WO2003076737A1

WO2003076737A1 - Method and arrangement for utility pole reinforcement

Info

Publication number: WO2003076737A1
Application number: PCT/US2003/007088
Authority: WO
Inventors: Ray Ullrich; James Hobbs; James Harpole
Original assignee: Commstructures, Inc.
Priority date: 2002-03-07
Filing date: 2003-03-07
Publication date: 2003-09-18
Also published as: AU2003252829A1

Abstract

Method and arrangement for reinforcing an utility pole (3) including a plurality of anchorages (28, 29), each of which are locatable at a different vertical position on the utility pole (3) and having a tension member (30) configured to be coupled between at least a pair of said anchorages (28, 29) for increasing the load capacity of the receiving utility pole (3) when thereby fortified. Exemplarily, the utility pole (3) is configured to receive above-ground appurtenances. In a complimentary embodiment, the arrangement further includes a compression member (36), which may take the same form as the tension member (30), but with oppositely acting forces imposed therein.

Description

METHOD AND ARRANGEMENT FOR UTILITY POLE REINFORCEMENT

FIELD OF THE INVENTION:

The present invention relates to elongate support elements; and more particularly, to methods and arrangements for fortifying aerial and utility poles.

BACKGROUND OF THE INNENTION:

Elongate, upright poles are utilized in many industries for many applications. In the most simple of configurations, such poles may serve as flag poles or sailing masts. In more complex arrangements, upright poles are used in the utility industries for elevating utility lines, as well as positioning certain devices above ground level. Regarding such aerially located devices, one example is the elevation of outdoor lighting such as for street lamps, but an increasingly important utilization of such utility poles is the elevation of antennas and receivers for cellular telephone and similar wireless communication services.

The presence of such utility poles is generally seen as detrimental to the landscape. Therefore, the number of utility poles is desirably minimized in most locations. As a result, it has become increasingly important to maximize the utilization of any given pole once erected. Still further, the proliferation of wireless communication providers has increased the need for aerial antennas placements.

Typically, the utility poles are owned and maintained by one entity, and space is leased thereupon to the communication companies for their equipment. As a result, these utility poles owners and operators are constantly striving to ever increase the capacity of their existing facilities. Each pole, however, has a maximum loading capacity for which it was originally designed. This original design capacity is oftentimes quickly exceeded and therefore reinforcement of the pole to increase its carrying capacity is desired. Traditional methods for providing reinforcement have included the welding of angle along the exterior surface of the pole in those regions requiring reinforcement. This is a particularly disfavored solution not only because it is unsightly, but because extremely long beads of weld are generally required which are not only time-consuming and labor-intensive to apply, but can also be structurally degrading to the pole, itself. Still further, a common construction of such poles is of galvanized metal. Therefore, any welding imposed thereupon compromises the galvanization protection. As a result, "cold galvanization" is typically required in an effort to re-establish the corrosion-resistant features of the pole after welding thereupon has been completed.

In general, the utilization of welding is undesirable in aerial environments. In a first instance, the related personnel cost for elevated, above-ground welding is high, and there is often a scarcity of qualified personnel. Further still, the extreme temperature conditions imposed upon the utility pole during a welding process can damage associated structures. < For example, coaxial cable is often housed within the core of the utility pole. When welding is affected upon the body of the pole, the associated heat can not only damage such cabling, but has also been known to ignite insulation layers provided upon such cable resulting in the complete loss of the facility due to fire.

Another problem associated with existing reinforcement strategies is that installed communication units positioned upon the utility pole must be disturbed; that is, service interruption may be necessary to those companies already having antennas and receivers on the pole to accommodate the reinforcement process. As a result, added costs and complications must be dealt with to perform such reinforcement processes, including performing such updates or remedial measures at night when service to wireless customers is less likely to be interrupted. Still another problem has been encountered when the cabling from the elevated antennas and receivers down to the ground facilities is positioned exteriorly upon the pole, as opposed to interiorly within the pole's core. Some reinforcement solutions require components to completely encircle the pole. If that is the case, exterior cabling must be either removed, or at least temporarily positioned at a sufficient distance away from the pole to give operating space for installation of the reinforcement components. This requirement often imposes logistical problems, and almost always increases the time and cost associated with the remedial measures.

