WO1997021258A1

WO1997021258A1 - Tower structure

Info

Publication number: WO1997021258A1
Application number: PCT/GB1996/002931
Authority: WO
Inventors: Graeme Hill; William Neilson; Dale Sinclair
Original assignee: Dynamic Concepts
Priority date: 1995-12-01
Filing date: 1996-11-29
Publication date: 1997-06-12
Also published as: AU7701496A; EP0864185A1

Abstract

There is described a tower structure for supporting telecommunications transmission equipment. The structure is in the form of a tubular mast having a first set of arm members extending radially outwards from the top of the mast and a second set of arm members aligned with the first set of arm members and extending radially from the mast below the first arm members. The structure further is provided with elongate bracing members joining the arm members.

Description

"Tower Structure"

This invention relates to a tower structure and especially but not exclusively to an antenna support structure designed for use in the telecommunications industry.

With the increasing use of portable telephones and of cellular telecommunications networks generally, there is a need for increasing numbers of support structures (masts and towers) for telecommunications equipment and antennae. The following problems exist with such structures:

1. Planning approvals for the use of the currently available masts and towers are becoming increasingly difficult to obtain. This is due to the number of masts and towers being erected by the major telecommunication companies and the resultant negative impact on the environment. Aesthetic considerations are becoming important factors in determining planning applications.

2. The current towers and masts are typically either lattice structures or monopole structures. These utilise technology from other industries (electricity pylons and motorway lighting masts) and have not been designed specifically with the telecommunication industry in mind. Lattice style towers are visually unattractive and onopole masts must be restricted to modest heights for telecommunications applications because of their tendency to sway.

3. With local authorities and the government aiming to improve the quality of design in the environment the need for a purpose designed telecommunication structure has become essential. This fact is supported by the introduction of an appearance assessment category in recent UK planning legislation and by the increasing number of press articles about the lack of aesthetic design used for utility structures.

In accordance with the present invention there is provided a tower structure, for supporting telecommunications transmission equipment or the like, comprising: a generally tubular mast; a first plurality of arm members secured to and extending radially outwards from said mast adjacent the upper end thereof; at least a second plurality of arm members corresponding in number to said first arm members, secured to and extending radially outwards from said mast below and in angular alignment with said first arm members; and a plurality of elongate bracing members, one of said bracing members extending between each pair of vertically adjacent, angularly aligned arm members and between each of the lowermost of said arm members and the ground adjacent the base of said mast. Preferably, said first arm members are at least three in number.

Preferably also, the arm members of each plurality of arm members are spaced substantially equiangularly about said mast.

Preferably, said mast is generally circular in horizontal cross section, and most preferably is substantially generally cylindrical.

Preferably also, the tower includes at least a third plurality of arm members corresponding in number to said first arm members, secured to and extending radially outwards from said mast in angular alignment with said first plurality and said second plurality of arm members, said third and subsequent pluralities of arm members being located intermediate said first and second pluralities of arm members.

Preferably also, said mast comprises a plurality of tubular sections of predetermined lengths secured end to end in sufficient number to make up a mast of the required height. Preferably also, each of said sections has a plurality of said radial arm members associated therewith. A mast may therefore be assembled on site from a selection of parts including the correct number of tubular sections to make a mast of the required height, a number of pluralities of arm members adapted to be attached to said tubular sections and a number of bracing members.

Most preferably, said arm members of said first plurality of arm members have a first predetermined length, said arm members of said second plurality of arm members have a second predetermined length greater than the first, and any succeeding pluralities of arms have predetermined lengths greater then the length of said arm members of said first plurality and less than the length of the arm members of said second plurality.

There may be provided a substantially conical member at the top of said mast. Said substantially conical member may include light emission means.

Preferably the lengths of said arm members of said respective pluralities are such that, in use, the bracing members are inclined at less than 25° away from the vertical and most preferably at about 10° away from the vertical.

