Note: Descriptions are shown in the official language in which they were submitted.
MOUNTING ASSEMBLY AND METHOD TO ERECT IN SECTIONS
AN ANNULAR TOWER FOR WIND OR HELIOSTATIC POWER
GENERATORS IN AN ENERGY FARM
Field of the invention
This invention refers to a mounting assembly and method for assembling at
floor level segmented sections of an annular pre-stressed concrete tower,
particularly a mounting assembly to form tower sections from concrete tower
segments to erect an annular tower for wind or heliostatic power generators
and its method of erection.
Description of the related art
International patent application WO-2003069099 (& US-7,160, 085 and EP-
1 474 579) assigned to MECAL describe a hybrid tower for wind power
generators, which includes: (a) a lower part of an annular sectioned (tower
divided in sections) and segmented (sections divided in segments) made of
pre-stressed concrete and (b) an upper one consisting of a metallic tubular
body connected to a power generator.
US Patent US 7,765,766 describes a pre-stressed concrete annular tower
and erecting method which uses a perforated assembly base. The concrete
tower segments include a lower protruding metallic bars which are
introduced in the perforated assembly base so the concrete tower segments
form a tower section which is in turn horizontally pre-stressed; and the
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concrete tower segments also include upper perforations so corresponding
lower protruding metallic bars of superjacent segments can be introduced in.
Such perforated assembly bases do not provide a safety support for
assembling the concrete tower segments. In addition, incorporating
protruding metallic bars increases the cost of the concrete towers. In order
to assemble every section it is necessary to provide perforated assembly
base with the diameter of the section to be assembled.
The construction of pre-stressed concrete use pre-stress tendons generally
constituted of cables or rods of high resistance steel, to provide a
compression load that reinforces the concrete structure.
The methods for assembling of the prior art have as main drawback the
provision of a safety structure for assembling. It is necessary to say that
segments of 12 meters height and of several tons of weight can be easily
mounted at to floor level; nevertheless, the mounting operation at 30 meters
height it is difficult under a windy environment it is risky. The sections
must
be mounted with the needed precision. Insofar as the prior art does not
provide a process for assembling that can be conducted in a safety way and
with the suitable precision. In addition, often, the unions must be cemented,
which increases the complexity of the construction. In addition, the concrete
tower segments are made using different molds and the segments could
probably not coincide.
International patent application WO/2010/067166 of the same inventors of
the present application describes a process to mount in sections an annular
concrete tower. That process requires a mounting assembly unit for every
section of the tower of a certain diameter. In addition, the mounting assembly
and the concrete section are both hoisted together to erect the tower, so the
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time lapse in which the concrete section is mounted to erect the tower cannot
take advantage to assemble new sections.
The mounting assembly of the invention and the method for assembling can
also raise towers for heliostatics applications, and for the erection of any
class of annular tower, post or chimney. The mounting assembly and the
method of assembly of the present invention provide a better functionality
when compared with the assembly methods of the prior art.
SUMMARY OF THE INVENTION
It is therefore, an object of the present invention to provide one mounting
assembly for concrete tower segments to form sections of an annular tower
of pre-stressed concrete for wind or heliostatic power generators.
Another object of the invention is to provide a method for assembling at floor
level, concrete section from concrete tower segments of an annular tapered
pre-stressed concrete tower of pre-stressed concrete for wind or heliostatic
power generators with the use of a mounting assembly, where the mounting
assembly is adjustable to the different dimensions of the sections to be
assemble andeach segment conforming a section of the tower is placed in
the exact required position and tilt.
