Classifications

• • E—FIXED CONSTRUCTIONS
  • E04—BUILDING
  • E04H—BUILDINGS OR LIKE STRUCTURES FOR PARTICULAR PURPOSES; SWIMMING OR SPLASH BATHS OR POOLS; MASTS; FENCING; TENTS OR CANOPIES, IN GENERAL
  • E04H12/00—Towers; Masts or poles; Chimney stacks; Water-towers; Methods of erecting such structures
  • E04H12/02—Structures made of specified materials
  • E04H12/12—Structures made of specified materials of concrete or other stone-like material, with or without internal or external reinforcements, e.g. with metal coverings, with permanent form elements
• • E—FIXED CONSTRUCTIONS
  • E04—BUILDING
  • E04H—BUILDINGS OR LIKE STRUCTURES FOR PARTICULAR PURPOSES; SWIMMING OR SPLASH BATHS OR POOLS; MASTS; FENCING; TENTS OR CANOPIES, IN GENERAL
  • E04H12/00—Towers; Masts or poles; Chimney stacks; Water-towers; Methods of erecting such structures
  • E04H12/16—Prestressed structures
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
  • F03D—WIND MOTORS
  • F03D13/00—Assembly, mounting or commissioning of wind motors; Arrangements specially adapted for transporting wind motor components
  • F03D13/10—Assembly of wind motors; Arrangements for erecting wind motors
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
  • F03D—WIND MOTORS
  • F03D13/00—Assembly, mounting or commissioning of wind motors; Arrangements specially adapted for transporting wind motor components
  • F03D13/20—Arrangements for mounting or supporting wind motors; Masts or towers for wind motors
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
  • F05B2240/00—Components
  • F05B2240/90—Mounting on supporting structures or systems
  • F05B2240/91—Mounting on supporting structures or systems on a stationary structure
  • F05B2240/912—Mounting on supporting structures or systems on a stationary structure on a tower
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E10/00—Energy generation through renewable energy sources
  • Y02E10/70—Wind energy
  • Y02E10/72—Wind turbines with rotation axis in wind direction
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E10/00—Energy generation through renewable energy sources
  • Y02E10/70—Wind energy
  • Y02E10/728—Onshore wind turbines

Definitions

• the present invention relates to the technical field of superstructures.
• the subject of the present invention is a section of concrete intended to form a mast, notably for a windmill, a method for manufacturing the section of concrete, a mast of concrete comprising a set of sections comprising one or more of this section and a method to construct such a mast.
• the technical performance criteria can comprise the load that has to be supported by the mast, and hence the compression resistance of the used materials, but also the tensile resistance of these materials.
• the tensile resistance is important as the loadings on the mast can cause significant tensile stresses.
• the criteria linked to the logistics to be applied during the construction of the mast can, for their part, comprise the transportation of the various elements forming the mast from the production site where these elements are produced to the installation site, but also the conditions of assembling these elements on the installation site.
• concrete masts have an additional advantage compared to steel. Unlike steel welds, concrete joints present a good resistance to fatigue loading, which increases the durability of the mast and makes it a material of choice for the construction of masts of great height.
• a mast 1 notably for a windmill 2
• a mast 1 comprises a plurality of sections 10 of concrete stacked one on top of the other.
• French Patent application No. 1461713 describes such sections.
• a section 10 can be of a single piece or else, as illustrated in Figure 3, a section 10 can comprise a plurality of segments 3. Then, such a section is a modular section 10.
• the modular section 10 comprises four segments 3a, 3b, 3c, and 3d. These segments 3 can be assembled together by using means known to those skilled in the art, for example with vertical joints like those described in the document WO 2013/029743 A1.
• segments greatly facilitates the transportation of the elements of the mast to the site, since the segments can be stacked horizontally one on top of the other on a truck then assembled into sections at the installation site.
• a concrete section 10 presents an outer face E and an inner face I opposite the outer face E and arranged facing the internal volume V of section 10.
• section 10 is in the form of a hollow cylinder.
• Section 10 extends in a longitudinal direction X and comprises:
• first portion 11 intended to exert a bearing force on a lower adjacent part of the windmill 2, said first portion 11 comprising a first flange 11 ' extending substantially transversely from an internal face I of section 10 opposite the internal volume V of section 10, and
• the considered parts of the windmill 2 can be a lower adjacent section 10a of mast 1 , an upper adjacent section 10b of mast 1 , but also a nacelle, a transition piece of windmill 2 or the foundation structure of mast 1.
