WO2005068730A1

WO2005068730A1 - Self-stable prefabricated foundation for towers

Info

Publication number: WO2005068730A1
Application number: PCT/PT2005/000002
Authority: WO
Inventors: Joaquim Augusto Martins Nogueira De Almeida
Original assignee: Proconsultores-Engenharia E Arquitectura, Lda
Priority date: 2004-01-19
Filing date: 2005-01-19
Publication date: 2005-07-28
Also published as: BRPI0506463A; PT103061A; EP1716294A1

Abstract

A self-stable prefabricated foundation for towers with a base of three pieces of prefabricated reinforced concrete, linked with metallic profiles and stabilized with prefabricated reinforced concrete counterweights.

Description

DESCRIPTION

SELF-STABLE PREFABRICATED FOUNDATION FOR TOWERS

FIELD OF THE INVENTION

The present invention relates to foundations for towers in general and in particular for telecommunications towers, radar towers and similar applications.

BACKGROUND OF THE INVENTION

The execution of telecommunications networks comprises a series of telecommunications towers in such a way as to cover the areas that are intended to be covered and usually these towers, of varied dimensions, are installed in an open field.

In traditional foundations of reinforced concrete cast in si tu, the metallic towers are fixed to the foundations by means of anchor bolts according to the loads and geometry of the towers. This traditional construction technique takes up a relatively large amount of time due to the excavation needed and the curing of the concrete needed to achieve the necessary resistance to support the tower.

Telecommunications companies need to set up telecommunications towers quickly due to the great growth of their own networks, as well as the fact that they have been having difficulties in obtaining the licences for the respective construction.

According to the present invention the tower, the foundation is composed of 3 prefabricated reinforced concrete pieces, mounted side by side in the correct order and then assembled with 4 steel profiles. Afterwards, 2 identical groups of counterweights are put in place, on top of the steel profiles on each side of the tower place.

All this assembling is carried out very quickly, namely because it totally dispenses with excavation and does not need any type of waiting for concrete casting, concrete curing or an embankment, making it possible to erect the tower in the same day.

Although not usual, telecommunications companies sometimes need to change the site location or have a higher tower in order to rectify or expand their network coverage. The traditional method does not give the possibility of changing the location of the tower foundation, nor does it give an easy way of providing greater load resistance.

With the present invention it is easier to dismantle the entire tower and assemble the foundation in another location. It is also easy to add more height to the tower and it is simply necessary to put supplementary counterweights on the base to give the necessary extra load resistance.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a frontal view of the set of the tower with the base and the counterweight according to the present invention.

Figure 2 is a side view of the set of the tower with the base and the counterweight according to the present invention.

Figure 3 is a plan view of the levelled ground to set up the base and the electric grounding cables and connections

Figure 4 is a plan view of the 3 pieces that constitute the base with the infrastructures to pass all kinds of cables to the equipment connections inside the prefabricated concrete slabs. This figure also shows the location of the fixed bolts to fix the H200B steel profiles.

Figure 5 is a plan view with the steel profile structure that is incorporated inside of one of the prefabricated concrete pieces, and that secures the tower by means of the welded anchor bolts. This figure shows also the 4 steel profiles that are fixed to the 3 prefabricated slabs and assembled all together.

Figure 6 is a plan view of the site, the tower base with the steel profiles and the counterweights. We can also see the plan of the telecommunications tower, the outdoor type of electronic telecommunications equipment and the electric main board.

Figure 7 is a sectional view of the securing detail of the steel profiles that assemble the 3 base slabs.

DETAILED DESCRIPTION OF THE INVENTION

The present invention refers to a tower foundation in general and in particular for telecommunications towers, radar towers and similar applications, which is quickly assembled, can be disassembled, transported to another location and reassembled.

All the pieces are prefabricated and can be assembled on almost any kind of ground without excavation or concrete cast levelling.

The natural ground 1 must be levelled to horizontally mount the base 3. The base 3 is a set of 3 pieces of prefabricated reinforced concrete with the dimensions of 5 m in length, 2.4 m in width and 0.2 m in thickness, but they can have other dimensions adapted to the engineering calculations, transport conditions, lifting conditions or site surface needed.

The base pieces are placed side by side in the correct sequence according to the location of the manhole boxes 7, the boxes for the electric grounding connections 8, the tubes inside of the concrete slabs for power cables 5, the tubes inside of the concrete slabs for telecommunications cables 6 and electric grounding cables 9, according to fig. 4.

The hole 18 that exists in the concrete base, fig. 4, is for the passage of the lightning protection cable from the tower to the grounding connection.

The location of boxes 7 and 8, the tubes 5 and 6 and the grounding cables can be changed according to the needs of the telecommunications equipment .

The base 3 has a thickness of 0.2 m in order to its top surface has an easy access from the outside ground to people and equipment .

