U.S. patent application number 14/701782 was filed with the patent office on 2015-09-10 for tower construction and a method for erecting the tower construction.
This patent application is currently assigned to CONELTO APS. The applicant listed for this patent is CONELTO APS. Invention is credited to Jorgen Hangel.
Application Number | 20150252580 14/701782 |
Document ID | / |
Family ID | 44318682 |
Filed Date | 2015-09-10 |
United States Patent
Application |
20150252580 |
Kind Code |
A1 |
Hangel; Jorgen |
September 10, 2015 |
Tower Construction and a Method for Erecting the Tower
Construction
Abstract
A tower construction with a foundation and a top and a lower
force distribution element in the foundation and an upper force
distribution element at the top. Between the upper and lower force
elements there are provided prefabricated concrete tower elements
and at least one interlinking element. Tower elements and at least
one interlinking element placed on top of the foundation form a
column. Tendons and interlinking tendons are fastened such that the
tendons span from the upper to the lower force distribution
element, and the interlinking tendons span only over sections of
the tower, the sections comprising the interlinking element at one
end and another element at the opposite end, wherein the other
element is the upper force distribution element, the lower force
distribution element, or an additional interlinking element. The
interlinking element is hollow and with a thickened circumferential
segment inside to which the interlinking tendons are fastened.
Inventors: |
Hangel; Jorgen; (Vejle O,
DK) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CONELTO APS |
Give |
|
DK |
|
|
Assignee: |
CONELTO APS
Give
DK
|
Family ID: |
44318682 |
Appl. No.: |
14/701782 |
Filed: |
May 1, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13576455 |
Aug 23, 2012 |
9021757 |
|
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14701782 |
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Current U.S.
Class: |
52/223.5 ;
52/745.18 |
Current CPC
Class: |
E04B 2103/02 20130101;
F03D 13/20 20160501; Y02P 70/50 20151101; F03D 13/10 20160501; E04H
12/12 20130101; Y02E 10/72 20130101; E04H 12/342 20130101; E04C
1/39 20130101; E04C 5/08 20130101; Y02E 10/728 20130101; F05B
2230/60 20130101; B66C 1/66 20130101; E04H 12/16 20130101 |
International
Class: |
E04H 12/16 20060101
E04H012/16; E04H 12/34 20060101 E04H012/34; E04H 12/12 20060101
E04H012/12; E04C 5/08 20060101 E04C005/08; E04C 1/39 20060101
E04C001/39 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 1, 2010 |
DK |
PA 2010 70030 |
Jun 22, 2010 |
DK |
PA 2010 70284 |
Claims
1-22. (canceled)
23. A tower construction comprising a foundation and a top and a
lower force distribution element in the foundation and an upper
force distribution element at the top; wherein between the upper
and lower force elements there are provided prefabricated concrete
tower elements and at least one interlinking element, one on top of
the other; the tower elements and the least one interlinking
element each having an outside, an inside, a material thickness
provided there between, top and bottom surfaces, and a hollow
centre; the tower construction further comprising a plurality of
tendons, each tendon connected to the upper force distribution
element and to the lower force distribution element by co-operating
attachment means, each tendon tensioned for applying a tension
force to the column between the upper force element and the lower
force element; the tower construction further comprising a
plurality of interlinking tendons of which each interlinking tendon
is connected to the interlinking element and to another element
selected among the upper force distribution element, the lower
force distribution element or an additional interlinking element;
each interlinking tendon spanning less than the length of the tower
from the upper force element to the lower force element and being
tensioned for applying a tension force only to a section of the
tower construction, the section extending from the interlinking
element to the selected element.
24. A tower construction according to claim 23, wherein the section
comprising the interlinking element at one end of the section and
the other element at the other end of the section and at least one
tower element therein between, and wherein the interlinking tendons
are not fastened to the tower elements.
25. A tower construction according to claim 23, wherein the
interlinking element is formed as a hollow tube with a tubular axis
and a tubular outside wall between the top and bottom surfaces, the
outside wall comprising a thickened circumferential segment on its
inside between the top and bottom surfaces and at a distance from
the top surface and from the bottom surface, the thickened segment
being provided with an increased thickness as compared to the
thickness of the outside wall between the thickened segment and the
top and bottom surfaces; wherein holes extend through the thickened
segment in a direction parallel with the tubular axis, wherein the
interlinking tendons extend through the holes and are fastened to
the thickened segment.
26. A tower construction according to claim 23, wherein the
interlinking element comprises protrusions extending in parallel
with the tubular axis between the top surface and the bottom
surface and wherein the protrusions comprise a hollow bore
longitudinally through the protrusions; and wherein the tendons but
not the interlinking tendons extend through the hollow bore.
27. A tower construction according to claim 26, wherein the tower
element comprises protrusions extending in parallel with the
tubular axis between the top surface and the bottom surface and
wherein the protrusions comprise a hollow bore longitudinally
through the protrusions; and wherein the protrusions of the tower
elements are arranged in extension of the protrusion of the
interlinking element; and wherein tendons but not the interlinking
tendons extend through the hollow bore of the protrusions of the
tower element as well as through the protrusions of the
interlinking element.
28. A tower construction according to claim 23, wherein the
interlinking element comprises a tubular inside wall that is
provided inside and concentric with the tubular outside wall and
connected thereto by a plurality of webs extending parallel with
the tubular axis.
29. A tower construction according to claim 28, wherein an elevator
is provided inside the inside wall, the inside wall forming an
elevator shaft.
30. A tower construction according to claim 23, wherein the
interlinking element comprising at least one aperture through the
outside wall dimensioned for feeding the interlinking tendons
through the aperture from the outside to the inside.
31. A tower construction according to claim 23, wherein the
interlinking element is connected to the upper force distribution
element or to the lower force distribution.
32. A tower construction according to claim 23, wherein the
interlinking element is connected to the upper force distribution
element with first interlinking tendons and connected to the lower
force distribution element with second, different interlinking
tendons.
33. An interlinking element for a tower construction according to
claim 23, the interlinking element being formed as a hollow tube
with a tubular axis and comprising top and bottom surfaces at
opposite ends and a tubular outside wall between the top and bottom
surfaces, the outside wall having an outside, an inside, and a
material thickness provided there between; the outside wall
comprising a thickened circumferential segment on its inside
between the top and bottom surfaces and at a distance from the top
surface and from the bottom surface, the thickened segment being
provided with an increased thickness as compared to the thickness
of the outside wall between the thickened segment and the top and
bottom surfaces; wherein holes extend through the thickened segment
in a direction parallel with the tubular axis, the holes being
configured as attachment means for first ends of interlinking
tendons extending through the holes.
34. The interlinking element of claim 33, further comprising
protrusions extending in parallel with the tubular axis between the
top surface and the bottom surface and wherein the protrusions
comprise a hollow bore longitudinally through the protrusions
configured for tendons extending through the hollow bore.
35. The interlinking element of claim 33, further comprising a
tubular inside wall that is provided inside and concentric with the
tubular outside wall and connected thereto by a plurality of webs
extending parallel with the tubular axis.
36. The Interlinking element according to claim 33, further
comprising at least one aperture through the outside wall
dimensioned for feeding the interlinking tendons through the
apertures from the outside to the inside.
37. A method for erecting a tower construction according to claim
23, the method involving the following steps: establishing a
foundation with the lower force distribution element, providing a
plurality of prefabricated concrete tower elements and at least one
interlinking element, each having an outside, an inside, a material
thickness provided there between, top and bottom surfaces, and a
hollow centre; the interlinking element having first attachment
means adapted for co-operation with second attachment means on
first ends of interlinking tendons; forming a column by arranging
tower elements and interlinking elements on top of each, with at
least one tower element adjacent to each interlinking element,
until the final height of the column is reached with an upper force
distribution element at the top; providing a plurality of tendons
and a plurality of interlinking tendons, connecting each tendon to
the upper force distribution element and to the lower force
distribution element by co-operating attachment means, and
tensioning each tendon for applying a tension force to the column
between the upper force element end the lower force element;
connecting a group of a plurality of interlinking tendons to one of
the at least one interlinking element and to another element
selected among the upper force distribution element, the lower
force distribution element or an additional interlinking element;
and tensioning each interlinking tendon in the group for only
applying a stabilising tension force with this group in a section
of the tower construction, the section extending from the
interlinking element to the selected element with each tendon in
the group spanning less than the length of the tower from the upper
to the lower force distribution element.