• the stress exerted on the concrete can vary over time because of the phenomenon of creep of concrete and of relaxation of the post-tensioning elements. In some cases, it is no longer possible, once the mast is erected, to control the post-tensioning elements which could inform about the effect of the phenomenon of creep of concrete and of relaxation of the post-tensioning elements.
• French patent application FR3029231 proposes in an embodiment a section as described above, wherein post-tensioning elements are arranged to apply a stress between the first portion 11 and the second portion 12 of a section 10.
• three sections 10a, 10b, and 10c are stacked one on the top of the other.
• the bars 13a facing the first section 10a are anchored to the foundation 14 and to the first portion 11 b of the second section 10b, which is the upper adjacent section for the first section 10a.
• the bars 13b facing the second section 10b are anchored to the second portion 12a of the first section 10a, which is the lower adjacent section for the second section 10b, and are anchored to the first portion 11 c of the upper section 10c, which is the upper adjacent section for the second section 10b.
• Post-tensioning operations are performed on each bar 13. It is therefore needed to mobilize devices for post-tensioning at different levels of the mast during the construction, i.e. for each section 10 except the upper one. Since iterative post- tensioning operations may be done to compensate for stress loss due to the deformation introduced by post-tensioning new bars, such operations can be burdensome.
• each section 10 must be designed to be able to accommodate a large number of anchoring points. Reinforcement portions may be needed, whereas the many holes in the flanges weaken the sections.
• patent application WO2010/098716 discloses prefabricated concrete wall elements for a tower construction stacked on each other and connected by means of bar elements.
• the bar elements may be connectable by threads and nuts.
• the bar elements are anchored at the top and bottom of the tower construction by means of anchorage.
• post-tensioning elements may be much longer than a section, because they are anchored to the foundation and to a higher section of the mast. The longer the post-tensioning elements, the more difficult it is to bring them up and to install them on site.
• patent application US2015/0052841 discloses post- tensioning strands which are anchored to the foundation of the tower and are capped off at different levels of the tower, which result in lengthy post-tensioning strands.
• the invention proposes a method for constructing a mast of concrete intended for a windmill which allows easier post-tensioning operations while simplifying the design of the sections and the construction process.
• a method for constructing a mast of concrete intended for a windmill said mast comprising at least an upper section of concrete and a lower section of concrete, each section comprising:
• the method comprising the step of, after the stacking of the sections, releasing the first post-tensioning element and the second post-tensioning element from the lower portion before anchoring the first post-tensioning element and coupling the second post- tensioning element, respectively.
• an upper end of the post-tensioning element pre-installed in the upper section is attached to said upper section by an attaching device while coupling a lower end of said post-tensioning element pre-installed in the upper section to the second post-tensioning element pre-installed in the lower section;
• each post-tensioning element is either anchored to the foundation or is part of an inter-section element intended to be anchored to the foundation, said inter- section post-tensioning element comprising at least one post-tensioning element pre- installed in one section coupled to another post-tensioning element pre-installed in another section.
• the concrete is an ultra-high performance concrete or an ultra-high performance concrete reinforced with fibres and /or with ordinary reinforcement; - for each section of concrete:
• the first portion comprises a first flange extending substantially transversely from an internal face of the section opposite the internal volume of the section,
• the second portion comprises a second flange extending substantially transversely from the internal face of the section opposite the internal volume of the section,
• the first post-tensioning element pre-installed in the lower section is anchored to the first flange of the first portion of the upper section.
• the invention in another aspect, relates to a section of concrete adapted to be used in the method for constructing a mast of concrete, said section having an internal volume and comprising;
• section comprises:
• first post-tensioning element attached to the section in the internal volume of said section and configured to be anchored in the first portion of an upper section of the mast
• first post-tensioning element and the second post-tensioning element are pre-installed to the lower section by an attaching device adapted to release the first post-tensioning element and the second post-tensioning element from the lower portion before anchoring the first post-tensioning element and coupling the second post- tensioning element, respectively.