Responsive to these needs for increased aerial capacity, particularly in the wireless communication industries, and the problems associated with traditional utility pole reinforcement, the present invention(s) has been developed.

SUMMARY OF THE INNENTION:

The present invention may take the form of either, or both of a method and

an-angement for reinforcing an utility pole including a plurality of anchorages, each of

which are locatable at a different vertical position on the utility pole and having a tension

member configured to be coupled between at least a pair of said anchorages for increasing

the load capacity of the receiving utility pole when thereby fortified. Exemplarily, the

utility pole is configured to receive above-ground appurtenances. In a complimentary

embodiment, the arrangement further includes a compression member, which may take

the same form as the tension member, but with oppositely acting forces imposed therein. BRIEF DESCRIPTION OF THE DRAWINGS:

Fig. 1 is a perspective view of an exemplary utility pole arrangement;

Fig. 2 is a perspective view of a footing of the utility pole arrangement;

Fig. 3 is a schematic view of the exemplary utility pole arrangement showing regions of stress induced by load-induced bending thereof;

Fig. 4 is a top plan view of a flange in Fig. 3 which may be located at the footing portion of the pole;

Figs. 5-9 are perspective views of utility pole mounted reinforcement areangements;

Fig. 10 is a top plan view of an exemplary connective flange shown in Fig. 11;

Fig. 11 is a schematic view of an exemplary utility pole arrangement showing details of variously configured anchorages;

Figs. 12-16 variously show exemplary reinforcement arrangements, as well as constituent components thereof;

Figs. 17-24 variously show collar-embodiments of the present invention, the eccentricity depicted in Figs 17 and 18 are as well descriptive of embodiments employing independent anchorages; and

Figs. 25-31 variously illustrate upper and lower anchor brackets, as well as guide arrangements.

DESCRIPTION OF THE INNENTION(S):

Fig. 1 exemplary demonstrates one type of aerial or utility pole 3 construction commonly utilized for elevating appurtenances 7 such as wireless communication antennas and receivers. This design is commonly referred to as a step, tapered pipe pole. The version shown in Fig. 1 is made up of a series of stacked, substantially cylindrical joints 15; each joint having a reduced diameter with respect to those below. The utility pole 3 is shown to include climbing pegs 21 for service personnel, as well as a safety cable 24 to which such personnel are attached during service operations. A typical base 12 and concrete footing or pad 6 for such a pole 3 is shown in Fig. 2.

Figs. 3 and 4 show a schematic elevational view and horizontal cross-sectional view, respectively, of an aerial or utility pole 3 such as that depicted in Figs. 1 and 2. The cross- hatched regions of Fig. 3 illustrate high stress zones (normally flexural stress) requiring reinforcement. The stress in these zones is primarily attributable to bending forces induced by the upper loads on the pole 3. Though weight is a component that must be considered, the primary force-factor results from wind resistance, particularly from the implications of increased wind resistance caused by additional features, appurtenances and accessories, such as wireless antennas and receivers 7, added at the upper regions of the pole. These high stress zones, typically identified through computer-aided analysis, are the regions which must be reinforced in order to provide additional carrying capacity to an existing pole structure. In this analysis, there may be different limiting factors. One factor may be the construction of the pole 3 itself, but of equal significance are the support capabilities of the pole's footing 6. Regardless of how strong the pole 3 can be made, the capacity of the footing 6 may not be exceeded.

Figs. 5 - 16 disclose one exemplary reinforcement scheme configured according to the present invention and installed on a twelve-sided, polygon-shaped pole 3. Four primary components of each reinforcement arrangement are shown in Figs. 5 and 6; those components including upper anchor brackets 28, lower anchor brackets 29, and tension rods 30 and guides 33 therefore. Fig. 6 demonstrates a top-to-bottom communication cables 8 secured to an exterior surface 9, front face of the utility pole 3. In the embodiment shown, this communication cable 8 is secured to a front face of the pole 3 located interstitially between two faces upon which two reinforcement arrangements 25 are each positioned.

Referring to Figs. 7 and 8, perspective views are provided of the upper 28 and lower 29 anchor brackets or assemblies that are each configured in substantially the same way. Namely, various bracing members or elements 50 are provided about an anchor plate 53 through which the tension rod 30 projects. A nut 55 is then secured upon end threads of the rod 30 and secured against an exterior surface of the anchor plate 53. By further tightening one or two nuts 55 on opposite ends of the rod 30, a prescribed pre-tension is applied across the tension member 30. This pre-tension is important because it tends to eliminate "slop" in the pole 3 and the reinforcement arrangement 25.