38. A method according to claim 37, wherein the method comprises
completing the section and tensioned the tensioning the
interlinking tendons in the group before the erection of the tower
is complete.
39. A method according to claim 37, wherein the section comprises
the interlinking element at one end of the section and the other
element at the other end of the section and at least one tower
element therein between, and wherein the interlinking tendons run
through the at least one tower element and are fastened to the
interlinking element and the other element but not to the at least
one tower element.
40. A method according to claim 39, wherein the method comprises
dividing the tower into a plurality of sections, wherein: a) one
section comprises the upper force element, a tower section and an
interlinking element; or b) one section comprises the upper force
element, a tower section and an interlinking element; or both a)
and b) and where the interlinking tendons of the section with the
upper force elements are different from the interlinking tendons of
the section with the lower force element.
41. A method according to claim 37, wherein the interlinking
element is formed as a hollow tube with a tubular axis and a
tubular outside wall between the top and bottom surfaces, the
outside wall comprising a thickened circumferential segment on its
inside between the top and bottom surfaces and at a distance from
the top surface and from the bottom surface, the thickened segment
being provided with an increased thickness as compared to the
thickness of the outside wall between the thickened segment and the
top and bottom surfaces; wherein holes extend through the thickened
segment in a direction parallel with the tubular axis, wherein the
method comprises feeding interlinking tendons through the holes and
fastening the interlinking tendons to the thickened segment.
42. A method according to claim 37, wherein the interlinking
element is provided with at least one aperture through the outside
wall and wherein the method comprises feeding the interlinking
tendons through the apertures from the outside to the inside.
43. A method according to claim 37, wherein the interlinking
element is provided with at least one aperture through the outside
wall and wherein the method during erection of the tower
construction comprises feeding anchor cables through the apertures
from the outside to the inside and fastening these anchor cables to
the interlinking element.
Description
[0001] This application is a division of Ser. No. 13/576,455 filed
Aug. 23, 2012 which claims the benefit of Danish Application No. PA
2010 70030 filed Feb. 1, 2010, Danish Application No. PA 2010 70284
filed Jun. 22, 2010 and PCT/DK2011/050022 filed Jan. 31, 2011,
International Publication Number WO 2011/091799, which are hereby
incorporated by reference in their entireties as if fully set forth
herein.
FIELD OF THE INVENTION
[0002] The present invention relates to a concrete tower
construction comprising; a foundation, a plurality of prefabricated
concrete tower elements each comprising an outside wall having a
hollow centre, said tower elements arranged in a column on top of
the foundation and a plurality of tendons arranged in the hollow
centre or within the material thickness, for applying a tension
force to the column
[0003] The present invention furthermore relates to a method for
erecting a tower construction.
[0004] The present invention also relates to a concrete tower
element having an outside, an inside, a material thickness provided
there between, and top and bottom surfaces, said tower element
having a hollow centre.
[0005] Furthermore the invention also relates to a concrete
foundation element having an outside, an inside, a material
thickness provided there between, and top and bottom surfaces, said
foundation element having a hollow centre.
[0006] Even further the invention relates to an interlinking
element.
BACKGROUND OF THE INVENTION
[0007] Towers for wind turbines have preferably been made of steel
by the wind turbine industry for the past 30 years. Development of
the industry has been towards larger wind turbines with rotors of
increasing diameter. This has required the wind turbine tower to
increase in height.
[0008] The cost of wind turbine towers has therefore increase over
the past years, and especially the logistics of transporting the
steel sections comprising the wind turbine towers have proved to be
a challenge. Usually the towers have been transported in sections
of up to 30 meters. The towers now approach a height of 100 meters
and more. Therefore the tower may comprise four or more
sections.
[0009] Steel reinforced concrete towers, which were introduced in
the 1930s, have recently gained favour again for tower heights of
more than 80 meters. For concrete towers there are two main
options: site-mixed concrete or prefabricated concrete towers.
[0010] Site-mixed concrete towers have some disadvantages, for
example the difficulty in controlling the quality of the concrete
and the logistics in transporting the concrete mixture to the site.
Site-mixed concrete towers will not be discussed any further.
[0011] Prefabricated concrete towers may be manufactured at a
central location. The process of mixing concrete and setting the
concrete may be controlled in such a way as to produce concrete
elements with relatively low manufacturing tolerances. The material
will be uniform, and hence the strength of the prefabricated
concrete elements will be uniform.
[0012] With prefabricated concrete towers, the transportation
disadvantages of the steel towers are overcome. Size of the
concrete elements composing the tower is selected such that they
allow road or rail transport.
[0013] A method of fabricating a prefabricated concrete tower is
based on segments prefabricated in a central manufacturing site.
The segments are produced using conventional manufacturing
techniques. When the sections have set, they are transported to the
site and placed on top of each other and bonded together. The
towers are provided with longitudinal tubes in the wall of each
segment evenly distributed along their circumference for inserting
tendons, which are tensioned when the assembly is complete. The
concrete tower is pre-stressed such that the tower is in tension
during all operational conditions of the wind turbine.
[0014] An example of such tower is known from WO 02/01025. The
disadvantage of the tower described in WO 02/01025 is that the
tendons are not accessible for inspection.
[0015] This has been solved in EP 1 262 614 which describes a tower
construction comprising a foundation, a plurality of annular
sections placed on top of each other and with a steel tower placed
on top of the concrete part of the tower construction. The tower
construction has tendons spanning the length of the tower
construction. The steel tower placed on top of the concrete section
comprises attachments means for one end of the tendons. The other
end of the tendons terminates inside a space in the foundation. The
tendons are pre stressed against the concrete foundation by a
hydraulic jack and wedged against the concrete by an anchoring
element.
[0016] Although the system described in EP 1 262 614 may be
successfully implemented, the system has some disadvantages.
[0017] In a tower of considerable height, for example towers
exceeding 80 meters, the pre-stressing of the tendons will apply
very high local forces in the foundation where the anchor elements
are abutting the foundation. Therefore, the foundation needs to be
oversized in order to be able to take up the forces without
cracking or the number of tendons need to increase, which in turn,
requires the diameter of the tower to increase to accommodate the
increased number of tendons.
[0018] It is another disadvantage that the tower segments may be
difficult to position along the centreline of the tower such that
the tower is straight.
OBJECT OF THE INVENTION
[0019] The object of the present invention is to provide an
improved concrete tower construction.
DESCRIPTION OF THE INVENTION
[0020] According to the present invention, this objective is
achieved by a concrete tower construction comprising; a foundation,
a plurality of prefabricated concrete tower elements each
comprising an outside wall having an outside, an inside, a material
thickness provided there between, and top and bottom surfaces, said
tower element having a hollow centre, said tower elements arranged
in a column on top of the foundation and a plurality of tendons
arranged in the hollow centre or within the material thickness, for
applying a tension force to the column, wherein the tower
construction further comprises an upper force distribution element
arranged on top of the column and a lower force distribution
element arranged in the foundation, wherein each tendon is
connected to the upper force distribution element and the lower
force distribution element by co-operating attachment means, and
that the foundation includes at least one prefabricated concrete
foundation element comprising an outside wall having an outside, an
inside, a material thickness provided there between, and top and
bottom surfaces, said foundation element having a hollow centre,
said at least one foundation element is arranged between the column
and the lower force distribution element, for forming a foundation
column below the surface of the ground.
[0021] Furthermore this objective is achieved by a method for
erecting a tower construction comprising the following steps:
a. establishing the foundation having a lower force distribution
element, b. providing a plurality of prefabricated concrete tower
elements, each having an outside, an inside, a material thickness
provided there between, and top and bottom surfaces, said tower
element having a hollow centre, c. forming a column by arranging
one tower element on top of another until the final height of the
column is reached, d. providing a plurality of tendons, e.
connecting each tendon to the upper force distribution element and
the lower force distribution element by co-operating attachment
means, and f. tensioning each tendon for applying a tension force
to the column.