• the invention in another aspect, relates to a mast of concrete intended for a windmill, said mast comprising at least an upper section of concrete and a lower section, said upper section being stacked on the top of the lower section, the first portion of the upper section extending the second portion of the lower section, each section comprising - a first portion exerting a bearing force on a lower adjacent part of the windmill, and
• a first post-tensioning element pre-installed in the lower section by an attaching device is anchored to the first portion of the upper section after release from the attaching device
• a second post-tensioning element pre-installed in the lower section by an attaching device is coupled to a post-tensioning element pre-installed in the upper section after release from the attaching device.
• post-tensioning elements coupled together form an inter-section element
• each post-tensioning element is either anchored to the foundation or is part of an inter-section post-tensioning element anchored to the foundation, said intersection post-tensioning element comprising at least one post-tensioning element facing one section coupled to another post-tensioning element facing another section.
• FIGS. 7a-7c show steps of a method for constructing a mast of concrete intended for a windmill according to a possible embodiment of the invention.
• a concrete section 10 presents an outer face E and an inner face I opposite the outer face E and arranged facing the internal volume V of section 10.
• section 10 is in the form of a hollow cylinder.
• Section 10 extends in a longitudinal direction X and comprises:
• first portion 11 intended to exert a bearing force on a lower adjacent part of the windmill 2, said first portion 11 comprising a first flange 11 ' extending substantially transversely from an internal face I of the section 10 opposite the internal volume V of the section 1 ,
• a second portion 12 intended to form a bearing support for another upper adjacent part of the windmill 2, said second portion 12 comprising a second flange 12' extending substantially transversely from the internal face I of the section 10 opposite the internal volume V of section 10.
• the considered parts of the windmill 2 can be a lower adjacent section 10a of the mast 1 , an upper adjacent section 10b of the mast 1 , but also a nacelle, a transition piece of the windmill 2 or the foundation structure of the mast 1.
• the section is made of ultra-high performance concrete or of ultra-high performance concrete reinforced by fibres, for example with compressive strength of at least 120 MPa, preferentially of at least 150 MPa at 28 days and/or with tensile strength at 28 days of at least 5 MPa, preferentially of at least 7 MPa, even more preferentially 9 MPa and/or with a Young's modulus of at least 45 GPa, preferentially of at least 50 GPa and more preferentially of at least 55 GPa.
• This concrete can, for example, be of the type of that marketed by the company Lafarge under the trademark Ductal®.
• the use of this type of concrete makes it possible to produce a lighter mast 1 than with a traditional concrete while retaining a reduced section diameter that notably allows for the transportation of sections presenting a length from 10 m, preferentially 20 m, even more preferentially 25 m as one entire section from the production site to the installation site.
• a section 10 made of one entire concrete section which can be made of one-piece concrete section 10 if it is not formed from a plurality of segments 3, can have an outer diameter that can range up to the local transportability limits on roads, for example up to 4.2 m or 4.4 m. .
• the section 10 extends in a longitudinal direction and preferably comprises:
• first flange 11 ' extending substantially transversely from an inner face I of section 10 in the internal volume V of section 10, said first flange intended to exert a bearing force on a lower adjacent part of the windmill 2 in the longitudinal direction;
• the sections 10 are built on a production site and are brought to the construction site where the mast 1 is to be erected. As shown by figure 7a, after a first section 10a is erected on a foundation, a second section 10b is stacked above the first section 10a, which becomes the lower section.
• post-tensioning elements 20, 21 , and 22 are pre-installed post-tensioning elements 20, 21 , and 22.
• the post-tensioning elements 20, 21 , and 22 are typically cables, and in the following description, cables are used in a non-limiting way as examples of post-tensioning elements.
• At least two types of post-tensioning cables 20, 21 , and 22 are pre-installed in a section 10:
• first section 10a are pre-installed: - first post-tensioning cables 20a that are intended to be anchored to the first portion of the second section 10b, which is the upper adjacent section with respect to the first section 10a, and
• Post-tensioning cables 20, 21 , and 22 of both types are distributed over the circumference of a section 10, and their number depends of the post-tensioning to be performed.
• Post-tensioning cables 20a, 21 a, and 22a pre-installed in the first section 10a of the both types are intended to be anchored by their lower ends to the foundation 1 on which the first section 10 a is erected.
• the upper ends of the first post-tensioning cables 20 are then anchored to the first section 1 1 b of the second section 10b at anchorages 23. More precisely, they are anchored to the first flange 1 1 'b of the second section 10b by means of an anchoring device 15a. The lower ends of the first post-tensioning cables 20 are then anchored to the foundation 14 on which is erected the first section 10a by anchorages 24a.
