In this embodiment, earth anchors 50, such as the type HS extendable foundation earth anchors sold by A.B. Chance Company and illustrated m FIGS. 11a and 12, are used m conjunction with reinforced concrete footings 52 to form the discrete foundational elements 46. The AB Chance earth anchors are high-strength foundation anchors having galvanized multi-helix lead sections comprised of 3 -inch extra-heavy pipe.

In the present invention, the earth anchors 50 are placed into the ground to a predetermined torque value through the use of an auger. As necessary to achieve the desired torque value, extensions may be placed on the earth anchors 50, as shown m FIG. 12. Each end of the earth anchor 50 is adapted to connect to the opposing end of a second earth anchor by bolted couplings 51. Once the earth anchors 50 are m place, the concrete footings 52 are then formed around the upper end of the earth anchor 50, as illustrated m FIG. 15. A reinforced steel matrix or rebar cage 70 is formed within each footing 52. As shown m FIG. 14, both the upper end of the earth anchor 50 and the anchor bolt 68 of the support structure 30 are located within and connected to the rebar cage 70 When using an earth anchor 50 designed to accommodate extensions having bolted couplings 51, the rebar 72 comprising the rebar cage 70 may be threaded through the horizontally aligned holes m the earth anchor 50, as illustrated m FIG. 13. Unlike the present invention, a termination adapter is typically coupled with the end of earth anchor 50 and the termination adapter may then be embedded into a concrete cap.

Once the rebar cage 70 is fabricated, concrete is then poured to form the footing 52 and allowed to cure. The amount of concrete is greatly reduced with the use of the earth anchors 50. In most instances, only approximately 1 yd of concrete is required to fill each of the six discrete foundational elements 46. Thus, the concrete for each perimeter foundation 46 can be mixed on site, if necessary Alternatively, the concrete footing 52 for each perimeter foundation 46 may be formed from pre-cast concrete sections and installed at the site. In situations where the site requires the use of rock anchors 55 rather than earth anchors 50, rock anchors 55, such as those sold by Williams Form Engineering Corporation and illustrated m FIG. lib, may be used m conjunction with the concrete footings 52 just as the earth anchors 50. Like the earth anchor 50, the upper end of the rock anchor 55 may be located and connected to a rebar cage 70 m the concrete footing 52. Typically, the rock anchors 55 are grout bonded to the underlying bedrock and are equipped with a fitting 53 on the end of the rock anchor 55 for connecting to the rebar cage 70 of the concrete footing 52 Similar to the extension end of the AB Chance earth anchor 50, the rock anchors 55 may be equipped with specially designed fittings having holes for receiving the rebar 72 comprising the rebar cage 70 m the footings 52.

When the bearing, shear and axial loads allow, the anchoring feet 44 may be attached directly to the earth anchors 50 or rock anchors 55 without the need for the reinforced concrete footings 52, as shown by FIG. 16. Additionally, high-strength foundation earth anchors 50, other than the A.B. Chance earth anchors, may be used m connection with the present invention. If earth anchors 50 or rock anchors 55 are utilized that do not provide holes that may be used to receive rebar 72, the end of the earth anchor 50 or rock anchor 55 may be tied into a rebar cage 70 m a manner similar to the anchor bolt 68. Alternatively, an adapter or fitting may be specially designed with holes to receive rebar 72 and may be coupled with the earth anchor 50 or rock anchor 55.

As illustrated by FIG. 16, the present invention may be provided with a unique electrical grounding system that obviates the need for separate ground rings when used m connection with the foundations utilizing earth or rock anchors. Additionally, the present invention reduces the number of required grounding rings when used with conventional pier, pilaster or caisson reinforced concrete foundations .

The design of the support structure 30 provides an inherent electrical advantage over conventional towers in the fact that the support structure 30 is a large metallic surfaces that can be bonded directly, m-lme, to the earth through the use of grounding rings or earth/rock anchors 50,55. As shown m FIG. 16, copper wires 74 extending from the monopole 34 are welded to each base leg 40 of the support structure 30. Then, as further illustrated by FIG. 16, when used m connection with earth 50 and rock anchors 55, an additional set of copper wires 74 are positioned between each base leg 40 and the underlying earth or rock anchor 50 and 55. Welding is again used to secure the copper wires 74 against the base legs 40 and earth or rock anchors 50 and 55. In a similar manner, any equipment mounted on the support structure 30 can be grounded with copper wire 74 extending to the base legs 40 of the support structure 30.

When a concrete footing 52 is utilized with the perimeter foundation 46, the copper wire 74 can extend through the concrete footing 52 and be connected below the footing 52 to the anchor 50 as illustrated FIG 14 Alternately, the wire 74 may be directed around the concrete footing 52 and connected to the earth or rock anchor 50 and 55 just below the footing 52. When desired to run the wire 74 through the footing 52, the footing 52 is designed with a hollow tube or pipe 76 extending through the footing 52 for receiving the copper wire 74. Alternatively, when concrete piers, pilaster or caisson foundations are utilized grounding rings are attached directly to the support structure 30 to ground the structure .