The entire base after assembly defines the total site surface, which includes the tower 13 and telecommunication equipment 16, being its perimeter the location of the fence and access gate 14, also avoiding the need for fence post foundations . The base slabs 3 are fixed by the concrete bolts 4 aligned according to the securing of the steel profiles 11. These bolts 4 are inserted according to the quantities expressed in fig. 4 and they exist to mobilize all the base slabs to the tower 13 loads, although location and quantities of the bolts depend on the structural calculations. The steel profiles 11 are calculated in order to the loads of the tower be distributed to all site base. They are fixed with bolts 4, nails 22 and nuts 20 according to fig. 7.

In figure 1, we can see the set of the tower 13 with base slabs in prefabricated reinforced concrete 3, the steel profiles 11 and the prefabricated reinforced counterweights .

The tower 13 can be any kind of type of tower, monopole, triangular or quadrangular, in steel, concrete or GRC (Glass fibre Reinforced Concrete) , and with different dimensions. According to the type of tower, the solution for securing the base is adapted taking into consideration the structural calculations that will define the quantities and location of the anchor bolts 10, and the steel structure that goes inside of the concrete slab 19.

Figure 2 shows the ground levelling 1 with the implantation surface and the electric grounding cables 2 and the lightning protection cables. The steel profile structure 19 is incorporated into the concrete and has the function of transferring the loads of the tower 13 through the anchor bolts 10 to the concrete slab. Its function is also to reduce the stresses / strains due to localized tower reactions and mobilize the stable weight of the counterweights through the steel profiles 4 and all the concrete slabs of the base 3.

Claims

1. A self-stable prefabricated foundation for towers is characterized, by a base of three pieces of prefabricated reinforced concrete, linked with metallic profiles and stabilized with prefabricated reinforced concrete counterweights.

2. The base according to claim 1, characterized by a rectangular shape and composed of three pieces also with a rectangular shape and with the same dimensions and a maximum width of 2.4 m, to be transportable without the need for special transportation.

3. The base according to claim 2, characterized in that it incorporates in its thickness the tubes for the passage of power, telecommunications, grounding and lightning protection cables, as well as the inspection boxes for the future installation of the telecommunications equipment and tower.

4. The base according to claim 2 with one piece where the tower will be fixed, characterized in that includes in its thickness a structure of steel profiles that have anchor bolts welded for the securing the tower and it allows the transmission of the loads of the tower to the base.

5. The base according to claim 2, characterized in that it has a series of fixed screws on the top surface, aligned according to the positioning of the steel profiles to be set up.

6. The pieces of prefabricated reinforced concrete according to claim 1, characterized by the 20 cm thickness.

7. The pieces of prefabricated reinforced concrete according to claim 1, characterized in that they are reinforced with an electro welded mesh class S500 steel bar in two layers, an upper and a lower layer.

8. The structure of steel profiles according to claim 4, characterized by a series of type HE 160B steel profiles connected together by welding and in that it supports the anchor bolts to the tower.

9. The anchor bolts according to claim 8, characterized in that they are fixed by welding to the steel profiles that are built into the prefabricated reinforced concrete base and their dimensions, screws and shape are in accordance with the tower type to be supported.

10. The steel profiles according to claim 1 are hot galvanized type HE 200B of 6 m in length, fixed by means of steel plated nails fixing the steel profile to be screwed with a nut to the screws according to claim 5. -IO-

II. The prefabricated reinforced concrete counterweights according to claim 1, which have the dimensions of 1 m in width, 2.4 m in length and 0.2 m in height .

12. The counterweights according to claim 11, characterized in that they are reinforced with an electro welded mesh class S500 steel bar in two layers, an upper and a lower layer.

13. The counterweights according to claim 11, characterized in that they are placed one over the other in two identical groups over the metallic profiles mentioned in claim 10 in the base piece mentioned the claim 4.

14. The counterweights according to claim 11, characterized in that their quantities are to be defined by the height of the towers and respective loads transmitted to the foundation base.

15. The base according to claim 1, characterized in that it has the necessary dimensions to assemble the tower and all telecommunications equipment, be it in its shelter version or in the outdoor version, including the energy counters and boxes for arrivals of external connections.

16. The assembly of the tower, characterized by the assembly of its base in the anchor bolts mentioned in claim 9 with two nuts in each anchor bolt .

17. The base according to claim 15, characterized in that it is prepared for the assembly of a fence all around the site.

18. The base according to claim 15, characterized by the previous inclusion of the electric grounding cables to connect the fence and respective gate.

19. The assembly of the all the pieces according to claim 1, characterized in the following way: a. Cleaning of the ground and its levelling; b. Placing of the 3 base pieces in accordance with their own position; c. Assembly of the 4 HE 200B steel profiles and the respective securing with the nails and nuts according to claim 10; d. Assembly of the counterweight pieces; e. Assembly of the tower; f . Assembly of the fence; g. Assembly of the telecommunications equipment and its connections .

20. The self-stable prefabricated foundation for towers according to claim 1 do not have any structural metal part in direct contact with the ground due to the concrete protection to avoid corrosion problems.

21. All the groups of pieces according to claim 1 and the tower (up to 50 m in height) can be assembled and disassembled to transport the site to another location.

22. The self-stable prefabricated foundation according to claim 1 can be upgraded to support towers of between 25 m and 50 m in height, simply by upgrading the quantities of the counterweights according to claim 11 and claim 14.