[0022] Furthermore this objective is achieved by a concrete tower
element having an outside, an inside, a material thickness provided
there between, and top and bottom surfaces, said tower element
having a hollow centre, wherein the tower element includes a
plurality of protrusions extending into the hollow centre, wherein
the protrusions has a hollow bore, said hollow bore extend parallel
to the longitudinal axis of the tower element.
[0023] Furthermore this is also achieved by a concrete foundation
element having an outside, an inside, a material thickness provided
there between, and top and bottom surfaces, said foundation element
having a hollow centre, wherein the foundation element includes a
plurality of attachment means on the outside, and wherein each
attachment means is arranged for attachment to a rebar or rebar
cage.
[0024] Furthermore this is also achieved by an interlinking element
comprising an outside wall having an outside, an inside, a material
thickness provided there between, and top and bottom surfaces, said
interlinking element having a hollow centre, wherein the
interlinking element has attachment means, wherein the attachment
means are adapted for co-operation with attachment means on an
interlinking tendon.
[0025] With a tower construction according to the invention an
improvement of the transfer of forces between the tendons and the
concrete tower elements is achieved. The tension force which is
transferred from the tendons to the concrete is efficiently
distributed to the concrete elements in a way that avoids the
introduction of local stress concentrations exceeding the yield
stress of concrete, and thereby avoiding fracturing of the
concrete.
[0026] The pre-tensioning of each tendon may thereby reach a higher
value with the more effective utilisation of the strength of the
tendons. This allows for the construction of taller towers having
fewer tendons allowing for a smaller diameter tower.
[0027] With the method according to the invention an improvement of
the transfer of forces between the tendons and the concrete tower
elements is achieved.
[0028] With the concrete tower element according to the invention
an improvement is achieved, wherein the tower element is easy to
locate and orientate.
[0029] With the concrete foundation element according to the
invention an improvement is achieved, wherein the foundation
element may comprise a higher strength material compared to an
in-situ cast reinforced concrete foundation.
[0030] The foundation for the tower construction may be in-situ
cast or constructed of a plurality of prefabricated foundation
elements.
[0031] A foundation composed of prefabricated foundation elements
may be manufactured in a controlled environment providing improved
material properties and allowing for tighter geometrical
tolerances.
[0032] A foundation composed of prefabricated foundation elements
may be positioned in an excavation for the foundation. A rebar cage
may be established around the foundation elements and an in-situ
cast concrete foundation is established around the prefabricated
elements. The rebar cage is connected to the attachment means on
the outside of the foundation elements.
[0033] Said at least one prefabricated foundation elements will
form a foundation column below the surface of the ground and
embedded into in-situ cast reinforced concrete. The tower elements
are forming a tower column above the surface and on top of the
foundation column. Upon tensioning of the tendons the tower
elements and the said at least one foundation element are
effectively forming a single structural element which is embedded
into the foundation.
[0034] It is herewith achieved that the bending forces of the tower
is primarily transferred through surface friction between the
foundation elements and the in-situ cast concrete.
[0035] In the prior art of steel towers on a concrete foundation,
the bending forces are transferred through a bottom flange of the
tower to the foundation. In EP 1 262 614 the bending forces and the
tension forces applied by the tendons is reacted through the bottom
surface of the lower most tower element to the foundation. Both
construction methods cause comparably large local stresses.
Therefore the towers are conical to provide a larger surface for
reacting the bending force to the foundation.
[0036] In an alternative embodiment the foundation elements and the
tower elements are identical.
[0037] The prefabricated concrete tower elements may also be
manufactured in a controlled environment for providing improved
mechanical properties of the material and tighter geometrical
tolerances.
[0038] The concrete used for the tower elements and optionally the
pre-cast foundation elements may be a high-strength concrete, for
example compact reinforced composite (CRC), where ductility is
achieved through incorporation of a large content of short, stiff
and strong fibres. The strength of compact reinforced composite is
about 150-400 MPa. Recent material development has increased the
strength of the high-strength concrete to approach 800 Mpa.
[0039] The tower elements are placed on top of the foundation and
arranged in a column comprising the number of tower elements
necessary to reach the desired height of the tower
construction.
[0040] The hollow centre, apart from housing the tendons, may also
house a stairway or elevator to provide access to the top of the
tower. The stairway may also be used during inspection of the
tendons.
[0041] The tendons may also be arranged within the material
thickness of the tower elements and/or foundation elements, said
elements having hollow bores to accommodate the tendons. The
tendons may hereby be isolated form environmental influences having
a degrading effect on the life of the tendons, the tendons may
still be inspected by for example applying a tension force to the
tendon and measure the elongation.
[0042] When the desired height of the column has been reached, the
tendons are tensioned. The tension ensures that the column, and
hence the tower elements, always will be in compression, even
though the tower is subject to bending forces. This is because the
compressive strength of concrete is much higher than the bending
strength.
[0043] The tendons are connected to the force distribution elements
by co-operating attachments means.
[0044] The term "connected to" designate any means to transfer
force from the tendons to the force distribution elements. For
example abutment, welding, clamping or any other means of
mechanically transferring the force from the tendon to the force
distribution element.
[0045] The lower force distribution element is arranged in the
foundation. A space sufficient to provide access to installing and
tensioning the attachment means is provided at the lower force
distribution element.
[0046] The arrangement of the lower force distribution element may
be by casting the lower force distribution element into the
concrete foundation or by providing a support surface on the
concrete foundation. The lower force distribution element is
preferably of a high strength material, for example carbon
composite, steel, titanium or other material with a high yield
strength and ductility.
[0047] In a preferred embodiment the tower construction is peculiar
in that the lower force distribution element is a reinforced high
strength concrete casting. For example the reinforcement may be
metal, composite or plastics.
[0048] The upper force distribution element is located on top of
the upper most tower element. The upper force distribution element
may be attached to the upper most tower element or held in loose
abutment by friction when the tendons are tensioned.
[0049] Alternatively the upper force distribution element may be
integrated into the top tower element.
[0050] The upper force distribution element is preferably of a high
strength material, for example carbon composite, steel, titanium or
other material with a high yield strength and ductility.
[0051] In a preferred embodiment the tower construction is peculiar
in that the upper force distribution element is a reinforced high
strength concrete casting. For example the reinforcement may be
metal, composite or plastics.
[0052] A shim may be arranged between adjacent tower elements or on
the top and bottom surfaces of every other tower element. The
purpose of the shim is to even out any surface irregularities
between adjacent elements. The shim may also provide friction
between adjacent elements such that relative rotation between
elements due to torsion is avoided. The shim may be solid,
semi-solid or liquid upon application.
[0053] For example the shim material may be epoxy binder. Epoxy is
liquid upon application and will even out any surface
irregularities between adjacent elements and on the same time
provide a significant friction between elements. Another example of
a shim material may be neoprene, which will even out any surface
irregularities between adjacent elements. Neoprene may also provide
the necessary friction between adjacent elements to avoid relative
rotation of the elements.
[0054] In a further embodiment according to the invention, the
tower construction is peculiar in that the upper force distribution
element and/or the lower force distribution element is an annulus,
wherein the annulus has a free portion for attachment of the
tendons.
[0055] It is herewith achieved to provide a simple means of
distributing the force across the top surface of the uppermost
tower element and/or distributing the force across the abutment
surface between the lower force distribution element and the
foundation.
[0056] The tendons may be attached to the free portion of the force
distribution element. The free portion may be overlapping the
hollow centre of the tower elements or provided by a recess on the
inside of the tower element below the upper force distribution
element next to each tendon allowing the tendon to be attached to
the force distributing element above the material thickness of the
tower elements.
[0057] It is preferred that the attachment point of the tendon to
the force distribution element is as close to the inside of the
tower elements as possible.
[0058] Alternatively a recess is provided on the inside of the
tower element or foundation above the lower force distribution
element next to each tendon allowing the tendon to be attached to
the force distributing element below the material thickness of the
tower elements.
[0059] In a further embodiment the tower construction according to
the invention is peculiar in that the tower elements is a cylinder
or a frustum, having an upper wide end and a lower narrow end or a
combination of said cylinder and frustum.
[0060] With cylindrical tower elements it is achieved that the
casting of the tower elements is simplified. Furthermore, the
strengths properties of the cylinder are symmetrical in all
directions. Therefore the tower construction is especially suited
for use in installations where the loads are changing and coming
from different directions.
