WO2006116863A1

WO2006116863A1 - Modular segment of a tower

Info

Publication number: WO2006116863A1
Application number: PCT/CA2006/000697
Authority: WO
Inventors: Pierre-Guy Charette; Christian Vezina
Original assignee: Aat Inc.
Priority date: 2005-04-29
Filing date: 2006-05-01
Publication date: 2006-11-09
Also published as: CA2606335A1; CN101203648A

Abstract

There is provided a modular segment for a tower which provides additional strength and resistance against deflection due to wind forces and/or weight caused by ice accumulation on the support guy wires. The modular segment has an elongated member and two fasteners mounted in a distal manner on the elongated member, each fastener having at least two fastening points. The modular segment also has at least one tension element mounted on the elongated member, transversally to the elongated member and between the fasteners. Each tension element is provided with at least two anchor points evenly distributed around the elongated member. The modular segment is also provided with at least two wires, each being connected between the corresponding fastening points via the anchor points so as to be evenly distributed around the elongated member. Each of the wires is mounted under tension by means of the at least one tension element.

Description

MODULAR SEGMENT OF A TOWER

FIELD OF THE INVENTION

The present invention generally relates to towers for wind assessment, meteorological studies and telecommunication for example and more particularly to an improved modular segment for such a tower.

BACKGROUND OF THE INVENTION

The usage of temporary and permanent towers is well spread in the meteorological, communication and wind assessment fields. The tower needs to be as light as possible and must be erected with basic tools such as a gin pole for example. Such a tower is generally installed in more or less remote areas and is often in place for a definite period of time, from one day to 5 years or more.

The necessity for higher towers is mainly dictated by the wind energy industry which uses more and more powerful wind turbines. Such turbines have to be installed on top of tapered towers that are built higher than conventional towers to gain more wind speed. Energy production goes to the cube of the wind speed and each increase in wind speed translates into greater energy production.

As in the mining or petroleum industry, wind energy needs prospecting prior to the investment of a full-scale wind farm. This prospecting is performed using temporary towers mostly erected in remote or hard to access virgin areas thus requiring light weight and relatively inexpensive installation. The measured height needs to be as close as possible to the wind turbine hub height. With taller turbines, the necessity of higher wind assessment towers is increased. To prevent the collapse of these inexpensive wind assessment towers, improved solidity is required. Improved solidity can be achieved by increasing the wall thickness of the tubes with the consequence of substantially increasing the amount of material involved in the manufacturing and, thus, increasing the actual cost of the tower and its weight.

It would therefore be desirable to provide a mechanism that would increase the solidity and rigidity of a tower without a substantial increase in weight and cost.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a modular segment of a tower allowing to provide improved solidity to a tower, thereby allowing to form a tower of 60 meters in height or more.

Accordingly, there is provided a modular segment of a tower having an elongated member and two fasteners mounted in a distal manner on the elongated member, each fastener comprising at least two fastening points. The modular segment also has at least one tension element mounted on the elongated member, transversally to the elongated member and between the fasteners. Each tension element is provided with at least two anchor points evenly distributed around the elongated member. The modular segment is also provided with at least two wires mounted along the elongated member. Each of the wires is connected between the corresponding fastening points of the fasteners via the anchor points so as to be evenly distributed around the elongated member. Each of the wires is mounted under tension by means of the at least one tension element.

BRIEF DESCRIPTION OF THE DRAWINGS

A detailed description of preferred embodiments will be given hereinbelow with reference to the following drawings, in which like numbers refer to like elements.

FIG. 1 is a schematic representation of an 80-meter tower using several modular segments according to the present invention.

FIG. 2 is a front view of a modular segment of a tower according to the present invention.

FIG. 3 is a perspective view of the modular segment of a tower shown in

FIG. 2.

FIG. 4 is a schematic representation of the modular segment of a tower shown in FIG. 2 and illustrating the various forces in play.