• Post-tensioning cables 20b and 21 b pre-installed in the second section 10b of the both types are intended to be coupled by their lower ends to post-tensioning cables 21 and 22 pre-installed in the lower sections, i.e. pre-installed in the first section 10a.
• the first post-tensioning element 20a pre-installed in the first section 10a are anchored to the first portion of the second section 10b, more precisely to the first flange 1 1 ' by an anchorage 23a.
• the second post-tensioning elements 21 a, 22a pre- installed in the first section 10a are coupled to the post-tensioning element 20b, 21 b pre-installed in the second section 10b, by couplers 25a, 26a.
• the coupled post-tensioning cables 21 a, 22a, 20b, and 21 b passes in the internal volume V of the concrete section 10. They do not need to enter hole in flanges 1 1 and 12, and the couplers 25a, 26a between cables can stay outside of the concrete section 10. This reduces the occupation of holes on the flanges. As the number of holes on the flanges 11 and 12 is limited, the stresses taken by each hole can be reduced for a total given amount of stress to be applied, which is beneficial of a lower risk of cracking.
• the post-tensioning cables 20, 21 , and 22 pre-installed in a section 10 are pre-installed to said section 10 by releasable attaching devices, preferably arranged on the inner face I of section 10.
• the post-tensioning cables 20, 21 , and 22 are thus temporarily fixed to the section 10.
• Tower internals such as a platform of a ladder, fixed to a section 10, may also serve as attaching devices, by attaching the post-tensioning cables 20, 21 , and 22 to said tower internals.
• the post-tensioning cables 20, 21 , 22 are pre-installed to their respective sections 10 so that their lower ends are free. This allows anchoring or coupling said lower ends of the post-tensioning cables 20, 21 , 22. It should be noted however that the lower ends of post-tensioning cables 20, 21 , 22 pre-installed in a section 10 may be attached to said section 10, especially during transportation from the production site, before being released for the purpose of anchoring or coupling them with post-tensioning cables 20, 21 pre-installed in the lower adjacent section 10.
• the post-tensioning cables 20, 21 , 22 are depicted attached by their upper ends to the inner face I of each section 10. Indeed, the upper ends of the post- tensioning cables 20, 21 , 22 are kept attached to the section 10 when the lower ends of post-tensioning cables 20, 21 , 22 are anchored or coupled. This allows keeping the post- tensioning cables 20, 21 , 22 in a favourable handling configuration. The upper ends of the post-tensioning cables 20, 21 , 22 are released when they have to be anchored to the upper adjacent section 10 or coupled with post-tensioning cables 20, 21 , 22 pre- installed in the upper adjacent section 10.
• the post-tensioning cables 21 b and 22b pre-installed in the second section 10b are still attached to the second section 10b by their upper ends and are therefore ready to be used with an upper adjacent section.
• the anchors can be pre-installed on each section 10 at the anchorage points, so that the post-tensioning cables 20, 21 , and 22 can be anchored without having to bring up the anchors.
• a first post-tensioning operation can be performed on the first post-tensioning cables 20a.
• a third section 10c is then stacked above the second section 10b.
• the upper ends of the first post-tensioning cables 20b pre-installed in the second section 10b are then released from their attaching device and anchored to the first portion of the third section 10c, and more precisely to the first flange of said third section 10c by anchorages 23b.
• Each inter-section post-tensioning cable formed by a second post-tensioning cable 21 a pre-installed in the first section 10a and coupled to a first post-tensioning cable 20b pre-installed in the second section 10b is anchored to the foundation 14 on which is erected the first section 10a by anchorages 24b.
• the lower ends of the second post-tensioning cables 21 a pre- installed in the first section 10a and coupled to the first post-tensioning cables 20b pre- installed in the second section 10b are anchored to the foundation 14 on which is erected the first section 10a by anchorages 24b.
• the mast 1 comprises four sections 10.
• a mast 1 may comprise more or less than four stacked concrete sections 10.
• the erection of the others sections 10 is similar as for the second section 10b, except for the penultimate section and the last uppermost section, which may be different.
• a fourth section 10d is mentioned in order to allow the third section 10c to be properly post-tensioned, and therefore is described as a section without pre-installed post-tensioning elements anchored above it.
• every concrete section 10 must be post-tensioned with post-tensioning elements anchored above said concrete section.