[0061] With tower elements as a frustum it is achieved that the
lifting of the tower elements is achieved in a simple manner. The
lifting equipment may clamp on the outside of the tower element
which has an increasing size towards the top. The lifting equipment
is capable of lifting the tower elements without adding excessive
clamping forces. The same is achieved with a tower element having
one cylindrical portion and one frustum shaped portion.
[0062] In a further embodiment the tower construction according to
the invention is peculiar in that the tower elements includes a
plurality of protrusions extending into the hollow centre, wherein
the protrusions has a hollow bore, said hollow bore extend parallel
to the longitudinal axis of the tower construction.
[0063] A tendon is run through the protrusions and may therefore be
guided during the erection of the tower construction. The
protrusion may be embedded in the pre cast tower element or
attached to the tower element after setting of the concrete or be a
bracket attached on the inside of the tower element.
[0064] The protrusions may be evenly distributed on the inside
surface or be unevenly distributed to give way for attachment of
other equipment to the inside surface of the tower elements for
example a stairway. Each tendon or only a sub set of the tendons
may run through protrusions.
[0065] In a further embodiment the tower constructions according to
the invention is peculiar in that the protrusions extend between
the top and bottom surfaces of the tower elements. It is herewith
achieved that the protrusions may add to the surface area of the
tower elements. Thus the protrusions are able to transfer forces
between the tower elements.
[0066] In a preferred embodiment the tower construction according
to the invention is peculiar in that the tower elements have at
least six or more preferably evenly incrementing number of
protrusions evenly distributed along its inner periphery.
[0067] During erection of the tower construction this is
advantageous because at least six tendons may run through the tower
construction during the entire erection process being guided by the
protrusions. The tendons will guide the tower elements in place
such that it becomes easy to orient and precisely locate the tower
elements on top of each other.
[0068] Three of the tendons for example every other tendon may be
tensioned during the erection of the tower construction, using
non-permanent attachment means for example wedges to be inserted
between the tendons and the bore of the protrusions. The tower
elements will be held together in compression by the tensioned
tendons so that the structural integrity of the tower is ensured
during the erection. When an additional tower element is placed in
the column the three tendons that are free may be guided through
the protrusions of the additional tower elements, tensioned to
place the tower in compression, where after the previously
tensioned tendons are released and run through the remaining
protrusions of the additional tower elements, where after the next
additional tower element may be introduced to the column and
secured by the free tendons.
[0069] All tendons may also be tensioned during the erection of the
tower, so that the compression forces are more evenly distributed.
Upon adding a tower element to the column the tension forces in one
tendon is relieved. The tendon is fed through the added tower
element. Tension is applied to the tendon for securing the tower
element. The process is repeated with the next tendon until all
tendons have been secured to the added tower element. The sequence
in which the tendons are fed through the added element is such that
the next tendon is selected as far from the previous tendon in a
cross pattern.
[0070] The tendons may be inspected after installation by removal
and reinstallation. Alternatively the total number of tendons may
be selected such that the tendons outside the protrusions provide
sufficient tension force after the tower has been installed.
[0071] In an even more preferred embodiment the number of
protrusions is eight. Providing an even better distribution of
compression forces when the tower is erected.
[0072] The interlinking element allows for the tower to be
sectionalised. The sections may be compressed individually. The
interlinking tendons will provide the primary compression force in
each section. As the interlinking tendons are not spanning the
entire length of the tower the elongation of each interlinking
tendon when it is tensioned is less than the elongation of the
tendons which span the entire length of the tower.
[0073] Furthermore the size of the tower elements and the number of
interlinking tendons may taper towards the top of the tower
lowering the overall weight of the tower.
[0074] In a further embodiment the tower construction according to
the invention is peculiar in that wherein adjacent tower elements
has corresponding conical top and bottom surfaces. It is herewith
achieved that the tower elements may centre more easily due to the
conical shape of the top surface of one tower element and bottom
surface of an adjacent tower element.
[0075] The angle of the conical surface is preferably larger than
0.degree. and less than 10.degree.. It is important that the angle
is not too high to avoid the transfer of shear forces between tower
elements.
[0076] In a further embodiment the tower construction according to
the invention is peculiar in that the tower construction further
comprises a top tower element, wherein said top tower element is
attached to the top of the column with co-operating fastening means
and wherein the top tower element has additional fastening means
arranged for installation of a wind turbine nacelle.
[0077] It is herewith achieved that a wind turbine nacelle may be
connected to the tower construction. The top tower element acts an
adapter between the tower construction and the wind turbine
nacelle. The top tower element may be made of steel. The additional
fastening means may be the yaw mechanism attached to the top of the
top tower element and the bottom of the wind turbine nacelle.
[0078] In a further embodiment the tower construction according to
the invention is peculiar in that said tower construction further
comprises at least one interlinking element comprising an outside
wall having an outside, an inside, a material thickness provided
there between, and top and bottom surfaces, said interlinking
element having a hollow centre, said at least one interlinking
element is arranged between the lower and the upper force
distribution elements, and said tower construction further
comprises a plurality of interlinking tendons, wherein each
interlinking tendon is arranged in the hollow centre of the
interlinking element, wherein the interlinking element end the
interlinking tendon has co-operating attachment means, and wherein
each interlinking tendon at one end is attached to an interlinking
element, and at the other end to the upper force distribution
element or the lower force distribution element or a further
interlinking element.
[0079] It is herewith achieved that the column of the tower
construction may be sectionalised. The boundaries of each section
are at one end an interlinking element and at the other end the
upper or the lower force distribution elements or an additional
interlinking element. The sections include the tower elements and
where applicable foundation elements. In the following description
a section including the lower force distribution element may
include foundation elements and/or tower elements. However the
foundation elements and the tower elements will be regarded as
equivalents.
[0080] A tower with two sections will have one interlinking element
arranged between the upper and the lower force distribution element
with interlinking tendons spanning between the interlinking element
and the force distribution elements, thus only spanning part of the
column height.
[0081] A tower with more than two sections will have at least one
section, which has an interlinking element at either end.
Interlinking tendons connects the interlinking elements.
[0082] The column has a plurality of tendons connected to the upper
and the lower force distribution elements, as these tendons are
used for stabilising the column during construction of the
tower.
[0083] The interlinking element and the interlinking tendons has
co-operating attachment means as well as the interlinking tendons
and the lower and upper force distribution elements.
[0084] The tower elements in one section may be different than a
tower element in another section.
[0085] Tower elements closer to the bottom of the tower need to be
stronger than tower elements closer to the top of the tower. A
strong tower element will have a high weight compared to a less
strong tower element. When the tower is sectionalised the tower
elements in each section may be identical and optimized for the
highest load condition in that particular section. Furthermore the
number of interlinking tendons applying compression forces to a
section may differ from section to section throughout the tower
construction depending on the compression force needed in each
section.
[0086] In the lower most section of the tower, the tower
elements/foundation elements may be strong, heavy and have a high
number of interlinking tendons. The tower elements in sections
above the lower most section of the tower will have tower elements,
with a gradually decreasing strength, weight and number of
interlinking tendons. It is herewith achieved that the weight of
the tower is decreased especially closer to the top of the tower,
which in it self will lower the strength requirement of the lower
most tower elements.
[0087] The length of each section in a tower construction is a
trade-off between the number of different tower elements and the
strength/weight optimisation. For manufacturing purposes the
preferred number of different tower elements is small and
preferably all tower elements are identical, but for
strength/weight optimisation the preferred number of different
tower elements is high and preferably all tower elements are
different.
[0088] It is therefore necessary to apply engineering analysis to
establish the most cost effective number of different tower
elements. The sections may be of uneven length or identical length
dependent on the strength distribution along the height of the
tower.
[0089] For example the lower most sections may have a shorter
length than sections closer to the top of the tower, because the
weight of the lower most sections are higher and therefore the gain
of changing to a new size tower element is higher.
[0090] The interlinking element may be cast concrete, cast
high-strength concrete, fibre reinforced composites, or a suitable
metallic material. Interlinking elements composed of concrete may
be provided with a rebar cage.
