CONCRETE TOWER

DESCRIPTION

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0001] The invention relates to the building of annular concrete towers for wind power generators. In particular relates to a formwork for building an annular concrete tower.

2. Description of the Related Art

[0002] Arand, European Patent Application No. EP0960986A2, published on 1 December 1999, discloses a formwork for building an annular concrete tower. The tower is pre-stressed and it is conical, this is, the tower is a tapered structure of a circular cross-section where the diameter decreases with the height of the tower, so that the lower sections of the tower have a diameter bigger than the diameter of the upper sections of the tower.

[0003] Due to the fact that the tower of Arand is of a circular cross- section, it is necessary a formwork for every section of the tower, this increases the costs of the tower in addition in the case of the building of a wind park where multiple towers are going to be constructed, it is necessary to have a number of formworks in stock.

[0004] There is a need to provide a formwork for an annular tower using a formwork for building annular section, where the same formwork can be used for building sections of different diameter, this way reducing the number of formwork pieces necessary to have in stock. SUMMARY OF THE INVENTION

[0005] A first object of the invention consists in providing a formwork of a variable cross-section useful for building different segments of an annular pre-stressed concrete tower.

[0006] Another object of the invention consists of providing an annular tapered pre-stressed concrete tower having a triangular cross- section.

[0007] Another object of the invention consists of providing a method for erecting an annular tapered pre-stressed concrete tower.

[0008] All the objects of the invention are solved by providing a formwork comprising A formwork for casting concrete sections for a pre stressed concrete triangular cross-section annular tower, the formwork comprising:

- an inner formwork wall 1 comprising three inner flat sections 10 and three inner curved section 20,

o the inner flat sections 10 comprising multiple inner rectangular detachable panels 12, joined one adjacent to other, and inner trapezoidal detachable panels 15 each joined adjacent to the respective inner rectangular detachable panel placed on the lateral right and left ends; o the inner curved sections 20 comprised of an inner curved panel 22, joined to the trapezoidal panels

- an outer formwork wall 6 comprising three outer flat section 60 and three outer curved section 70,

o the outer flat sections 60 comprising multiple outer rectangular detachable panels 62, joined one adjacent to other, and outer trapezoidal detachable panels 65 each joined adjacent to the respective outer rectangular detachable panel placed on the lateral right and left ends; o the outer curved sections 70 comprised of an outer curved panel 72, joined to the trapezoidal panels an space 5 formed between the inner formwork wall 1 and the outer formwork wall 6

wherein

- the inner curved sections 20 are supported by a support 35 of an arrangement of horizontal, vertical and diagonal beans; and

- the outer curved sections 70 are supported by a support 85 of an arrangement of horizontal, vertical and diagonal beans,

to prevent deformation of the inner and outer curved panels 22, 72 by the weight of the concrete poured into the space 5 between the inner and outer formwork walls 1, 6.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 depicts a formwork for casting a concrete annular section for a pre-stressed concrete tower.

[0010] FIG. 2 shows the show a detail of the formwork.

[0011] FIG. 3 depicts front view of the formwork.

[0012] FIG. 4 shows a detail of the inner wall of the formwork.

[0013] FIG. 5 depicts an upper view of an assembled formwork.

[0014] FIG. 6 shows un upper view of the formwork when concrete has been poured into the space defined within the formwork.

[0015] FIG. 7 depicts a casted concrete annular section.

[0016] FIG. 8 and FIG. 9 depict the demolding of the as well as the removal of segment to reduce the size of the formwork.

[0017] Fig. 13A- 13B show the joining means for joining the inner and the outer walls of the formwork [0018] FIG. 1 1A to l lG depict the upper view of a number of inner formwork wall of formworks to cast tapered annular sections of a pres- stressed concrete tower.

[0019] FIG. 12 depicts a climbing formwork according to the invention.

[0020] FIG. 13 depicts stepped tower sections casted with the formwork of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0021] With reference to FIG. 1 the Formwork A of the present invention is comprised of an Inner formwork wall ( 1) and an Outer formwork wall (6) defining a gap or formwork cavity (5) between the inner ( 1) and outer (6) walls of the formwork. A concrete sludge is subsequently is poured into the formwork cavity and casted when the concrete solidifies.

[0022] The tower built under the present invention is of a triangular cross-section. The tower is disclosed in W02009056969A2, accordingly, the tower has a triangular cross-section having three rounded walls and three trapezoidal wall adjacent to said rounded walls. The rounded wall remain of constant width along the height of the tower but the width of the trapezoidal wall it is reduced uniformly along the height of the tower. As result, the tower is tapered.