From an engineering perspective, the combination of a pair of anchorages 28, 29 and an interconnected tension member or rod 30 constitute a reinforcement arrangement or element 25 that contributes resistance to bending of an erect pole 3. As the top of the pole 3 bends in one particular direction, typically under wind load, the rod(s) 30 on the opposite (upwind) side of the pole 3 go into increased tension. The rods 30 on the same side of the pole 3 as the direction of bend (down-wind) either go slack, or transition into compression for further reinforcement. In the case that the rods 30 are configured for accepting compression forces, the rod ends must be bi-directionally secured; that is, fixed with respect to the anchor

plate 53.

It has been discovered that for some utility poles 3, especially those that are heavily loaded, the tension rod approach alone will not always provide sufficient fortification. Responsively, a complementary compression member or rod 36 configuration has been developed that would force the rod elements 36 on the compression face of the pole shaft 3 to take-up compressive forces. In order to do this, the anchorage configurations 27 have to be appropriately designed to handle the reversal in the force direction (with respect to tension conditions) and the rods 36 have to be braced against buckling. This results in the end supports 28, 29 being spaced much closer together than for the tension rod designs. However, a much greater composite section capacity is obtained and, hence, a much larger load carrying capacity for such a reinforced pole 3 is achieved. When considering compression members 36, exemplary embodiments require double nuts 55, or suitable equivalents to achieve the compression rod configuration, while only a single nut can be utilized for the tension rod configuration. In practice, it should be understood that if a reinforcement arrangement 25 is configured to act as a compression member 36, by fastening the rod 30 to the upper and lower anchor brackets 28, 29 against both upward and downward translational movement, that same arrangement 25 will act as a tension member 30 when opposite (tensile) stress or force is applied thereto.

The present invention contemplates, among others, systems in which only externally applied high strength tension rods 30 are installed with some amount of pre-stress or pretension load imposed. While rods 30 are applied symmetrically with respect to the pole cross section (typically 6 or 8 rods), only the rods 30 that develop tensile forces are included in the strength equation when designing and tuning the system. It should be appreciated, as otherwise explained herein, that when the pole shaft tube 3 is bent in flexure, there exists a compression face at which the pole 3 tends to shorten under load and a tension face at which the pole 3 tends to stretch or lengthen. Rods on the compression face tend to go slack or buckle so only the rods 30 that carry tension are active. As a result, what can now be considered a composite structural element; that is, the pole shaft 3 and the reinforcement arrangements 25 having active tension rods 30, when taken together, are asymmetric with a center of gravity (CG) of the composite element displaced slightly toward the tension rod face of the pole. The result is an increase in the pole's moment of inertia, I. It is this increase in moment of inertia that allows for more load carrying capacity in the pole shaft 3. Each tension rod can generally be considered a tension element, but when described herein, each tension element can include one or more tension rods.

The actual moment of inertia of an exemplary composite section is influenced by at least: (1) the moment of inertia of the pole shaft, (2) the tension rod area, and (3) the rod's eccentricity; that is, the distance the rod is spaced with respect to the pole shaft. Typically, for any given pole section, the pole shaft moment of inertia is constant, but the tension rod size, and hence, its area, can be varied as can the rod's eccentricity. In the design process, this becomes an interactive exercise that eventually will result in the desired geometry. Therefore, for a given pole shaft section and associated tension rod arrangement (cross- sectional area and eccentricity), the amount of tensile force that a particular rod carries can be computed.

It has been discovered that within the length of a given tension element 30 which is generally taken as being the rod extension between rod termination mounts (RTM) 28, 29, the eccentricity will need to be greatest at the bottom end and least at the top end of the reinforcement arrangement 25. Also, the tension force in the rods 30 is commensurately greatest at the bottom and least at the top. Since the experienced tension force actually varies along the length of the rod 30, the difference in force between the two end points must be taken-up.