[0091] The geometry of each interlinking element is such that it
may be arranged between to tower elements of a non-identical or
identical size. Typically no two interlinking elements may be
identical throughout one tower construction. However, the
construction may allow for two or more identical interlinking
elements. If the tower elements comprise protrusion with through
going tendons the interlinking elements will have corresponding
protrusions to take up the tendons.
[0092] In an alternative embodiment of the tower construction the
lower and/or the upper force distribution element is identical to
the interlinking element.
[0093] In a further embodiment the tower construction according to
the invention is peculiar in that the tower elements further
comprises an inside wall arranged inside the hollow centre and
having an outside and an inside and a material thickness provided
there between, wherein the inside wall is connected to the outside
wall by a plurality of webs.
[0094] It is herewith achieved that the moment of inertia and
therefore the strength of a given tower element is increased
significantly for a comparatively small weight increase.
[0095] The tendons and interlinking tendons, if applicable, is
arranged between the outside wall and the inside wall.
[0096] An elevator may be provided within the inside wall. A cavity
within the inside wall will act as an elevator shaft. Reinforced
openings in the inside wall is provided near the bottom of the
tower. The elevator may also be accessed from below the lower force
distribution element. Further openings may be provided along the
length of the shaft to allow access to the area between the outside
and inside wall for inspection of the tendons and the interlinking
tendons.
[0097] The webs may also have an opening to allow access to all
interlinking tendons. The opening in the webs, subject to the
stresses in the webs, may also be provided to lighten the tower
construction.
[0098] The elevator shaft will terminate near the top of the tower
to allow access to the top of the tower and any installations here,
for example the nacelle of a wind turbine.
[0099] In a further embodiment the tower construction according to
the invention is peculiar in that the foundation element further
comprise an inside wall arranged inside the hollow centre and
having an outside and an inside and a material thickness provided
there between, wherein the inside wall is connected to the outside
wall by a plurality of webs.
[0100] As for the tower element with an inside wall the inside wall
of the foundation element may be used as an elevator shaft. The
elevator shaft may thereby start below the lower force distribution
element.
[0101] It is preferred that reinforced openings in the inside wall
is provided in the foundation element to allow for access to the
area between the outside and inside wall, such that the tendons and
the interlinking tendons may be accessed and serviced.
[0102] The webs may also have an opening to allow access to all
interlinking tendons. The opening in the webs, subject to the
stresses in the webs, may also be provided to lighten the tower
construction.
[0103] In a further embodiment the tower construction according to
the invention is peculiar in that the interlinking element further
comprise an inside wall arranged inside the hollow centre and
having an outside and an inside and a material thickness provided
there between, wherein the inside wall is connected to the outside
wall by a plurality of webs.
[0104] It is herewith achieved that the moment of inertia and
therefore the strength of a given interlinking element is increased
significantly for a comparatively small weight increase.
[0105] As for the tower element with an inside wall the inside wall
of the interlinking element may be used as an elevator shaft. The
elevator shaft may thereby span across multiple tower sections.
[0106] It is preferred that reinforced openings in the inside wall
is provided in the interlinking element to allow for access to the
area between the outside and inside wall, such that the attachment
means of the interlinking tendons may be accessed and serviced.
[0107] The webs may also have an opening to allow access to all
interlinking tendons. The opening in the webs, subject to the
stresses in the webs, may also be provided to lighten the tower
construction.
[0108] In an alternative embodiment the tower construction
according to the invention is peculiar in that additional tendons
is provided within the inside wall of the tower elements, the
foundation elements and the interlinking elements as applicable.
The lower and upper force distribution elements are provided with
attachment means which cooperates with attachment means on the
additional tendons.
[0109] It is herewith achieved that the compression forces may be
increased.
[0110] In a further embodiment the tower construction according to
the invention is peculiar in that the tower construction further
comprises at least one anchor flange, said anchor flange being
arranged between two adjacent tower elements, and a plurality of
anchor cables, said plurality of anchor cables being evenly
distributed around the perimeter of the anchor flange, and each
anchor cable being connected to the anchor flange at one end and
being adapted for connection to a ballast arranged on the ground at
the other end.
[0111] It is herewith achieved that the tower construction may be
further stabilised. The anchor cables, which are connected to the
tower construction via the anchor flange, are connected to a
ballast or other anchoring means on the ground. The ballast or
anchoring means is sized to prevent oscillations exceeding a set
amplitude of the tower construction.
[0112] In a preferred embodiment the tower construction is peculiar
in that the interlink element is configured with means for
attachment to anchor cables, which are adapted for being attached
to a ballast, for stabilising the tower construction.
[0113] A method of erecting a tower construction according to the
invention is described in the following:
[0114] The foundation is established by excavating an area to the
necessary depth.
[0115] One method of establishing the foundation is in-situ
casting. For an in-situ cast foundation the shuttering and steel
reinforcement is established. The lower force distribution element
is positioned and levelled out as necessary and held in place
during the casting of the foundation.
[0116] Another method of establishing the foundation is by
prefabricated concrete foundation elements. If the tower foundation
is established of prefabricated hollow foundation elements a first
element may be positioned to support the lower force distribution
element that is positioned and levelled out. Thereafter further
prefabricated hollow foundation elements may be located on top of
the lower force distribution element until the first tower element
is placed on top of the upper most foundation element.
[0117] The foundation element that supports the lower force
distribution element may have one shape and the foundation elements
placed on top of the lower force distribution element may have
another shape.
[0118] Commonly for the two methods are that the foundation has a
hollow centre for accommodating the tendons, a space or cellar
below the lower force distribution element providing access to
installing and tensioning the tendons and an access path to the
cellar and inside of the tower from the outside.
[0119] A first method of forming the column of tower elements on
top of the foundation is described below.
[0120] The tower elements are placed in continuation of each other
in a horizontal orientation or on top of another with the tower in
a vertical orientation for forming a column
[0121] The top and bottom surfaces of the tower elements may be
prepared for contact by adding a suitable bonding material or a
gasket to even out any surface roughness.
[0122] The column is positioned in a vertical orientation on top of
the foundation using lifting equipment. The tendons are installed
either before or after the column is placed on top of the
foundation. The tendons are connected to the force distribution
elements and tensioned as necessary to achieve the required
compression forces in the tower construction.
[0123] A second method of forming the column of tower elements on
top of the foundation is described below.
[0124] When said first tower element is located on top of the
foundation the upper force distribution element is located on top
of that element. The first tower element is secured for lifting
using suitable lifting equipment.
[0125] The first tower element is then lifted to a sufficient
height allowing a second tower element to be located on top of the
foundation below the first tower element.
[0126] The top and bottom surfaces of the tower elements may be
prepared for contact by adding a suitable bonding material or a
gasket to even out any surface roughness.
[0127] When the top and bottom surfaces are prepared the first
tower element is lowered onto the second tower element and the
column is starting to form.
[0128] The now two tower elements are secured for lifting. Then the
two tower elements forming a column is lifted to a sufficient
height for allowing an additional tower element to be placed on top
of the foundation and the column is lowered on to that additional
tower element in a similar manner as for the first two tower
elements. These steps are repeated while the column is continuously
secured for lifting by the lifting equipment and possibly
additional wires connected to ground anchors.
[0129] When the final height of the column is reached the tendons
are run through the length of the column The tendons are connected
to the upper force distribution element and the lower force
distribution element by cooperation attachment means. Alternatively
the tendons are installed concurrent with the erection of the tower
construction.
[0130] Then each tendon is tensioned following a predefined pattern
for ensuring a symmetrical compression of the tower
construction.
[0131] The advantage of the second method, wherein the tower is
assembled in this bottom-up approach, is that the lifting equipment
does not have to be able reach above the centre of mass of the
tower. In both the first and second method the lifting equipment
needs at least to be able to support the full weight of the tower
column.
[0132] The column may be secured by tethers attached to the column
in a symmetrical configuration for centring the column above the
foundation. The tethers when tensioned apply a downwards force to
the column that the lifting equipment also needs to overcome.
[0133] In a further aspect the method for erecting a tower
construction according to the invention is peculiar in that step of
forming a column further comprises: [0134] dividing the tower into
sections by providing at least one interlinking element for each
section, [0135] inserting an interlinking element replacing a tower
element at the end of each section during assembly, [0136]
providing a plurality of interlinking tendons, [0137] connecting
each interlinking tendon at one end of the section to the
interlinking element and at the other end of the section to an
element selected among the upper force distribution element, the
lower force distribution element or an additional interlinking
element, and [0138] tensioning each interlinking tendon for
applying a tension force to the section.