[0023] According to the present invention, the inner formwork wall 1 comprises an (a) inner flat section 10, and (b) an inner curved section 20, both sections being alternated. The inner flat section 10 is composed of multiples inner rectangular panels - and two inner trapezoidal panel 15. As can be seen in figures 1 to 4, the inner rectangular panels 12 are arranged adjacent one to other, as slabs, and at each end (right and left ends) there are placed respective trapezoidal panels 15. This way the arrangement of rectangular panels 12 and trapezoidal panels 15 conform a flat trapezoidal wall. [0024] The inner curved sections 20, each consist of a curved panel

22 made in one piece, in turn joined at both sides, right and left, to the trapezoidal panels 15 of the inner flat section 10. The surface of the inner panel 22 forms a curved section of 60°.

[0025] In a preferred embodiment of the invention, depicted in the drawings, each panel, it is to say, the rectangular panels 12, the trapezoidal panels 15 and the inner curved panel 22, include an edge flange 17 along the perimeter of such panels. The edge flanges 17 reinforce the panels and prevent that the assembled formwork can be deformed by the weight of the concrete verted or poured onto the formwork cavity. In addition, the edge flanges provide a surface by which adjacent panels can be joined through the use of joining means 40 of inner panels, for example, the joining means 40 consist of clamps. In other embodiment the joining means 40 are bolts which pass through orifices (not shown) provided in the edge flanges of two adjacent panels and then, engage a respective nut.

[0026] The inner curved section 20 of the formwork of the present invention is made in one steel sheet to prevent deviations that alter the symmetry and precision of the tower to be erected.

[0027] As can be seen in figures, the inner curved panels 22 also include ribs 27, said ribs are intended to prevent the deformation of the inner curved section 20 of the inner formwork wall. The inner formwork wall 1 is also reinforced with a support 30 of the inner wall, said inner support 30 consist of a support 32 of the inner flat section and a support 35 of the inner curved section. Said inner support 30 prevents the deformation of the walls toward the center of the formwork. The formworks of the present invention are reinforced by the ribs 27 and the support 35.

[0028] As can be seen in figures 1, 2, 4 and 5, the support 35 of the inner curved section is a structure of beans (horizontal beams 36, vertical beams 37 and diagonal beams 38) assembled to distribute the charges generated by the weight of the concrete when this is poured into the formwork. [0029] The reinforcement ribs 27 and the support 35 are intended to prevent the deformation of the inner wall 1 of the formwork A, which integrity must be maintained despite the fact the formwork is repeatedly used.

[0030] In an additional embodiment (not shown), the support 32 of the inner flat section also include a structure of beans for the same purposes.

[0031] To assemble the formwork, there is optionally disposed an inner template 51, on which the panels are leant before joining the panel through the joining means 40.

[0032] The outer formwork wall 6 has a similar structure than the inner formwork wall 1, but it is constructed using wider panels. The outer formwork wall 6 comprises an (a) outer flat section 60, and (b) an outer curved section 70, both sections being alternated. The outer flat section 60 is composed of multiples outer rectangular panels 62 and two outer trapezoidal panel 65. As can be seen in figures 1 to 4, the outer rectangular panels are arranged adjacent one to other, as slabs, and at each end (right and left ends) there are placed respective outer trapezoidal panels 65. This way the arrangement of rectangular panels and trapezoidal panels conform a flat trapezoidal wall.

[0033] The outer curved sections 70, consist of a curved panel 72 made in one piece, in turn joined at both sides, right and left, to the trapezoidal panels 65 of the outer flat section 60. The surface of the inner panel 62 forms a curved section of 60°.

[0034] In a preferred embodiment of the invention, depicted in the drawings, each panel, it is to say, the rectangular panels 62, the trapezoidal panels 65 and the outer curved panel 72, include an edge flange 67 along the perimeter of such panels. The edge flanges 67 reinforce the panels of the flat section and prevent that the assembled formwork can be deformed by the weight of the concrete verted or poured onto the formwork cavity. In addition, the edge flanges 67 provide a surface by which adjacent panels can be joined through the use of joining means 92 (Figure 3) of outer panels, for example, the joining means consist of clamps. In other embodiment the joining means 90 are bolts which pass through orifices (not shown) provided in the edge flanges of two adjacent panels and then, engage a respective nut.

[0035] The outer curved panel 72 of the formwork of the present invention is preferably made in one steel sheet to prevent deviations that alter the symmetry and precision of the tower to be erected.

[0036] As can be seen in figures, the outer curved panel 72 also include ribs 77, said ribs are intended to prevent the deformation of the outer curved section 70 of the outer formwork wall 6. The outer formwork wall 6 is also reinforced with a support 80 of the outer wall, said outer support 80 consist of a support 82 of the outer flat section and a support 85 of the outer curved section. Said outer support 80 prevents the deformation of the walls outside the center of the formwork. The formworks of the present invention are reinforced by the ribs 77 and the support 85.

[0037] As can be seen in figure 3, the support 85 of the outer curved section is a structure of beans (horizontal beams 86, vertical beams 87 and diagonal beams 88) assembled to distribute the charges generated by the weight of the concrete when this is poured into the formwork.