The objects, advantages and other features of the present invention would become more apparent upon reading of the following non-restricted description of preferred embodiments thereof, given for the purpose of exemplification only with reference to the accompanying drawings. DESCRIPTION OF A PREFERRED EMBODIMENT

In the following description, similar features in the drawings have been given similar reference numerals and in order to weight down the figures, some elements are not referred to in some figures if they were already identified in a precedent figure.

The present invention concerns a modular segment of a tower allowing to provide a tower of improved solidity, thereby allowing, for example, to mount a tower of 60 meters in height and more.

Referring to Figure 1 , there is shown an 80-meter tower 10 having four modular segments 12 of definite length, 20 meters in the illustrated preferred embodiment, and which is supported by four sets of support guy wires 14 attached to the tower 10. Of course, any length for the modular segments 12 could be envisaged and any number of such segments 12 can be assembled together to provide a tower 10 of the convenient height required by a particular application. Preferably, as shown in Figures 2 and 3, the ends 16, 18 of the modular segments 12 are respectively provided with a coupling element (not shown) for coupling with another modular segment 12. Such coupling elements for coupling two sections of a tower are standard in the art and will not be described in more details.

The support guy wires 14 are attached to the ground via ground anchoring points 20. As illustrated, the same anchoring point can be used to anchor several support guy wires 14 to the ground. In the illustrated embodiment, two support guy wires 14 are anchored to the ground via the same ground anchoring point. Thus there are two anchoring points on both sides of the tower 10. It should be mentioned that in this illustrated embodiment, two other anchoring points are used in front of the tower and two other behind the tower. Of course, a person well versed in the art will understand that other arrangements could be used.

Referring to Figures 2 and 3, there is shown a modular segment 12 of a tower 10 according to the present invention. The modular segment 12 has an elongated member 22 and two fasteners 24, 26 mounted in a distal manner on the elongated member 22. Each of the fasteners 24, 26 is provided with at least two fastening points 28. In the present case, each fastener 24 or 26 is provided with four fastening points Preferably, as illustrated, each fastener 24, 26 is mounted at a respective end 16, 18 of the elongated member 22. The modular segment 12 has at least one tension element 30 mounted on the elongated member 22, transversally to the elongated member 22 and between the fasteners 24, 26. In the present case, two tension elements are provided. Each tension element 30 is provided with at least two anchor points 32 evenly distributed around the elongated member 22. In this embodiment, four anchor points 32 by tension element 30 are provided. The modular segment 12 has at least two wires 34, four wires 34 being used in the present case. The wires 34, preferably steel wires, are mounted along the elongated member 22. Each wire 34 is connected between the corresponding fastening points 28 of the fasteners 24, 26 via the anchor points 32 so as to be evenly distributed around the elongated member 22. Each wire 34 is mounted under tension by means of the tension element 30. In other words, the wires 34 are attached between the ends 16, 18 of the elongated element 22 and are put under tension with the help of the tension elements 30 that pushes the wires 34 away from the elongated element 22. In fact, the wires 34 are tightened to improve the radial strength of the modular segment 12. Such an improved radial strength advantageously allows for the additional weight imposed by the higher tower. Preferably, during their mounting, the wires 34 are pre-stretched to at least 75 percent of the limit of the cable. The tension of each cable is advantageously the same, preferably greater then 50 pounds but lower than 500 pounds.

In the illustrated embodiment, the four wires 34 are evenly distributed at 90 degrees around the elongated member 22. Two tension elements 30 are mounted in an evenly distributed manner on the elongated member 22, but it should be understood that any convenient number of tension elements 30 can be used, according the a particular application. Preferably, each tension element 30 has a collar 36 encircling the elongated element 22 and a plurality of arms 38 evenly mounted around the collar 36 and projecting transversally to the elongated member 22. In the illustrated embodiment, each tension element 30 is cross- shaped and has four arms 38 evenly distributed at 90 degrees around the elongated member 22, each being provided with one of the anchor points 32. Advantageously, for each wire 34, the corresponding fastening points 28 and anchor points 32 are aligned.