In one embodiment, rod positioners can comprise U-bolt clamps 60 for fixing the rod to the pole as shown in Fig. 32. This attachment transfers a longitudinal force (the difference in the rod tensions) and a lateral force (due to the curved shape of the bent pole shaft). Differently configured anchor brackets and rod positioners can be utilized; exemplary configurations include welded T-sections, U-bolt on I-sections, and U-bolt on L-sections 62 as shown in Fig. 33. In Figs. 32 and 33, fastening arrangements are shown to include hollo- type bolts that are particularly advantageous in this setting because of their self-securing capacities.

In practice, welded T-sections function particularly well from a structural perspective, but they present scheduling problems with respect to fabrication. For this reason, the U-bolt configurations are more typically utilized in implementations of the present invention.

In order to maintain the integrity of the rod 30, 36 , its position with respect to the pole 3 must be substantially fixed. As the pole bends, without the guides 33, 39 illustrated in Fig. 9, the rods' orientation with respect to the pole 3 can change. Therefore, guides 33, 39, which will be described in greater detail hereinbelow, are preferably provided at intervals along the length of each rod 30, 36 which laterally secure the rod with respect to the pole3 , but also allows free longitudinal movement of the rod 30, 36 within the guide 33, 39. It should be appreciated that the guide's 33, 39 character as between tension and compression is determined by what kind of force (tension or compression) the associated rod 30, 36 is carrying.

Fig. 11 provides an elevational, schematic representation of a multi-section 15, stacked, 12-sided polygon-shaped utility pole 3. Each section 15 tapers from its lower to upper end, and each lower end is sized and configured to fit over the top end of the section located immediately therebelow. Because of this tapered configuration and relative sizing, the multiple sections 15 may be stacked to form the elongate utility pole 3. This configuration establishes overlap regions 18 between the sections 15 characterized as overlapping joints in Fig. 11. In the blow-up details at the right-hand side of Fig. 11, three different anchor brackets are illustrated. Primarily, it is demonstrated that one or more tension rods may be incorporated into a reinforcement arrangement. In the upper detail of Fig. 11, an anchorage 27 is shown having rods 30, 36 extending in just one direction. In each of the lower details of Fig. 11, an anchorage 27 is shown having rods 30, 36 extending in both directions. It is based on such double-connections to the anchorages that composite forces are imposed for transfer to the carrying pole 3.

Fig. 10 shows a downwardly directed view of a securement flange 13 of the utility pole 3.

The reinforcement arrangements 25 shown perspectively in Figs. 5 and 6 are depicted in greater detail in Figs. 12 - 16. Figure 12 provides an elevational view showing three individual reinforcement arrangements, while figs. 13A - 13C show various horizontal cross- sections taken as indicated in Fig. 12. More specifically, Fig. 13 A shows the top view of a set of upper anchor brackets 28, Fig. 13B shows a top view of a set of guide brackets 33, 39, and Fig. 13C shows a top view of a set of lower anchor brackets 29.

Figure 14 shows an elevational view of an upper anchor bracket 28, while Fig. 15 shows an elevational view of a lower anchor bracket 29. Therein, the several reinforcing bracing members 50 may be appreciated as welded members upon a back support plate 56. The back support plate 56 is configured to fit flush, in a face-to-face orientation against an exterior surface of the pole 3. In the illustrated embodiment, the support plate 56 is flat, but may be variously configured to conform to the exterior of the pole 3 upon which it is intended to be applied. The anchor plate 53 is shown in a substantially horizontal orientation and is supported by several of the provided brace members 50.

One advantageous aspect of the heretofore-described embodiment of the present invention is the way in which the anchorages 27 are joined to the utility pole 3. Apertures or holes 57 are provided in the support plate 56 which are aligned with mating holes in the utility pole 3. From a practical standpoint, the apertures 57 are typically initially provided in the support plate 56, and then the support plate 56 is utilized as a template for drilling the mating holes in the utility pole 3. Fixing bolts are then inserted through the aligned holes of the support plate 56 and the utility pole 3 for establishing their relative location. In the event that the position of the anchor bracket 27 is at an overlapped region or joint 18 of two sections 15, the through apertures are provided across the support plate 56 and both of the adjacent pole sections.

An added benefit of this fastening configuration is that it fixes all three of the components relative to one another by such cross-positioned bolts. This can be of critical importance because of the tension/compression action in the reinforcing rods. More specifically, if significant relative movement occurs between the sections 15 at an overlap 18 across which the reinforcement arrangement 25 extends, the tensioning or compression capability of the rod 30, 36 may be obviated. By extending the connective bolts across the support plate 56 and each of the two pole sections 18, this possibility is substantially eliminated.