When equipment, cabinets and/or shelters 36 are desired near the support structure 30, angular brackets 78 may be placed between the base legs 40 to provide a level platform for housing the desired equipment, as illustrated m FIG. 9. Decking 82 can then be fastened to the base legs 40, as shown by FIGS. 17 and 18. As shown in FIGS. 8 and 9, the angular brackets 78 are bolted to knife plates 80 that are welded to the web of the base legs 40 In one embodiment, the decking 82 is standard galvanized steel bar grating and is attached to the upper flanges 41 of the base legs 40 by steel bar grating clamps (not shown) . Other types of decking 82 such as an aluminum, fiber glass or like decking material may used and affixed to the base legs 40 and angular brackets 78 in a manner appropriate for the selected type of decking.

Where the shelters 36 and equipment are large enough to span across two base legs 40, the decking 82 and angular brackets 78 may be unnecessary unless an elevated platform is required for easy access to the equipment. FIG. 18 illustrates two base legs 40 supporting a shelter without the necessity of underlying decking 82. While angular brackets 78 are shown, they may be unnecessary depending upon the strength and size of the shelter. The base legs 40 alone are capable of supporting the equipment and equipment shelters.

Additionally, the design of the present structure may eliminate the need for ice bridges. Because the support structure 30 is elevated, telecommunications cables can exit the monopole 34 through the bottom of the mounting ring 38, run along the lower flange 42 of the base legs 40 and come up underneath any equipment sheds 36. By running the cables along the underside of the structure, the support structure 30 itself acts to shield the cables from ice. Similarly, should the monopole 34 not allow the cable to exit below the mounting ring 38, the cable could be positioned along the support structure 30 such that the decking 82 or upper flange 41 of the base leg 40 could act to shield the cable from ice, and thereby reduce the need for ice bridges .

Lastly, if desired, the anchoring feet 44 of the present invention may be equipped with fence post attachments 84, as illustrated FIG. 19. These attachments 84 allow fencing to be placed around the perimeter of the tower. The anchoring feet 44 are designed with hollow elongated tubes 86 attached thereto for receiving an extension bar 88 with a fence post attachment 84 at its end.

One of ordinary skill m the art understands that the structural components of each support structure of the present invention will vary depending upon the design parameters of each structure . Support structures encountering different bearing, shear and axial loads will require different structural components, and thus, no two support structures of the present invention will likely possess all of the same structural characteristics unless the design parameters of the two support structures are virtually identical.

While the present invention has been disclosed in reference to the disclosed embodiments, other arrangements will be apparent to those of ordinary skill in the art and are to be considered within the spirit and scope of the present invention. The invention is, therefore, to be limited only as indicated by the scope of the claims that follow and their equivalents.

Claims

CLAIMSWe claim:

1. An elevated steel support structure for supporting and resisting large bearing, shear and axial loads, said support structure comprising: a mounting ring; a plurality of base legs attached to and extending radially from said mounting ring, said plurality of base legs each having a first and second end, said first end being attached to said mounting ring; a plurality of perimeter foundations, wherein the second end of each said base leg is anchored to at least one said perimeter foundation such that all the bearing load of said support structure is spread to the perimeter of the support structure.

2. An elevated support structure as recited claim 1, wherein said mounting ring has an upper supporting flange .

3. An elevated support structure as recited claim 1, wherein said perimeter foundations are reinforced concrete piers .

4. An elevated support structure as recited claim 1, wherein said support structure has six base legs

5. An elevated support structure as recited m claim 4, wherein said support structure has six perimeter foundations .

6. An elevated support structure as recited in claim 1, further comprising decking attached to and expanding between said base legs.

7. An elevated support structure as recited in claim 1, wherein said perimeter foundation is a combination of an earth anchor or rock anchor with a reinforced concrete footing .

8. An elevated support structure as recited m claim 7, wherein said base leg has an anchor bolt for attaching said base leg to said perimeter foundation and wherein said concrete footing of said perimeter foundation has a rebar cage contained therein that embraces both the anchor bolt of said anchor bolt of said base leg and said earth or rock anchor .

9. An elevated support structure as recited in claim 8, wherein one end of said earth or rock anchor has holes running horizontally therethrough for receiving a rebar of the rebar cage in said concrete footing.

10. An elevated support structure as recited in claim 1, wherein said base legs are equidistant from one another.

11. A steel support structure for supporting a mast, said steel support structure comprising: a mounting ring having an upper flange for supporting and connecting the base of the mast; six base legs extending radially from said mounting ring, said six base legs each having a first end and a second end, said first end being attached to said mounting ring ; six perimeter foundations, each perimeter foundation positioned directly under and anchored to the second end of one of said six base legs, each said perimeter foundation being comprised of an earth or rock anchor and a reinforced concrete footing.