The advantages of the invention and/or the ways in which the disadvantages of previously known arrangements are overcome, include:

1. The antenna support structure has been designed to suit the specific structural requirements of the telecommunication industry; i.e.

A The need to limit movement (sway) at the head of the structure; and

B The requirement for the structure to support varying arrangements of antennas (loading patterns) .

The antenna support structure achieves these requirements by utilising a range of components: circular hollow sections, castings and elongate bracing members.

2. The disadvantage of existing towers is that they are designed using either a range of small scale components such as angles (lattice towers) or large scale components such as seamless welded tubes (lighting masts) . This means that the scale of the towers or masts is either problematic from close up, or from a distance. The towers which use small scale components are visually heavy close up, and from a distance. These towers also do not appear, visually, capable of supporting the dishes which are fixed to them and the dishes have to be fixed to the outside of the structure. The towers which use large scale components are visually acceptable from a distance but appear heavy close up.

The proposed antenna support structure resolves this problem by creating a hierarchy of components which are put together in a way which creates a solution appropriate when viewed from a distance or close up. This is achieved by using components of different weights (the circular hollow sections and the bracing members) and components capable of being modelled (the castings). A further advantage is that the antennas may be fixed to the circular hollow section which not only looks as if it is capable of supporting the antennas but as they will be positioned close to the centre of the structure the overall visual mass will be reduced when these are added.

3. Due to the triangular plan of the preferred embodiment and the strong definition of the castings the silhouette is unique and presents an identity which will differentiate the antenna support structure from current designs, which can be associated with other uses, and provides an identity which will be specific to the telecommunication industry. 4. The identity of the antenna support structure is achieved not only during the day but also at night by the addition of a lighting cone which caps the structure. Current masts and towers have no identity at night.

5. The antenna support structure has been designed as a kit of parts unlike the current towers which are fabricated as one-off structures. This enables a family of standard castings and spine components to be used.

6. The antenna support structure provides increased flexibility over existing towers and masts as it can be manufactured in smaller sections to give a greater range of heights to the user thus creating a unique family of antenna support structures.

7. At present the towers and masts utilised are manufactured by specialist companies. The present antenna support structure will allow alternative procurement strategies to be investigated.

8. The current towers and masts are all prefabricated and bolted together on site. The present antenna support structure offers the possibility of varying degrees of prefabrication and site erection which can be altered to suit the difficulties associated with accessing each site.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Fig. 1 is a schematic side view of a first embodiment of a tower structure embodying the invention; Fig. 2 is a schematic side view of a second embodiment of a tower structure embodying the invention, having items of telecommunications equipment mounted thereon; Fig. 3 is a schematic side view of a family of towers of differing heights, all embodying the invention; Figs. 4(a), 4(b) and 4(c) are plan views of, respectively, first and second prior art tower structures and of a tower structure embodying the present invention; Fig. 5 is a fragmentary perspective view of a portion of a tower structure embodying the invention; Figs. 6(a), 6(b), 6(c) and 6(d) are schematic illustrations of types of radial arm forming part of tower structures embodying the invention; Fig. 7 illustrates a kit of parts for assembling a tower structure in accordance with the present invention; Fig. 8 is a schematic side view of a family of towers of differing heights, in accordance with preferred embodiments of the invention; Figs. 9(a), 9(b), 9(c), 9(d) and 9(e) are more detailed side views of each of the tower structures of Fig. 8; Fig. 10 is a sectional view on line X-X of Fig. 9(a); Fig. 11 is a fragmentary side view of a portion of the tower structures of Figs. 9(a) - 9(e); Figs. Dl - D9 are detail views of portions of the tower structures of Figs. 9(a) - 9(e); Figs. 12(a) - 12(g) are, respectively, side, plan and sectional views of three uppermost radial arms of the tower structures of Figs. 9(a) - 9(e); Figs 13(a) - 13(e), 14(a) - 14(e), 15(a) - 15(e), 16(^a) -16(^e) ^anc* 17(a) - (e) are respectively, side, plan and sectional views of further radial arms of the tower structures of Figs. 9(a) - (e); and Figs. 18(a) and 18(b) are, respectively, plan and side views of an example of a masthead structure suitable for use with the tower structures of Figs. 9(a) - 9(e) .