[0139] It is herewith achieved that the tower may be divided into
sections, which enable optimisation of the tower elements with
regards to strength and weight within each section. Each section is
pre-tensioned upon completion and before the next section is
begun.
[0140] A sectionalised tower construction according to the method
above may be erected as follows:
[0141] Upon establishing the foundation having a lower force
distribution element, the column is beginning to form by placing
the upper force distribution element on top of the first tower
element and positioning the two elements on top of the foundation.
The two elements are secured to each other and lifted such that an
additional tower element may be positioned between the column and
the foundation. The column is lowered to make contact with the
additional tower element. The additional tower element is connected
to the column and the column is lifted again. These steps are
repeated until the length of the first section of the column is
complete. An interlinking element is replacing the additional tower
element and connected to the column. A plurality of interlinking
tendons is connected between the interlinking element and the upper
force distribution element. The interlinking tendons are tensioned
in a pattern as to avoid twisting of the section. The section is
then completely pre-tensioned before the erection of the tower is
complete.
[0142] During the erection process the tower may be stabilised and
secured by connecting anchor wires to an interlinking element or an
anchor flange. Each anchor wire may be connected to a winch with an
auto torque function. The winch will have a set torque and during
lifting of a section by using the lifting equipment the winch will
automatically unwind during lifting. There will be at least three,
preferably four anchor wires and associated winches evenly
distributed around the tower. The winches will the automatically be
able to stabilise the tower during lifting.
[0143] The column now comprises the first section. Lifting the
column begins the next section. A tower element is positioned below
the column and above the foundation. The tower element may be
different from the tower elements in the first section. Additional
tower elements are added to the column as before until the desired
length of the second section is reached.
[0144] The tower elements within a section may be identical or
different to each other.
[0145] The section may terminate by inserting an additional
interlinking element at the end of the section replacing a tower
element. Interlinking tendons are connected between the
interlinking element and the additional interlinking element and
tensioned.
[0146] The above steps of forming sections are repeated until prior
to terminating the last section. Connecting and tensioning
interlinking tendons between the interlinking element of the last
but one section and the lower force distribution element terminate
the last section.
[0147] A tower construction with only two sections only has one
interlinking element. A tower construction with more than two
sections has one interlinking element less than the total number of
sections.
[0148] The tower elements, foundation elements and interlinking
elements of the sectionalised tower construction may have a
plurality of protrusions extending into the hollow centre, wherein
the protrusions has a hollow bore, said hollow bore extend parallel
to the longitudinal axis of the tower construction. A tendon is
provided through each protrusion spanning the height of the tower.
These tendons are primarily used during erection of the tower
construction. The protrusions and tendons are of an even number of
more than six, preferably eight. During erection of the tower the
column is continuously in compression by at least three, preferably
four tendons. This increases the safety during the erection of the
tower construction as the elements in the column are held firmly
together at all times.
[0149] The interlinking element may be provided with at least one
aperture in the outside wall. The purpose of the aperture is to
allow the interlinking tendons to be fed through the wall of the
interlinking element.
[0150] It is herewith achieved that it is avoided to feed in the
interlinking tendons from the top of the tower or from the bottom
of the tower.
[0151] The tower construction may be land based or adapted for
offshore installation.
[0152] In offshore installations the foundation comprising the
lower force distribution element and foundation elements is
established at the surface. The foundation is thereafter lowered a
short distance towards the sea bottom. The tower elements are
thereafter attached one by one on top of the foundation. The partly
assembled tower construction is gradually lowered until the tower
construction is high enough to span the distance from the sea floor
to the sea surface. Hereafter the tower construction above the sea
surface is erected using a conventional method similar to what is
used in land based installations.
[0153] Alternatively the tower may be constructed in sections. Each
section is positioned and connected to a previous section.
[0154] During the offshore installation the tower may be further
stabilised using cables connected between the tower construction
and ballasts on the sea floor.
DESCRIPTION OF THE DRAWING
[0155] The invention will be explained in more detail below with
reference to the accompanying drawing, where:
[0156] FIG. 1 shows an isometric section view of a tower
construction according to the invention,
[0157] FIG. 2 shows an exploded view a first embodiment of two
tower elements of the tower construction according to FIG. 1,
[0158] FIG. 3 shows a cross sectional side view of a foundation of
the tower construction according to FIG. 1,
[0159] FIG. 4 shows a cross sectional side view of a foundation of
the tower construction according to an alternative embodiment,
[0160] FIG. 5 shows a cross sectional side view of the upper part
of the tower construction according to FIG. 1,
[0161] FIG. 6a shows a cross section of a first embodiment of a
tower element,
[0162] FIG. 6b shows a section view of a tower element along A-A of
FIG. 6a,
[0163] FIG. 7a shows a cross section of a second embodiment of a
tower element,
[0164] FIG. 7b shows a section view of a tower element along A-A of
FIG. 7a,
[0165] FIG. 8 shows an isometric section view of a third embodiment
of a tower element,
[0166] FIG. 9 shows a plan view of a tower element according to
FIG. 8,
[0167] FIG. 10 shows an isometric section view of a fourth
embodiment of a tower element,
[0168] FIG. 11 shows a plan view of a tower element according to
FIG. 10,
[0169] FIG. 12 shows an isometric section view of a fifth
embodiment of a tower element,
[0170] FIG. 13 shows a plan view of a tower element according to
FIG. 12,
[0171] FIG. 14 shows an isometric section view of a sixth
embodiment of a tower element,
[0172] FIG. 15 shows a plan view of a tower element according to
FIG. 14,
[0173] FIG. 16 shows a plan view of a first embodiment of a
lower/upper force distribution element,
[0174] FIG. 17 shows an isometric section view of a first
embodiment of an interlinking element,
[0175] FIG. 18 shows an isometric section view of a seventh
embodiment of a tower element,
[0176] FIG. 19 shows an isometric section view of a second
embodiment of an interlinking element,
[0177] FIG. 20 shows a cross section view of an interlinking
element according to FIG. 19,
[0178] FIG. 21 shows a principle of a sectionalised tower
construction,
[0179] FIG. 22 shows a detail section cut of the tower construction
in an embodiment comprising an anchor flange,
[0180] FIG. 23 shows an exploded view an eighth embodiment of two
tower elements of the tower construction,
[0181] FIG. 24 shows an isometric section view of a eighth
embodiment of a tower element, and
[0182] FIG. 25 shows a plan view of a tower element according to
FIG. 24.
DETAILED DESCRIPTION OF THE INVENTION
[0183] In the explanation of the figures, identical or
corresponding elements will be provided with the same designations
in different figures. Therefore, no explanation of all details will
be given in connection with each single figure/embodiment.
[0184] FIG. 1 shows an isometric section view of a concrete tower
construction 10 comprising a foundation 12 below ground level 14.
The foundation 12 comprises a prefabricated support element 16 as
the lower most foundation element. The support element 16 may be
fabricated in concrete. A lower force distribution element 18 is
arranged on top of the support element 16. In the embodiment shown
in FIGS. 1, 3, and 4 three pre-fabricated foundation elements 20
are located on top of the lower force distribution element 18. The
foundation 12 further comprises and in-situ cast portion around the
support element 16, the lower force distribution element 18 and the
foundation elements 20. The in-situ cast portion is not shown on
the FIG. 1 for clarity.
[0185] In alternative embodiments the foundation may include one or
more support elements and second foundation elements. The number of
foundation elements is determined by a number of factors for
example the dimensions of the tower construction, static and
dynamic forces applied by a load on the tower, wind loads, and the
weight and dimensions of the foundation and foundation
elements.
[0186] The lower and the upper force distribution elements 18, 26
are both an annulus with a free portion partly overlapping the
hollow centre of the column 22.
[0187] A column 22 comprising a plurality of prefabricated concrete
tower elements 24 is located in abutment with the upper most
foundation element 20. An upper force distribution element 26 is
arranged on top of the column 22.