It is also a significant feature of the present invention that bolt-type connections are used, as opposed to welded connections. As intimated hereinabove, this prevents the compromise of galvanization on the utility pole 3. Still further, blind-side fasteners, also known as anchor-type expansion bolts, can be utilized so that no manipulation is required within the interior of the utility pole 3 for the securement of the anchor brackets 27 thereupon - that is, these types of fasteners are essentially self-securing. Still further, the use of expansion bolts avoids having to tap the holes in the pole 3 for threaded engagement.

Fig. 16 provides an elevational view of a rod guide arrangement 33, 39. As illustrated, the rod guide 33, 39 is primarily composed of a ninety-degree angle boltable through apertures to the utility pole 3 in a manner similar to that used to secure the anchor brackets 27 to the pole 3. A second closure plate 54 is then bolted to the horizontal and outwardly projecting leg of the angle about the rod, details of which are shown in Fig. 31 A - 31F.

An alternative configuration of the reinforcement arrangement is illustrated in Figs. 17-24. Therein, a ring or collar arrangement 80 is shown that is fixed about the periphery of the utility pole 3 regardless of the shape of the pole 3. In this alternative design, a collar 83 serves as a substitute for the back plate of a plurality of anchors to be positioned at a similar elevation upon the utility pole 3. Otherwise, the construction of the anchor bracket can be similar to that disclosed and described hereinabove. As illustrated, however, the collar 83 is exemplarily made up of two halves 85 that are joined together to form a surrounding ring 83 about the utility pole 3. Like the back plates 56 of the individual brackets 28, 29, the collar 83 is positively connected via expansion bolts through aligned apertures in the collar 83 and utility pole section(s).

Fig. 18 diagramatically illustrates that the rods 30, 36 may be advantageously offset slightly from vertical. This orientation is depicted in Figs. 17 and 18 as different eccentricities of a particular rod 30, 36 between the top and bottom ends of the rod and the centroid of the utility pole. As a result, this vertically offset orientation is generally accommodated by a similar angular offset from horizontal of the anchor plate 53 in the bracket assembly. This matching offset is provided to assure a square relationship between the abutting nut 55 on the rod 30, 36 and the contact surface of the anchor plate 53.

Figs. 19-24 illustrate details of an exemplary collar assembly 80 in which: Fig. 19 is an elevational view; Fig. 20 is a sectional view looking downward at two halves 85 of a collar 83 installable about a utility pole 3 (but not yet secured together); Fig. 21 is a side elevational view of a guide 33, 39 for a rod 30, 36; and Fig 22 is a secured (bolted-together) configuration of the two-half collar 83 of Fig. 20. Fig. 23 is a detailed view of a midsection of one of the collar halves 85 and Fig. 24 is a detail of bolted flanges forming a secured joint between two collar halves 85.

Figs. 25 and 26 again depict the lower 29 and upper 28 anchor brackets, respectively. Figs. 27-29, however, provided details of the back support plate 56, the several brace members 50 and the anchor plate 53 as each relates to the upper anchor bracket 28 of Fig. 26. Fig. 30 shows details of an exemplary connection between the back plate 56 and the anchor plate 53.

Figs. 31 illustrate components of a rod guide assembly 33, 39. Fig. 31 A shows a slotted guide bracket member 52 that attaches directly to the utility pole 3. A U-shaped slot or recess is provided in the horizontally oriented plate for accepting a tension rod therein. Fig. 3 IB illustrates a closure plate 54 that is bolted upon the receiving plate as shown in Fig. 31C for enclosing a tension rod. As described hereinabove, however, the size of that through-aperture or slot for the rod is appropriately sized to accommodate longitudinal movement of a captured rod, but to limit lateral movement (particularly side-to-side) which could inhibit the operative qualities thereof. Fig. 3 ID similarly depicts the guide assembly 33, 39 as shown in Fig. 16 and Fig. 31E illustrates the support angle of the guide assembly alone, and Fig. 3 IF illustrates a top view of the guide arrangement's through-aperture for a tension rod.