The tower structure in accordance with the invention, intended particularly for use as an antenna support structure for the telecommunications industry, comprises the following four elements:

1 A tubular mast forming a spine. The circular section spine is preferably manufactured in sections and is the main structural element of the antenna support structure upon which antennas are supported and from which access is gained.

2 Horizontal (radial) arms. These arms occur at varying vertical increments and are suitably formed using cast steel. The arms allow the guys (cables) or other bracing members to be pulled into a more acute angle by transferring moment forces from the mast into the arms. This allows the antenna support structure profile to be slimmer than traditional guyed structures.

3 Cables/bracing members. The cables or other bracing members, which act as guys to the mast via the arms, restrict sway movement of the antenna support structure to acceptable levels.

4 Lighting cone. A cone caps the tower structure allowing the structure to be illuminated. Referring now to the drawings, Figs. 1 to 3 show examples of tower structures in accordance with the invention, of varying heights. In each case the tower structure comprises a central, circular section, tubular mast 10 and at least two vertically spaced tiers of radially extending arms 12. Each tier of arms 12 comprises at least three (preferably three) arms spaced equiangularly around the mast 10. The outer ends of each angularly aligned pair of vertically adjacent arms 12 are interconnected by elongate bracing members 14, which also connect the lowermost arms 12 to the ground or tower foundation. In the embodiments of Figs. 1 to 7 , the elongate bracing members 14 comprise cables. The bracing members 14 are placed in tension and act as guy lines to restrain swaying motion of the mast 10.

The lengths of the arms 12 in each tier increases from the top to the bottom of the structure, so that the bracing members extend outwardly at an angle from their uppermost points. The angle of inclination of the bracing members 14 is preferably less than 25°, most preferably 10°.

A conical cap 16 at the top of the mast 10 may enclose a light source (not shown) .

Fig. 1 shows telecommunications antennae 20, 22 mounted on the tower. The telecommunications equipment which is supported by the structure does not form part of the claimed invention. The nature and placement of such equipment will vary. In general, however, items may be mounted on the mast head portion above the uppermost tier of arms 12, or may be secured to the mast 10 between adjacent tiers of arms 12. Fig. 4 shows a comparison between plan views of a conventional lattice-construction tower 24 (Fig. 4(a)), a conventional monopole (welded tube) mast 26 (Fig. 4(b)) and the present invention (Fig. 4(c)).

The masts 10 are preferably constructed in modular form from sections of tubing, the arms 12 being bolted to the tubing. Figs. 5 and 6 illustrate the general form of the arms 12, which are suitably cast from steel and taper in the radially outward direction in both plan and side views. Apertures 28 are formed in the arms 12 to reduce weight and wind resistance, and to improve the visual appearance of the structure. The bracing members 16 pass through or are connected to eyelets 30 formed at the outer ends of the arms 12.

In the examples of Figs. 1 to 6, the tubular sections of the mast between the uppermost and lowermost sections are all identical, allowing the structure to be constructed from a minimum number of different parts. Fig. 7 illustrates a kit of parts for a tower, comprising an upper mast section 32, lower mast section 34, intermediate mast sections 36, sets of arms 12, conical cap 16, and guy line cables 14. The completed tower would also include the telecommunications apparatus 20, 22.

As seen in Fig. 3, the design of the tower can be extended to any required height by the addition of mast sections 36 and additional arms 12. Typical telecommunications towers will be in the range 15 meters to 30 meters in height.

