The invention relates to a floating foundation supporting framework for offshore structures for positioning functional units in a floating position. Such floating foundation supporting frameworks may hold and support off-shore wind power plants, light towers, transmitter and/or receiver plants, radar plants, bridges, jetties, landing strips or the like, near a coast-line or also at a greater distance from a coast-line.
Floating foundations have been known, for example, for light towers or also for wind power plants. Regarding this, reference is made to DE 10 2005 036 679.1, this document relating to anchorages of floating foundations on the ocean floor.
Large plants such as medium-performance and high-performance wind power plants frequently have considerable weight that needs to be compensated by appropriate floating bodies. These must generate buoyancy forces that must by far exceed the weight of the structure to be supported as well as that of the floating foundation in order to thus hold still the affected structure, irrespective of wave action and wind influence. To accomplish this, the necessary buoyancy forces may add up to several thousand tons.
Frequently, floating foundations must necessarily span a relatively large area. The buoyancy forces applied to individual points by the buoyancy elements must be safely absorbed and tolerated by the building structure
In addition to the requirements regarding the stability of the foundation under load, there are requirements regarding the manufacturing options and costs affecting an appropriate building construction in practical applications. For example, the logistics as well as the construction efforts, material expenses and, finally also maintenance expenses, should be kept within limits. Until now, floating foundation structures have displayed deficits regarding at least one of the mentioned aspects.
Considering this, it is the object of the invention to provide a floating foundation supporting framework that has been improved with regard to at least one of the mentioned aspects when compared with known building structures.
This object is achieved with the floating foundation supporting framework in accordance with claim 1:
The supporting framework comprises buoyancy elements, at least one of said buoyancy elements consisting at least partially of concrete, and comprises connecting elements, said connecting elements consisting of steel and forming a supporting framework. By making the buoyancy elements at least partially of concrete, it is possible to considerably lower the manufacturing costs. This applies, in particular, to geometrically complex shapes such as, for example, the junction regions that must be designed hollow in order to make walking on the structure possible. This also applies to buoyancy elements that are located at the outer ends of a supporting framework that is star-shaped, for example, in order to introduce buoyancy forces into the supporting framework at that location. In particular, the lower parts or bottoms of buoyancy elements may be made of concrete. Due to the rigidity of reinforced concrete elements, such elements may have a flat bottom or a only slightly arched bottom, for example.
The use of concrete for the manufacture of a floating foundation supporting framework minimizes the use of steel and thus reduces corrosion problems and prime costs.
Preferably, the floating foundation supporting framework comprises several cantilevers that extend horizontally when in use, as well as junction points from which extend inclined and horizontal pipe segments. The supporting framework consists of a load-transferring spatial trussed structure, preferably configured as prefabricated steel structures and, e.g., as hollow elements generating buoyancy forces in the junction regions. These structures preferably have the form of reinforced concrete components and are made of or consist of, for example, water-impermeable concrete. The junction regions are preferably designed so as to be hollow and patent in order to ensure that it is possible to walk on the cantilever regions. Preferably, the supporting framework is designed in such a manner that the buoyancy forces and the load-transfer in the junction points of the pipe segments are uncoupled in the entire cantilever region and in the connecting region of the buoyancy elements, said buoyancy elements preferably being arranged on the extreme outside, and are associated with the specific supporting framework elements, respectively. As a result of this, clear load conditions are established and undesirable double loads or overloads are prevented.
The supporting framework in accordance with the invention is erected in mixed construction with the use of steel and concrete, preferably water-impermeable concrete. Said framework is designed in part as a shell supporting framework and in part as a bar-type supporting framework. For example, the shell supporting framework comprises pipe segments consisting of steel or also of reinforced steel components that are designed, for example, as junction point. The bar-type supporting framework comprises trussed structure sections, for example, consisting of steel piping or other steel profiles. The bar-type supporting framework is connected to the shell supporting framework, so that the shell supporting framework and the bar-type supporting framework, together, form the foundation supporting framework.
The overall supporting behavior is defined, in the junction points of the supporting framework and in the cantilevers, by the trussed construction. The buoyancy forces due to locally applied loads occur at the junctions and on the cantilevers due to reinforced concrete components or, in the cantilever regions, also due to pipe segments.