It is worth mentioning that, using one or more tension elements 30 with the modular segments 12 advantageously allows for a reduced number of support guy wires 14 to be used. This allows to reduce a possible ice accumulation on guy wires and to increase the individual support guy's ice loading limit. Each tension element 30 creates an additional stability nod that adds to the tower's rigidity. In this configuration, the tower 10 advantageously presents an increased stiffness to both wind drag occurring on the horizontal plane and weight occurring on the vertical plane. The pull-down on the tower 10 is also advantageously reduced by the usage of a reduced set of support guy wires 14. Adding one or more tension elements 30 increases the overall tower rigidity, this increased rigidity being put to contribution against the wind drag and wind torque while helping sustain the weight of frost and ice accumulation on the support guy wires 14. Indeed, the tension element 30 advantageously acts as a stabilizer when the tower 10 is erected. The wires 34 will contribute to the reactive radial force due to the wind drag and flexion due to weight. As previously mentioned, four wires 34 are preferably used but it should be mentioned that any number of wires could be contemplated, three for example.

Reference is now made to Figure 4 which shows a modular segment 12 of a tower 10 according to the present invention and a summary of the major forces acting thereon. The weight 40 of the above segments (not shown) including the downward pull of the support guy wires (not shown), with or without ice accumulation thereon, compresses the illustrated modular segment 12. The wind drag resulting of a wind loading 42 applies a force to the modular segment 12 causing a deflection thereof. This deflection will tend to stretch the guy wires. A resulting force 44 to the stretch of the guy wires will counteract the deflection 46 to reach an equilibrium point, which is within the buckling limit of the modular segment 12 for a predetermined weight and a predetermined wind speed.

People well versed in the art will understand that the mechanical characteristics of the modular segment of the present invention depend on a plurality of parameters such as the height of the tower and the speed of the wind to which the tower will be exposed, and have to be particularly adapted according to the need of a specific application. For example, for the lowermost modular segment of a tower having four steel modular segments whose elongated member is 39 feet long and has a support length between each opposed fastening points of 37 feet, deflection thereof will be calculated. The elongated member has an outside diameter of 6 inches, each of the four guy wires has a diameter of 0.1875 inch. For a specific wind speed of 50mph and an ice accumulation of 2 inches in diameter on the support guy wires, the compression force 40 is calculated. The wind loading 42 and the resulting force 44 are also determined and the resulting equilibrium deflection 46 can then be obtained. For the described example, the deflection thus obtained is around 1 inch at the reinforced points. These calculations are given as illustration purpose only and will not be further detailed.

Although preferred embodiments of the present invention have been described in detail herein and illustrated in the accompanying drawings, it is to be understood that the invention is not limited to these precise embodiments and that various changes and modifications may be effected therein without departing from the scope or spirit of the present invention.

Claims

WHAT IS CLAIMED IS:

1. A modular segment of a tower comprising: an elongated member; two fasteners mounted in a distal manner on the elongated member, each fastener comprising at least two fastening points; at least one tension element mounted on the elongated member, transversally to said elongated member and between the fasteners, each tension element being provided with at least two anchor points evenly distributed around the elongated member; and at least two wires mounted along the elongated member, each being connected between the corresponding fastening points of the fasteners via the anchor points so as to be evenly distributed around the elongated member, each of said wires being mounted under tension by means of the at least one tension element.

2. The modular segment according to claim 1 , wherein the tension element comprises a collar encircling the elongated element and a plurality of arms evenly mounted around the collar and projecting transversally to said elongated member, each arm being provided with one of the anchor points.

3. The modular segment according to claim 2, wherein each of said at least two fastening points comprises four fastening points, said at least two arms comprise four arms, said at least two wires comprising four wires.

4. The modular segment according to claim 1 , wherein the fastening points of each fastener are evenly distributed around the elongated member.

5. The modular segment according to claim 1 , wherein for each wire, the corresponding fastening and anchor points are aligned.

6. The modular segment according to claim 1 , having ends respectively provided with the fasteners.

7. The modular segment according to claim 1 , having ends each provided with a coupling element for coupling with another modular segment.