Figs. 8 to 18 illustrate particularly preferred embodiments of the invention. Fig. 8 again shows a family of towers ranging in height from 15 meters to 28.5 meters. The basic design of these embodiments is essentially the same as those of Figs. 1 to 7, comprising a central mast 110, radial arms 112, bracing members 114 and conical caps 116. The most significant differences are as follows.

The smaller towers have a mast of substantially uniform cross section as before. However, for the larger towers, the lowermost portion 150 of the mast 110 has a larger diameter than the upper portion 152. Also, the bracing members 114 comprise rigid steel tie-rods rather than flexible cables, and the masthead portion 154 includes modified arms 156, a supporting framework 158 mounted on the arms 156 for the masthead telecommunications equipment 120. Fig. 8 also includes a plan view 160 of the masthead portion 154 and a plan view 162 illustrating the mounting of additional antennae 122 to the mast 110 itself.

It will be appreciated that most, if not all, of the components making up the smaller towers can be used for the upper portions of the larger towers, which are all substantially identical, as indicated by the dash and double-dot lines 164 in Fig. 8.

Figs. 9(a) to 9(e) illustrate the towers of Fig. 8 in greater detail, and Figs Dl to D9 show enlarged and/or exploded and/or sectional views of details Dl to D9 circled in Figs. 9(a) to 9(e).

Fig. Dl illustrates the connection between two upper/smaller diameter mast sections 136, using a tubular stub 200 which is welded to the interior diameter of the upper end of the lowermost of the two mast sections . The lower end of the uppermost mast section is fitted over the end of the stub 200 and secured with bolts or the like.

Fig. D2 illustrates the connection between a lower/larger diameter mast section 138 and an upper/smaller diameter mast section 136. A tapered portion 202 reduces the diameter of the lower section 138 to that of the upper section 136, the sections 136 and 138 being connected together by means of a stub 200 as in Fig. Dl .

Fig. D3 illustrates the connection of two lower/larger diameter mast sections 138, using a tubular stub 204 in a manner similar to Fig. Dl .

Fig. D4 illustrates the base of the smaller towers of Figs. 9(a) and 9(b), and the manner in which the base of the tower is secured to a suitable foundation. A baseplate 206 is secured to the base of the mast 110. The baseplate 206 is circular and has a diameter larger than that of the mast 110, stiffener plates 208 being welded into the angle between the mast 110 and the baseplate 206. The baseplate 206 is secured to an anchor plate 210 in the foundation using bolts 212 spaced around the circumference of the baseplate 206. An earthing plate 214 is also secured to the baseplate 206.

Fig. D5 illustrates the base of the larger towers of Figs. 9(c) 9(d) and 9(e) . The larger towers are secured to a foundation in a manner similar to that of Fig. D4 , with baseplate 206, stiffeners 208, anchor plate 210 and bolts 212.

Fig. D6 illustrates the mounting of an access ladder 166 to the mast 110. The ladder comprises a vertical member 216 secured to the mast at intervals by horizontal members 218. Rungs 220 are secured to the vertical member 216.

Fig. D7 illustrates the manner in which the tie rods 114 are coupled to the ends of the arms 112, using lock nuts 222 and a tensioning coupler 224.

Fig. D8 illustrates the manner in which the arms 112 are secured to the mast 110. Arm supporting fixtures 226 are secured to the mast 110 and the arms 112 are attached to the fixtures 226 by means of bolts 228. Fig. D9 illustrates the manner in which the lowermost tie rods 114 are secured to the foundation by means of a baseplate 230 secured to anchor plates 232 in the foundation by means of bolts 234. A turnbuckle 236 is connected to the tie rod 114 above the baseplate connection.

Fig. 10 illustrates a typical cross section of the towers at line X-X of Fig. 9(a), including the access ladder 166. Fig. 11 shows a typical tier of arms 112 mounted on the mast 110.