Referring again to the embodiment of the invention in which individual anchor brackets 28, 29 are used, as opposed to anchor collars 80, a superior method for reinforcing utility poles 3 is enabled. Referring to Fig. 7, the installation of anchor brackets 28, 29 alongside existing and exteriorly located cabling 8 is shown. By utilizing such individual anchor brackets 28, 29, installation of the entire reinforcement arrangement 25 can be accomplished without disturbing either the existing cable configuration, or the wireless services being provided therethrough. This is a significant advantage over other reinforcement procedures requiring either removal and then reinstallation of such cabling, or

even the temporary displacement of the cables.

Claims

CLAIMS:

1. A reinforcement arrangement for an utility pole, said arrangement comprising:

a plurality of anchorages, each of said anchorages configured to be located at a

different vertical position on an utility pole; and

a tension member configured to be coupled between at least a pair of said

anchorages for increasing the load capacity of a receiving utility pole when thereby

fortified.

2. A reinforced utility pole arrangement comprising: an utility pole configured to receive above-ground appurtenances; a plurality of anchorages, each of said anchorages located at a different vertical

position on said utility pole; and a tension member configured to be coupled between at least a pair of said anchorages for increasing the load capacity of a receiving utility pole when thereby

fortified.

3. The arrangement as recited in claim 2, further comprising:

said plurality of anchorages located at on exterior surface of said utility pole.

4. The arrangement as recited in claim 2, further comprising:

said plurality of anchorages coupled to an exterior surface of said utility pole.

5. The arrangement as recited in claim 2, further comprising: said plurality of anchorages fastened to an exterior surface of said utility pole.

6. The arrangement as recited in claim 2, further comprising:

said utility pole comprising a plurality of stacked pipe sections; and

an overlap-joint formed between adjacent stacked pipe sections; and

a portion of at least one of said plurality of anchorages extending across said overlap-joint

thereby fixing said adjacent stacked pipe sections against relative movement.

7. The arrangement as recited in claim 2, further comprising: a tension member guide positioned on said utility pole at a vertical location between said pair of said plurality of anchorages, said tension member guide adapted to receive a tension member therethrough.

8. The arrangement as recited in claim 7, further comprising: said tension member guide adapted to permit translating vertical movement of a

tension member therethrough and to limit lateral movement of said tension member

relative to said guide.

9. The arrangement as recited in claim 2, further comprising:

said tension member being oriented to have a varying eccentricity with respect to

said utility pole.

10. The arrangement as recited in claim 2, further comprising: each of said tension members being connected to at least one of said anchorages

and unidirectionally secured against translational movement relative thereto.

11. The arrangement as recited in claim 2, further comprising:

a compression member configured to be coupled between at least a pair of said anchorages for increasing the load capacity of a receiving utility pole when thereby

fortified.

12. The arrangement as recited in claim 11, further comprising:

a compression member guide positioned on said utility pole at a vertical location between said pair of said plurality of anchorages, said compression member guide

adapted to receive a compression member therethrough.

13. The arrangement as recited in claim 12, further comprising: said compression member guide adapted to permit translating vertical movement

of a compression member therethrough and to limit lateral movement of said tension member relative to said guide thereby preventing buckling of said compression member

when under compression.

14. The arrangement as recited in claim 11, further comprising:

said compression member being oriented to have a varying eccentricity with

respect to said utility pole.

15. The arrangement as recited in claim 11, further comprising: each of said compression members being connected to at least one of said pair of

anchorages and being unidirectionally secured against translational movement relative

thereto.

16. The arrangement as recited in claim 11, further comprising:

each of said compression members being connected to at least one of said pair of

anchorages and being bidirectionally secured against translational movement relative

thereto.

17. The arrangement as recited in claim 2, further comprising: at least one of said anchorages being positioned upon a collar, said collar surrounding and fastened about said utility pole.

18. The arrangement as recited in claim 2, further comprising: a plurality of said anchorages being positioned upon a collar, said collar surrounding and fastened about said utility pole.

19. The arrangement as recited in claim 18, further comprising:

said plurality of said anchorages positioned upon said collar being located at

substantially the same vertical position relative to said utility pole.

20. The arrangement as recited in claim 2, further comprising:

a plurality of said anchorages being positioned upon a plurality of collars, each of

said collars surrounding and fastened about said utility poles and each of said plurality of

collars being oriented substantially parallel with the other of said plurality of collars.