[0188] The foundation elements 20 and the tower elements 24 have a
hollow centre, wherein a plurality of tendons 28 is arranged. Each
tendon 28 is connected to the upper force distribution element 26
at one end and to the lower force distribution element 18 by
co-operating attachment means 30, 30' (only four tendons is shown
on FIG. 1 for clarity). The attachment means 30' at the lower force
distribution element 18 includes means for tensioning the tendons
28. The means for tensioning may be a nut engaging a thread on the
tendons 28, or any other suitable means of applying tension and
transferring the tension force from the tendons 28 to the lower
force distribution element 18.
[0189] The tendons 28 may also be arranged within the material
thickness 36 between the outside 32, an inside 34 of the hollow
tower elements 24.
[0190] The support element 16 have an internal space for providing
access to the attachment means 30'.
[0191] In the embodiment shown on FIG. 1 the foundation elements 20
are identical to the tower elements.
[0192] In an alternative embodiment the foundation 12 is an in-situ
cast tower foundation.
[0193] A top tower element 31 is arranged on top of the column 22.
The top tower element 31 is attached to the column 22 by
co-operating fastening means (not shown). The top tower element 31
has additional fastening means (not shown) arranged for
installation of a wind turbine nacelle (not shown).
[0194] FIG. 2 shows an exploded view of two tower elements 24 of
the tower construction 10 according to FIG. 1. The tower elements
24 each having an outside 32, an inside 34, a material thickness 36
provided there between, and top 38 and bottom surfaces 40, said
tower element 24 having a hollow centre, said tower elements 24 are
arranged one tower element 24' on top of another 24'' forming a
column 22 (se FIG. 1) on top of the foundation 12 (see FIG. 1).
[0195] The tower element has a cylindrical portion 42 and a frustum
portion 44. The frustum portion 44 has its wide end above its
narrow, such that the diameter is increasing towards the top of the
tower element 24. The frustum portion 44 is adapted for
co-corporation with lifting equipment (not shown), which will clamp
onto the frustum portion 44 during lifting of the tower elements
24.
[0196] A plurality of tendons 28 is running through the hollow
centre of the tower elements 24 close to the inside 34.
[0197] The tower elements 24 include a plurality of protrusions 46.
The protrusions 46 are extending between the top 38 and bottom 40
surfaces. Each protrusion 46 has a hollow bore that is parallel
with a longitudinal axis through the tower element 24 and hence the
tower construction 10 (see FIG. 1). A tendon 28 is running through
each protrusion 46 for assisting the alignment of the tower
elements 24 during assembly of the column 22.
[0198] FIG. 3 shows a cross sectional side view of a foundation 12
of the tower construction 10 according to FIG. 1. The support
element 16 has an access opening 48 for providing access for
service and maintenance personnel to the inside of the tower
construction 10. The access is hereby provided without influencing
the structural integrity of the tower construction 10.
[0199] The access opening 48 is connected to a plurality of
prefabricated access shaft elements 50', 50''. The shaft elements
50'' provides and opening 52 at ground level 14.
[0200] FIG. 4 shows a cross sectional side view of a foundation 12
of the tower construction 10 according to an alternative
embodiment. The support element 16 has an access opening 48 for
providing access for service and maintenance personnel to the
inside of the tower construction 10. The access is hereby provided
without influencing the structural integrity of the tower
construction 10.
[0201] The access opening 48 is connected to a plurality of
prefabricated access shaft elements 50', 50''. The shaft elements
50'' provides and opening 52 at ground level 14.
[0202] A conventional access door 54 is provided in a tower element
24. This door 54 and the associated structural discontinuity has
structural impact on the structural integrity of the tower
construction 10. The tower element 24 therefore needs to be
reinforced by introducing a reinforced frame 55 around the door
opening. The frame 55 may have attachment for the tendons 28 in the
top and bottom for transferring the tension forces.
[0203] FIG. 5 shows a cross sectional side view of the upper part
of the tower construction according to FIG. 1. A top tower element
31 is arranged on top of the column 22. The top tower element 31 is
attached to the column 22 by co-operating fastening means (not
shown). The top tower element 31 has additional fastening means
(not shown) arranged for installation of a wind turbine nacelle
(not shown).
[0204] The top tower element 31 comprise attachment means 56 for
attachment of a tether (not) shown to control the column 22 during
lifting
[0205] FIG. 6a shows a cross section of a first embodiment of a
tower element 24 and FIG. 6b shows a section view of the tower
element 24 along A-A of FIG. 6a.
[0206] In the embodiment shown in FIGS. 6a and 6b the tower element
24 has five protrusions 46 that are evenly distributed around the
inside 34 of the tower element 24.
[0207] The tower element 24 has conical top 38 and bottom 40
surfaces. The conical surfaces are arranged such that a bottom
surface 40 on one tower element 24 corresponds to a top surface on
an adjacent tower element 24. The inclination of the conical
surfaces is larger than 0.degree. and less than 10.degree. to limit
the shear forces, while achieving acceptable self-centring
capabilities of the tower elements 24.
[0208] FIGS. 6a and 6b apply to the foundation element in
embodiments of the foundation element that is identical with a
tower element.
[0209] FIG. 7a shows a cross section of a second embodiment of a
tower element 24 and FIG. 7b shows a section view of the tower
element 24 along A-A of FIG. 7a.
[0210] In the embodiment shown in FIGS. 7a and 7b the tower element
24 has six protrusions 46 that are evenly distributed around the
inside 34 of the tower element 24.
[0211] FIGS. 7a and 7b apply to the foundation element in
embodiments of the foundation element that is identical with a
tower element.
[0212] The tower element 24 has conical top 38 and bottom 40
surfaces. The conical surfaces are arranged such that a bottom
surface 40 on one tower element 24 corresponds to a top surface on
an adjacent tower element 24. The inclination of the conical
surfaces is larger than 0.degree. and less than 10.degree. to limit
the shear forces, while achieving acceptable self-centring
capabilities of the tower elements 24.
[0213] FIGS. 8 and 9, 10 and 11, 12 and 13, 14 and 15 shows an
isometric section view and a plan view respectively of a third,
fourth, fifth and sixth embodiment of a tower element 24. Each
embodiment in FIGS. 8 to 15 is adapted for a section of a tower
construction 10 comprising four sections.
[0214] The third embodiment shown in FIGS. 8 and 9 is adapted for
the first section, which is the lowermost section. The first
section is located on top of the lower force distribution element
18 (see FIG. 1). Some of the foundation elements 20 (see FIG. 1)
may be identical to this third embodiment of the tower element
24.
[0215] The fourth embodiment shown in FIGS. 10 and 11 is adapted
for the second section, which is located on top of the first
section,
[0216] The fifth embodiment shown in FIGS. 12 and 13 is adapted for
the third section, which is located on top of the second
section.
[0217] The sixth embodiment shown in FIGS. 14 and 15 is adapted for
the fourth section, which is located on top of the third section.
The upper force distribution element 26 (see FIG. 1) is located on
top of the fourth section.
[0218] The material thickness 36 of the tower elements 24 is
decreasing from the third embodiment, which is the thickest tower
element 24 to the sixth embodiment, which is the thinnest tower
element 24.
[0219] Each tower element 24 in FIGS. 8 to 15 comprises an outside
wall 58 having an outside 32, an inside 34, a material thickness 36
provided there between, and top 38 and bottom surfaces 40, said
tower element 24 having a hollow centre, said tower elements 24 are
arranged one tower element 24' on top of another 24'' forming a
column 22 (se FIG. 1) on top of the foundation 12 (see FIG. 1).
[0220] A plurality of interlinking tendons 60 is running through
the hollow centre of the tower elements 24 close to the inside
34.
[0221] The tower elements 24 include a plurality of protrusions 46.
The protrusions 46 are extending between the top 38 and bottom 40
surfaces. Each protrusion 46 has a hollow bore that is parallel
with a longitudinal axis through the tower element 24 and hence the
tower construction 10 (see FIG. 1). A tendon 28 is running through
each protrusion 46 for assisting the alignment of the tower
elements 24 during assembly of the column 22 and for providing
compression of the column 22 during erection of the tower
construction 10.