To solve these previous objects, the present invention provides a process
for assembling in sections an annular pre-stressed concrete tower
comprising:
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1. providing a tower foundation and a plurality of concrete tower
segments;
2. providing a mounting assembly for assembling the sections of the
tower at floor level, the mounting assembly comprising:
a. a mounting base comprising three pairs of radially extended
double parallel arms;
b. a slippable support at a distal point from a center of the base
that slips on the pair of double parallel arms and comprises a
first transverse girder for supporting a first concrete tower
segment a second transverse girder for supporting a second
concrete tower segment parallel to the first transverse girder,
and two parallel radial girders both joined to the first and
second transverse girders; and
c. a central column with a column base that relies on the
mounting base, said central column comprising a telescopic
body consisting of a body and an extension, said central
column having a top end at which are disposed a plurality of
upper retractable arms each formed by a respective top
support bodyand top support extension;
3. assembling at least one pre-stressed concrete tower section by:
a. placing the plurality of concrete tower segments on the
slippable support;
b. tilting the concrete tower segments on the upper retractable
arms; and
c. vertically pre-stressing the assembled concrete tower
segments;
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4. for a first assembled pre-stressed concrete tower section:
a. attaching a lifting harness to the pre-stressed concrete tower
section;
b. hoisting the pre-stressed concrete tower section by means of
a crane connected to the lifting harness; and
c. mounting the pre-stressed concrete tower section on the
foundation;
5. for each subsequent superjacent assembled pre-stressed
concrete tower section, using the mounting assembly:
a. attaching a lifting harness to the pre-stressed concrete tower
section;
b. hoisting and mounting the pre-stressed concrete tower
section according to the same routine for mounting the first
assembled pre-stressed concrete tower section of the tower;
and
6. mounting a ring adapter, a flange for connecting a nacelle or wind
generator or heliostatic generator in the top part of the annular
pre-stressed concrete tower.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be better understood from the following detailed
description referred to the drawings which are not limitative of the present
invention, and where:
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Figure 1 shows a mounting assembly, for assembling at floor level
sections of a pre-stressed concrete tower from concrete tower segments.
Figure 2 depicts a mounting assembly arranged to assemble sections
of a tower, including flat and curved segments of concrete.
Figure 3 shows a assembled section of a tower which includes a lifting
harness.
Figure 4 shows an annular pre-stressed concrete tower showing the
horizontal and vertical pre-stressing tendons.
DETAILED DESCRIPTION OF THE INVENTION
According to the present invention, a section of the annular tapered tower
includes at least three concrete tower segments that once assembled are
hoisted and mounted in the tower. The sections are mounted in a well know
form, for example through the use of a fastening hoop (21) and a lifting
harness (22), with a crane. Then, mounting assembly (1) is used again for
assembling the following adjacent section of the tower.
Preferably, the tower includes three curved segments, all of the same
dimensions, separated by three flat trapezoidal segments with variable
dimensions, so the diameter of the sections depends on the sizes of the flat
trapezoidal segments. The section is then composed by six segments of
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concrete.
The tower includes pre-stressing tendons for the vertical and horizontal pre-
stressing of the tower. The horizontal pre-stressing has for object joining
adjacent segments to conform an annular section of the tower. The tower in
addition includes tendons of vertical pre-stressing, to keep joined concrete
sections and to the foundation, which render a structure having properties of
a monolithic one. The tower includes a foundation having means to anchor
the pre-stressing tendons, the vertical pre-stressing tendons runs along the
length of the tower, a plurality of tendons run along the whole length of the
tower whereas other vertical pre-stressing tendons only runs between
intermediate sections of the tower and the foundation.
The mounting assembly (1) and method to assemble at floor level sections
of an annular pre-stressed concrete tower for wind or heliostatic power
generators, is described:
Figure 1 depicts a mounting assembly (1) for use with sections of a pre-
stressed concrete tower at floor level. The mounting assembly (1) is placed
on a leveled platform (2) and includes a support (3) that includes a base (4)
consisting of three pair of double parallel arms (4a and 4b) that each extend
radially. Each of the double parallel arms has in its part more distant to the
center, a slippable support (5) for the first segments and the second
segments.
The slippable support (5is a rectangular frame that includes a first
transverse
girder (6) for support of the first segments, a second transverse girder (8)
for
support of the second segments, both transverse girders being parallel and
opposite, and being joined by two radial girders opposite (10,11) that
complete the frame.