The embodiments of Figs. 9(a) to 9(e) utilise a total of six types of arm, designated by the reference numerals 170, 172, 174, 176, 178 and 180. These different arm types are illustrated in greater detail in Figs . 12 to 17.

Fig. 12 shows the uppermost arms 170, which are adapted to support a masthead structure. The outer ends of the arms 170 are cranked upwards and are fitted with transverse arms 236, 238 for connection to portions of the masthead structure (illustrated in Figs. 18(a) and 18(b)). Figs. 12(c) - (g) are sectional views on lines 1 to 5 respectively of Figs. 9(a) and 9(b).

Figs. 13 to 17 show the other types of arm 172 to 180 in order of increasing length. In each case, Figs, (c) - (e) show sectional views on lines 1 to 3 or 4 to 6 of Fig. (a).

The arms 170 to 180 all generally comprise an I-section inner portion having apertures formed therein.

Figs. 18(a) and 18(b) illustrate one example of a masthead structure comprising a framework 158 for supporting masthead telecommunications components, the framework 158 itself being supported by the modified, uppermost arms 170 (156 in Fig. 8). The configuration of the masthead structure may vary according to need. Accordingly, the present example will not be described in detail. Fig. 18(b) also shows a lightning rod 240 attached to the upper end of the mast adjacent the conical cap 116.

Improvements and modifications may be incorporated without departing from the scope of the invention.

Claims

1. A tower structure, for supporting telecommunications transmission equipment or the like, comprising: a generally tubular mast; a first plurality of arm members secured to and extending radially outwards from said mast adjacent the upper end thereof; at least a second plurality of arm members corresponding in number to said first arm members, secured to and extending radially outwards from said mast below and in angular alignment with said first arm members; and a plurality of elongate bracing members, one of said bracing members extending between each pair of vertically adjacent, angularly aligned arm members and between each of the lowermost of said arm members and the ground adjacent the base of said mast.

2. A tower structure as claimed in Claim 1, wherein said first arm members are at least three in number.

3. A tower structure as claimed in Claim 2, wherein the arm members of each plurality of arm members are spaced substantially equiangularly about said mast.

4. A tower structure as claimed in any preceding Claim, wherein said mast is generally circular in horizontal cross section.

5. A tower structure as claimed in Claim 4, wherein said mast is substantially generally cylindrical.

6. A towere structure as claimed in any preceding Claim, wherein the tower includes at least a third plurality of arm members corresponding in number to said first arm members, secured to and extending radially outwards from said mast in angular alignment with said first plurality and said second plurality of arm members, said third and subsequent pluralities of arm members being located intermediate said first and second pluralities of arm members.

7. A tower structure as claimed in any preceding Claim, wherein said mast comprises a plurality of mast sections of predetermined lengths secured end to end in sufficient number to make up a mast of the required height.

8. A tower structure as claimed in Claim 7, wherein each of said mast sections has a plurality of said radial arm members associated therewith.

9. A tower structure as claimed in Claim 7 or Claim 8, wherein said mast is adapted to be assembled on site from a kit of parts comprising a number of mast sections to make a mast of a required height, a number of pluralities of arm members adapted to be attached to said mast sections and a number of bracing members.

10. A tower structure as claimed in any preceding Claim, wherein arm members of said first plurality of arm members have a first predetermined length, said arm members of said second plurality of arm members have a second predetermined length greater than the first, and any succeeding pluralities of arms have predetermined lengths greater then the length of said arm members of said first plurality and less than the length of the arm members of said second plurality.

11. A tower structure as claimed in any preceding Claim, further including a substantially conical member at the top of said mast.

12. A tower structure as claimed in Claim 11, wherein said substantially conical member includes light emission means.

13. A tower structure as claimed in any preceding Claim, wherein the lengths of said arm members of said respective pluralities of arm members are such that, in use, the bracing members are inclined at less than 25° away from the vertical and most preferably at about 10° away from the vertical .