• Post-tensioning elements pre-installed in the uppermost section of the concrete mast 1 should therefore normally be anchored to a transition piece between the concrete mast 1 and the nacelle of the windmill.
• the fourth section 10d may be construed as a transition steel piece and the third section 10c as the uppermost section.
• the third section 10c is the penultimate section before the top of the mast 1 , i.e. it has only one upper section.
• Only first post-tensioning cables 20c are pre-installed in this third section 10c, which are intended to be anchored to the first portion of the upper adjacent section.
• the lower ends of the first post-tensioning cables 20c are coupled to the second post-tensioning cables 21 b pre-installed in the second section 10b by means of a coupler 26b.
• the fourth section 10d is then stacked above the third section 10c.
• the uppermost section 10d does not have pre-installed first post-tensioning cables 20 intended to be anchored to the upper adjacent section with respect said section 10, or pre-installed second post-tensioning cables 21 and 22 intended to be coupled to other cables pre-installed in upper sections.
• First post-tensioning cables 20c pre-installed in the third section 10c are anchored to the first portion of the fourth section 10d.
• the upper ends of the first post- tensioning cables 20c pre-installed in the third section 10c are then released from their attaching devices and anchored to the first portion of the fourth section 10d, and more precisely to the first flange of said fourth section 10d by anchorages 23c.
• Each inter-section cable formed by a second post-tensioning cable 22a pre- installed in the first section 10a and coupled with a second post-tensioning cable 21 b pre-installed in the second section 10b which is coupled with a first post-tensioning cable 20c pre-installed in the third section 10c is anchored to the foundation 14 on which is erected the first section 10a by an anchorage 24c.
• the lower ends of the second post-tensioning cables 22a pre- installed in the first section 10a and coupled with the second post-tensioning cables 21 b pre-installed in the second section 10b which are coupled with the first post-tensioning cables 20c pre-installed in the third section 10c are anchored to the foundation 14 on which is erected the first section 10a by anchorages 24c.
• Each post-tensioning cable 20, 21 , and 22 is either anchored to the foundation 14 or is part of an inter-section post-tensioning cable anchored to the foundation 14. In fact, only the first post-tensioning cables 20a pre-installed in the first section 10a is directly anchored to the foundation 14. The other post-tensioning cables 20, 21 , and 22 are parts of inter-section post-tensioning cables.
• the post- tensioning devices are arranged on the top surface of the flanges 11 ', 12' during post- tensioning of the post-tensioning elements.
• the flanges 11 ', 12' therefore need to have a minimum free space left on the top surface of the flanges 11 ', 12' extending from the inner face I of a section 10 in order to accommodate post-tensioning devices. It is usual to keep at least 6 cm between the inner face I and the anchorage points of the post- tensioning elements.
• the design of the flanges 1 1 ', 12' can be optimised.
• anchorages 23 can be close to the inner face I of the section 10, closer than 6 cm.
• the flanges 11 ', 12' can thus be made shorter, i.e. less protruding in the internal volume V.
• the eccentricity (with respect to the walls of the section 10) of the applied stress is reduced. The moment of force applying to the flanges 1 1 ', 12' is therefore reduced.
• the anchorage points 24 for the cables are positioned at the foundation level of the mast 1 and on the top surface of the first flanges 11 of the concrete sections 10. This enables a stiffer design, which is very beneficial for reducing the stress concentration within the section 10, especially near the flanges 11 ' and 12'.
• the second flange 12' may have stiffeners arranged in the internal volume V along the inner face I of the section 10. It shall be noted that fewer couplers 25, 26 are required for achieving a same target post-tensioning stress as in the prior art. The reduction is also beneficial for a more optimized site construction procedure.

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• Engineering & Computer Science (AREA)
• Architecture (AREA)
• Chemical & Material Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Mechanical Engineering (AREA)
• Combustion & Propulsion (AREA)
• Sustainable Energy (AREA)
• General Engineering & Computer Science (AREA)
• Sustainable Development (AREA)
• Civil Engineering (AREA)
• Structural Engineering (AREA)
• Materials Engineering (AREA)
• Wood Science & Technology (AREA)
• Wind Motors (AREA)

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Citations (5)

• 2015
  • 2015-12-17 FR FR1562706A patent/FR3045696A1/fr not_active Ceased
• 2016
  • 2016-12-15 WO PCT/EP2016/081148 patent/WO2017102925A1/en active Application Filing

Patent Citations (5)

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