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The first transverse girder (6) includes first receptacles (7a and 7b) to
receive
the base of a first segment of concrete. Likewise, the second transverse
girder (8) includes second receptacles (9a, 9b) to receive the base of a
second segment of concrete.
It is preferred that the first segments correspond to the trapezoidal flat
segments, while the second segments correspond to the circular segments.
The separation of the radial girders corresponds to the separation of the pair
of double parallel arms 4a, 4b so the frame formed by the girder 6, 8, 10 and
11 that form the slippable support (5) runs in the radial direction on the
double parallel arms to approach or to move away from the center of the
column. The slippable support (5) allows that the mounting assembly (1) of
the present invention could be used for assembling sections of tower of
different diameters. When the slippable support (5) moves away from the
center it is possible to assemble a section of bigger diameter. When the
slippable support (5) approaches the center of the mounting assembly (1) it
can be used to assemble tower sections of a smaller diameter.
The first transverse girder (6) has dimensions longer that the second
transverse girder (8), so that tangentially extends beyond distance between
the double parallel arms (4a, 4b), having besides a higher height providing
an upper level to the first trapezoidal flat segments regarding the second
segments. This height allows step (44), which it is suitable for preventing
the horizontal displacement of a tower sections regarding a subjacent or
superjacent one.
In the embodiment showed in the Figures, the position and dimensions of
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the first transverse girder 6 for first segments does not change regarding the
position and dimensions of the second transverse girder 8 for second
segments, due to the fact that according to the preferred embodiment the
circular segments always have the same width. On the other hand, the radial
displacement of the slippable support (5) allows the placement of the flat
trapezoidal concrete tower segments of different width.
In the case that the concrete tower sections are tapered, it is necessary to
provide slippable supports (5) for the adjustment of all concrete tower
segments, for example to form concrete sections of different diameters with
frustoconical annular sections.
The slippable support (5), on the double parallel arms (4a, 4b) are driven
through mechanical, pneumatic or hydraulic means (not illustrated) which
are well-known in the art. Likewise, the slippable supports (5) include means
to keep its position, these means include bolts that mate in perforations on
the double parallel arms (4a, 4b), or other mechanical, pneumatic or
hydraulic means well-known in the art.
The mounting assembly (1) of the present invention also includes a central
column (12), having a column base (13) that relies on the base (4) of the
mounting assembly (1). The column (12) has a telescopic body consisting of
a body (14a) and of an extension (14b) that extends in the longitudinal
direction. With the above mentioned arrangement the column can assume
diverse heights considered to be suitable for assembling a section of the
tower of a certain height.
At the top end of the column (12) are arranged a plurality of top support
arms,
which are depicted in the figures as three retractable arms (15a, 15b and
15c). The arms also are telescopic and there are each formed by a body
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(16a, 16b and 16c) that lodge a respective extension (17a, 17b and 17c) that
extend in radial direction to support the first concrete tower segments at a
certain height. Likewise, the retractable arms include means to retain a
certain position, such as bolts that mate in perforations in the body or the
extension of the arms, or other mechanical, pneumatic or hydraulic means
well-known in the art.
The arms 15a, 15b and 15c optionally include vertical supports 18a, 18b and
18c providing a surface where the flat face of a flat trapezoidal segment
relies. The vertical supports (18a, 18b and 18c) can include means to
provisionally join the arms to the concrete tower segments, for example
insertions including screws and nuts, in order to prevent the trapezoidal
concrete tower segments from collapsing out of the center of the mounting
assembly and causing damage to working personnel, the mounting
assembly or the concrete tower segments.
In addition, the support arms (15a, 15b, 15c) optionally include
reinforcements of arms (19) that consist of bars joined at each end of
respective arms to reinforce the above mentioned arms and to prevent the
retractable arms (15a, 15b, 15c) from being deformed by the force exerted
by the weight of the concrete tower segments.
The supports of the concrete tower segments, especially the receptacles 7a,
7b, and the retractable top arms as well as the possibility of extending or
contracting the central column and the slippable support (5) allow that the
concrete tower segments can be tilted to final position without risk of the
concrete tower segments falling or collapsing out of the mounting assembly.