[0038] The reinforcement ribs 77 and the support 85 are intended to prevent the deformation of the outer wall 6 of the formwork A, which integrity must be maintained despite the fact the formwork is repeatedly used.

[0039] In an additional embodiment (not shown), the support 82 of the outer flat section also include a structure of beans for the same purposes.

[0040] The reinforcement support 30, 80, of the respective inner and outer curved sections 20, 70 is critical for the performance of the formwork of the present invention. Such support 30, 80 prevent any deformation of the inner and outer curved sections of the formwork. The deformation of the curved sections results in the casting of a deformed concrete section which result in an appropriate assemble of the subsequent tower section formworks, which in turn result in a deformed non-vertical, leant, tower structure.

[0041] To assemble the formwork, there is optionally disposed an outer template 56, on which the panels are leant before joining the panels through the joining means 90.

[0042] As depicted in Figure 10A and 10B the inner and outer formwork walls are joined through formwork walls joining means 100, for example a plurality of ties 1 1 placed between the inner and outer panels of the inner and outer formwork walls. The ties firmly space the inner and outer walls of the formwork and prevent the formwork can deform and the width of the wall may vary. The ties are well known in the art, they can be recoverable ties or non-recoverable ties, depending whether or not the ties remain embedded within the casted concrete. The ties 101 are introduced in respective holes on the respective inner 1 and outer 6 walls extending along the width of the space 5 between walls and respectively secured to the panels (flat and curved) of the inner and outer formwork walls. As shown in Figures 10A and 10B the ties comprise a bar 104 which has threaded ends where wing nuts are placed on. The ties 101 also comprise setting cones 105 to fix a position that prevent the walls bring closer whilst the nuts prevent the walls separate. The wing nut 102 may conveniently comprise a washer 107 and the ties 101 may comprise a bracket 106.

[0043] Once a concrete section of the annular tower has been casted, the formwork is removed, for doing so it is preferred to remove a trapezoidal panel 15 of the inner formwork wall 1 and 65 of the outer formwork wall 2, as it is depicted in figure 7, wherein the outer formwork wall has been removed. [0044] Once the formwork is removed, then an inner rectangular panel 12 of each wall is removed and the flat panels adjacent to the rectangular panel 12 and joined together in the way shown in figure 8 and

9.

[0045] By removing one panel from each inner and outer flat sections, the basically same formwork is used in the manufacture of the subsequent sections of the tower, which have a shorter width than the precedent section casted. Figures 1 1A to 1 1G show an upper view of the inner formwork. The number of rectangular panels in each section is shown in the below table.

[0046] The lower section is a defined triangular cross-section, and the upper section is of a circular cross-section. A cylindrical metallic or concrete extension is connected to the upper section via a connector or flange.

[0047] In Figure 12 it is shown an embodiment of the invention wherein the formwork is a climbing formwork, the sections are casted on the previous one after adjusting the formwork by removing the rectangular flat inner and outer panels 12 and 62.

[0048] In an embodiment of the invention, both templates 51 and 56 may include a step to construct an stepped section of concrete, such stepped section is depicted in Figure 13.

[0049] The concrete is poured and casted within the space (5) there are placed structural rigid steel roads, arranged in a way well known for a person skilled in the art, such structural rigid road are designed to be embedded within the concrete when it solidifies. In addition, in the space are also placed ducts for introducing pre-stressing means, such as pre stressing cables, roads or tendons.

[0050] The invention being thus described may be varied in many ways for a person skilled in the art. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are considered to be included within the scope of the following claims.

A Formwork

1 Inner formwork wall

5 Space between walls

6 Outer formwork wall

8 Concrete

9 Concrete annular section

10 inner flat section of the inner formwork wall

12 inner rectangular panel of the inner flat section

15 inner trapezoidal panel of the inner flat section

17 edge flange

20 inner curved section of the inner formwork wall

22 inner curved panel of the inner curved section

27 ribs of the inner curved section

30 support of the inner wall

32 support of the inner flat section 35 support of the inner curved section

36 horizontal beam

37 vertical beam

38 diagonal beam

joining means of inner panels

42 joining means of inner flat panels

45 joining means of inner curved panels

inner template

outer template

ears for lifting

outer flat section of the outer formwork wall

62 outer rectangular panel of the outer flat section

65 outer trapezoidal panel of the outer flat section

67 edge flange

outer curved section of the outer formwork wall 72 outer panels of the outer curved section

77 supporting ribs of the outer curved section support of the outer wall

82 support of the outer flat section

85 support of the outer curved section

86 horizontal beam

87 vertical beam

88 diagonal beam

joining means of outer panels

92 joining means of outer flat panels

95 joining means of outer curved panels

formwork walls joining means

tie

wing nut

threaded bar

seating cone

bracket

washer