[0222] The tendons 28 and the interlinking tendons 60 are arranged
close to the inside 34 of the tower elements 24 of the fourth
section, which is the upper most section. It is herewith achieved
that the upper force distribution element 26 is supported by the
structure of the upper most tower element 24 as close to the
attachment point of the tendons 28 and the interlinking tendons 60.
The radial bending moments in the upper force distribution element
26 is thereby limited as much as possible.
[0223] As the material thickness 36 of the tower elements 24 is
increasing towards the lower sections the inside 34 of the tower
elements 24 is provided with furrows 62 making room for the tendons
28 and the interlinking tendons 60. This arrangement will increase
the area supporting the lower force distribution element 18, and
thereby reduce the bending moments in the lower force distribution
element 18. The third and fourth embodiment is equipped with
furrows 62.
[0224] FIG. 16 shows a plan view of a first embodiment of a
lower/upper force distribution element 18, 26. The lower/upper
force distribution element 18, 26 is an annulus with evenly
distributed openings 64 for the tendons 28 and the interlinking
tendons 60. The first embodiment comprises forty openings 64.
[0225] FIG. 17 shows an isometric section view of a first
embodiment of an interlinking element 66. The interlinking element
66 comprises an outside wall 58' having an outside 32', an inside
34', a material thickness 36' provided there between, and top 38'
and bottom surfaces 40', said interlinking element 66 having a
hollow centre, said interlinking element 66 is adapted for being
arranged between to adjacent tower elements 24.
[0226] The interlinking element 66 is provided with a
circumferential attachment arrangement 68. Said attachment
arrangement 68 having co-operating fastening means for attachment
of interlinking tendons 60 (see FIG. 8-15).
[0227] The interlinking element 66 is having protrusions 46' which
correspond to the protrusions on the tower elements 24 (see FIG.
8-15). The protrusions 46' have a hollow bore for running through
the tendons 28, such that the tendons 28 may run uninterrupted from
the upper force distribution element 26 (see FIG. 1) to the lower
force distribution element 18 (see FIG. 1).
[0228] FIG. 18 shows an isometric section view of a seventh
embodiment of a tower element 24. This embodiment comprise an
inside wall 70 arranged inside the hollow centre and having an
outside 72 and an inside 74 and a material thickness 76 provided
there between, wherein the inside wall 70 is connected to the
outside wall 58 by a plurality of webs 78.
[0229] Hollow bores 82 are provided for the tendons 28 and cavities
84 are provided for the interlinking tendons 60. The number of
hollow bores and cavities are defined by engineering analysis.
[0230] The centre of the inside wall 70 may be used as an elevator
shaft.
[0231] The foundation elements may be identical to this seventh
embodiment of the tower element.
[0232] FIG. 19 shows an isometric section view and FIG. 20 shows a
cross section view of a second embodiment of an interlinking
element 66. This embodiment comprise an inside wall 70' arranged
inside the hollow centre and having an outside 72' and an inside
74' and a material thickness 76' provided there between, wherein
the inside wall 70' is connected to the outside wall 58' by a
plurality of webs 78'.
[0233] Hollow bores 82' are provided for the tendons 28' and
cavities 84' are provided for the interlinking tendons 60'.
[0234] The centre of the inside wall 70' may be used as an elevator
shaft.
[0235] Each cavity 84' of the interlinking element 66 is provided
with an aperture 86 for providing access for feeding an
interlinking tendon 60 through the outside wall 80' to the cavity
84'.
[0236] The aperture 86 is directed downwards towards the outside of
the interlinking element 66. This is mainly because the
interlinking tendons 60 are fed from below, but also because rain
water and condensation will tend to run towards the outside of the
interlinking element 66.
[0237] Anchor cables (not shown) may be fed through the apertures
86 during erection of the tower construction for stabilising the
tower during lifting. The anchor cables (not shown) may be attached
to the interlinking element 66 by for example a wedge or other
suitable attachment means. The anchor cable (not shown) adapted for
connection to a ballast (not shown) arranged on the ground.
[0238] The number of anchor cables 92 is at least three for
providing even stability to the tower construction 10.
[0239] Each attachment means 90 may be connected to more than one
anchor cable. For example two or three anchor cables 92.
[0240] The interlinking element 66 is provided with a
circumferential attachment arrangement 68. Said attachment
arrangement 68 having co-operating fastening means for attachment
of interlinking tendons 60 (see FIG. 8-15).
[0241] As seen on FIG. 20 the attachment arrangement 68 for the
interlinking tendons 60 comprise a plurality of through holes 80.
Interlinking tendons 60 from above the interlinking element 66 is
run through every other through hole 80 and attached to the
attachment arrangement 68 on the bottom side of the attachment
arrangement 68 by co-operating attachment means, for examples a
wedge arrangement or any other suitable commercially available
attachment means.
[0242] Interlinking tendons from below the interlinking element 66
is run through the remaining through holes 80 and attached to the
attachment arrangement 68 on the top side of the attachment
arrangement 68 by co-operating attachment means, for examples a
wedge arrangement or any other suitable commercially available
attachment means.
[0243] The embodiment shown on FIG. 20 has eighty through holes 80.
Therefore forty interlinking tendons 60 may be connected to either
side of the interlinking element 66. The number of interlinking
tendons 60 may taper towards the top of the tower. The number of
through holes 80 may also taper towards the top of the tower or
alternatively remain unused.
[0244] FIG. 21 shows a principle of a sectionalised tower
construction 10. The tower construction comprises two sections. The
tower comprises from bottom to top a lower force distribution
element 18, a tower element 24/foundation element 20, an
interlinking element 66, a tower element 24 and an upper force
distribution element 26.
[0245] The person skilled in the art will based on FIG. 21 be able
to add more elements to construct a taller column 22. The tower
construction 10 will in practise have more tower elements 24 in the
upper most section and more tower elements 24/foundation elements
20 in the lower most section.
[0246] The lower force distribution element 18 and/or the upper
force distribution element 26 are identical to the interlinking
element 66 but for the lower/upper half respectively.
[0247] The tendons 28 are spanning the complete height of the
column 22 and the interlinking tendons 60 are only spanning part of
that height.
[0248] Anchor cables 92, which are adapted for being attached to a
ballast on the ground is connected to the interlinking element
66.
[0249] FIG. 22 shows a detail section cut of the tower construction
10 in an embodiment comprising an anchor flange 88. The anchor
flange 88 is arranged between two adjacent tower elements 24, 24'.
The anchor flange 88 has attachment means 90 for an anchor cable
92. The anchor flange 88 has a plurality of attachment means 90
evenly distributed around the perimeter of the anchor flange 88. An
anchor cable 92 is connected to each attachment means 90 at one end
and being adapted for connection to a ballast (not shown) arranged
on the ground at the other end.
[0250] The number of anchor cables 92 is at least three for
providing even stability to the tower construction 10.
[0251] Each attachment means 90 may be connected to more than one
anchor cable. For example two or three anchor cables 92.
[0252] FIG. 23 shows an exploded view an eighth embodiment of two
tower elements 24 of the tower construction 10. The tower elements
24 each having an outside 32, an inside 34, a material thickness 36
provided there between, and top 38 and bottom surfaces 40, said
tower element 24 having a hollow centre, said tower elements 24 are
arranged one tower element 24' on top of another 24'' forming a
column 22 (se FIG. 1) on top of the foundation 12 (see FIG. 1).
[0253] A plurality of hollow bores 94 are provided in the material
thickness 36 of the tower elements 24 between the outside 32 and
the inside 34. The hollow bores 94 are parallel with the
longitudinal axis through the tower element 24 and hence the tower
construction 10 (see FIG. 1).
[0254] A plurality of tendons 28 is running through the hollow
bores 94.
[0255] FIG. 24 shows an isometric section view and FIG. 25 shows a
plan view of the eighth embodiment of a tower element 24.
[0256] On FIG. 24 the section is cutting through two of the hollow
bores 94. FIG. 24 shows the orientation of the hollow bore 94 along
the longitudinal axis of the tower element 24.
[0257] On FIG. 25 the distribution of the hollow bores 94 can be
seen. The hollow bores 94 are distributed evenly in a symmetric
pattern around the tower element 24. In alternative embodiments the
hollow bores 94 may differ in size and they may be distributed in a
non-symmetrical pattern.
* * * * *