The mounting assembly (1) also includes a fastening hoop (21) for lifting,
which is placed in the top end of the column (12). The hook of a derrick gets
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hooked up in the above mentioned hoop to ship and to land the mounting
assembly from a car of transport.
The mounting assembly (1) provides a structure that allows the assembling
of concrete tower segments. Under the preferred embodiment of the present
invention, a section of tower includes three first concrete tower segments
(flat trapezoidal) and three second concrete tower segments (curved). As it
will be apparent to a person skilled in the art, the segments of concrete can
be in several pieces and can have the same or different form.
Figure 2 depicts the mounting assembly (1) of the invention, which in a
preferred embodiment contains first flat trapezoidal concrete tower
segments (40) alternated with the second curved segments (30). In a
preferred embodiment, the curved concrete tower segments (30) incorporate
ducts (31) to introduce cables or rods of steel of high resistance as pre-
stressing tendons or strands for the vertical pre-stressing (51), and ducts
(32) to introduce horizontal pre-stress tendons (52a, 52b, 52c). In the
embodiment illustrated in Figure 2, the flat trapezoidal concrete tower
segments (40) only incorporate ducts (42) to introduce horizontal cables of
pre-stress (52a, 52b, 52c), but they do not include ducts for vertical pre-
stressing tendons so that only the curved segments include the ducts for
vertical pre-stressing. As it will be apparent to a person skilled in the art,
it
is possible to use flat trapezoidal concrete tower segments (40), which also
include vertical cables of pre-stress.
Inside the horizontal ducts (32 and 42) of the respective segments of
concrete flat and curved, are introduced pre-stressing tendons and, for the
pre-stressing action, the first flat concrete tower segments (40) and the
second curved concrete tower segments (30) remain fixed and firmly joined,
forming a structure with structural properties similar to those of a
monolithic
structure.
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In a preferred embodiment of the invention, the curved segments include
protrusions (33) in the inner face of the segment, which enable the
introduction and tensioning of the pre-stressing tendons. Under a preferred
embodiment of the invention, there are provided three horizontal pre-
stressing tendons (52a, 52b, 52c), every tendon joins three curved segments
and two flat segments in the following way:
- the first tendon 52a has for object join the first curved segment, the
first flat adjacent segment, the second curved segment, the second flat
segment and the third curved segment. But not the third flat segment.
- the second tendon 52b has for object join the second curved
segment, the second flat adjacent segment, the third curved segment, the
third flat segment and the first curved segment. But not the first flat
segment.
- the third tendon 52c has for object join the third curved segment, the
third flat adjacent segment, the first curved segment, the first flat segment
and the second curved segment. But not the second flat segment.
Each of the curved segments is joined by three pre-stressing tendons and
each one of the flat segments is crossed by two pre-stressing tendons. There
placed a plurality of projections (33) in the internal face of each curved
segments to a predetermined height. In Figure 2 the circular segment
includes six protrusions (33) with a separation of for example one meter.
The union obtained by the compression of the pre-stressing tendons
prevents that the segments could move along the lateral faces combined of
the curved and flat segments. So it is not need to use cemented unions to
join adjacent concrete tower segments. However, as it is apparent to a
person skilled in the art, shear locks and or cemented joints can be used.
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Preferably there is formed a step (44) that is useful for assembling two
sections of tower. Such a step (44) is provided by the difference of height in
the receptacles of the first segments (flats) (7a, 7b) and the second
segments (curved) (9a, 9b). As it is shown in Figure 1, the girder (6) for the
first segments is higher than the girder (8) for the second segments.
In a fist stage, preferably there are placed the flat trapezoidal segments
(40),
which are fixed firmly to the mounting assembly (1) on the first receptacles
(7a and 7b) and the vertical arm supports (18a, 18b and 18c), and in a
second stage there are placed the curved segments (30). The curved
segments are heavier that the flat segments, so two flat segments can
support the load due to the weight of an inclined curved concrete tower
segment. The above mentioned disposition is illustrative but not limitative,
since the flat trapezoidal segments and the curved segments can be installed
in consecutive form or in alternated form, to preference of the builder.
As soon as there is assembled a section of tower and the pre-stressing
tendons have been placed and tensioned, a lifting harness(22) is joint to the
assembled concrete section. The lifting harness(22) includes at least two
bars introduced in the ducts of vertical pre-stressing (31) and hold
themselves in such ducts by means of nuts incorporated into the thread ends
of the bars (23). The figure 3 shows a lifting harness assembled in an
assembled concrete section.
There are assembled so many sections of tower according to the design of
the tower. The first section is placed on the foundation and vertical means
of pre-stressing are provided to join the first section to the foundation.
Then,
the second section is assembled and mounted on the first section,
prestressing to the foundation is also conducted; the third and subsequent
sections are assembled, mounted and pre-stressed. As the sections are
mounted, vertical tendons of pre-stress are placed to join the sections with
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the underlying previous sections and the foundation. If the tower includes
cylindrical sections or a geometry different than the previously mounted
section, it is necessary to mount an adapter to join the sections of different
geometry. Finally, a flange is placed or adapted at the top of the tower and
there are placed pre-stressing tendons that run along the total body of the
tower, within all concrete sections. As previously mentioned, according to
the preferred embodiment of the invention, the vertical pre-stressing tendons
run only inside the concrete curved segments, but not inside the trapezoidal
flat segments. Figure 4 illustrates the vertical and horizontal pre-stressing
of
an annular concrete tower.
The present invention overcomes the drawbacks of the prior art, providing a
mounting assembly and method for assembling concrete sections of a tower
from concrete tower segments. The present invention provides a mounting
assembly and method for erecting a pre-stressed concrete tower that
includes:
(a) providing a mounting assembly (1) to support the concrete tower
segments to assemble sections of an annular pres-stressed concrete tower.
(b) providing a flat platform or level the floor, to place the mounting
assembly (1);
(c) to place the slippable supports (5) of the mounting assembly in a
suitable position corresponding to the dimensions of the base of the section
of tower, where the above mentioned supports (5) will support the base of
every segment of concrete by means of his respective receptacles (14a, 14b,
17a, 17b);
(d) to establish the position of the column extension to a suitable
height;
(e) to establish the position of the retractable arms, by means of
extending the extension of arm to allow the support of the first segments of
flat trapezoidal concrete tower segments, preferably on the ribs or
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reinforcement ribbing arranged to the inner side of every concrete tower
segment;
(f) to place the first flat trapezoidal concrete tower segments and
immediately the second curved concrete tower segments that form a section
of the tower, using a derrick of low or medium load capacity;
(g) to join the concrete tower segments with a plurality of horizontal
pre-stressing units. Under the present invention, every pre-stressing unit
including three pre-stressing tendons that hold joined three circular
segments and two flat segments.
(h) to connect a lifting harness assembled and pre-stressed concrete
section;
(i) to hoist the assembled section, by mean of a crane of high capacity
that incorporates a hook that engages the harness of elevation.
(j) to mount the above mentioned concrete section on the foundation,
and uncouple the lifting harness of the mounting assembly;
(i) to assemble the subsequent concrete sections constituting the
tower, with the mounting assembly. The slippable support adjusts the
diameter of the subsequent sections, which is minor that the section
previously assembled to yield a tapered tower;
(j) to mount the subsequent sections of the tower through the use of
the lifting harness, following the same routine for the first section of the
tower; and
(k) mounting an adapter, or flange for a wind power generator or
recipient heliostatic in the top part of pre-stressed concrete tower.
The method of the present invention also applies to towers of circular or
polygonal cross section. In such a case the first and second segments have
similar forms. Likewise, as it will be apparent to a person skilled in the
art, a
section of tower might be assembled from three, four, five, seven or eight
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segments of concrete.
From the above description of the invention a person skilled in the art
will find that the same can be modified in different ways. It is considered
that
such modifications do not apart from the spirit and the scope of the
invention,
and all these obvious modifications to a skilled in the art are included
within
the scope of the following claims.
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