Preferably, the outlying buoyancy elements are upright cylinders whose lower cup is configured as a circular cylindrical shell. A steel shell structure is set on said circular cylindrical shell, said steel shell structure preferably being manufactured as a prefabricated cup-shaped circular cylindrical shell that is open in downward direction.
At the junction points, the reinforced steel components are connected to the steel structures. To do so, preferably, water-impermeable, corrosion-resistant assembly techniques are employed. Steel pipes or steel socket ends can be fitted to hollow concrete elements by means of elastomer elements or the like.
The design of the supporting framework in mixed construction comprising shell supporting frameworks and bar-type supporting frameworks allow a high degree of variability regarding the requirements for the inert mass distribution in the total system. In addition, it is possible to adapt the system requirements to wind power plants designed for six megawatts and above. In addition, the modules of the system such as, for example, the components of the trussed structure and the components of the shell supporting structure may be prefabricated. The plant may be erected in the dry dock or also on site. For example, assembled system modules may undergo final assembly in the dry dock, whereupon the foundation supporting framework is towed to the installation site. As a result of the prefabrication of the modules, it is only necessary to perform the final assembly in the dry dock. This minimizes the required dwell time in the dry dock and thus permits the efficient production of a larger number of floating supporting frameworks.
Preferably, the load introduction of the lower guy occurs in trussed construction. Preferably, this is at the ends of the cantilevers without any load being applied to the buoyancy elements. Consequently, the supporting framework absorbs the forces of the guy as well as the forces of the buoyancy elements. However, it is also possible to impart the pulling forces of the guy as well as the force of the weight of the structure, respectively, as pressure (completely) into the concrete coups (see
With the foundation supporting framework presented herein, it is possible to erect—in a cost-neutral manner—building structures in depths of up to one thousand meters, irrespective of the depth of the water.
The system in accordance with the invention enables an optimal adaptation of the system mass distribution over variably designed ballast elements, preferably by arranging additional masses in the form of prefabricated components of reinforced concrete. These components may be arranged, as needed, at various locations of the entire trussed structure of the cantilevers. Such masses may also be disposed to increase mass inertia, avoid vibrations, attenuate vibrations, reduce vibrations and the like.
Optimally, the total buoyancy force may be adapted to various requirements by additionally providing variably designed buoyancy components, preferably in the form of spherical hollow bodies, in the entire region of the trussed structure of the cantilevers.
Additional details of advantageous embodiments of the invention are the subject matter of the drawings, the description or the claims. The description is restricted to essential aspects of the invention and other situations. The drawings disclose additional details and are to be used for supplementary reference. They show in
The foundation supporting framework 4 is a mixed steel and concrete structure. Said structure comprises several cantilevers 11, 12, 13 that extend radially outward from a central spatial trussed structure 14, for example in the form of a tetrahedron. Considering several aspects, the foundation supporting framework 14 is designed in mixed construction. Said framework is designed, in part, as a shell supporting framework and in part as a bar-type supporting framework. In addition, said framework includes steel elements as well as concrete elements. The spatial trussed structure 14 comprises pipe segments 15, 16, 18, 19, 20 that form the sides of a tetrahedron and are connected to each other at strut attachment fittings 21, 22, 23, 24. The relatively large diameter of the pipe segments 15 through 20 makes it possible that each pipe may be viewed as a shell supporting framework. The strut attachment fittings 21 through 24 are hollow and lead to additional pipe segments 25, 26 that preferably extend approximately horizontally and radially away from the center of the foundation supporting framework 4 in outward direction toward the buoyancy elements 28, 29, 30. Preferably, the strut attachment fittings 21 through 24 consist of reinforced steel, however, they may also consist of steel piping. In particular, this applies to the strut attachment fitting 21. By means of salt-water-resistant, corrosion-resistant and tight junctions said fittings are connected to the respectively adjacent pipe segments 15 through 20 and 25, 26. The strut attachment fittings 21 through 24 are largely load-free. However, their presence contributes to the total buoyancy of the building structure. They are surrounded by a cage-like bar-type framework. This is obvious from
Preferably, each of the cantilevers 11, 12, 13 is configured as a spatial bar-type supporting framework. This can be seen in
The buoyancy element 29 is hollow and may be walkable. The pipe segment 26 may be connected to the concrete element 38 by means of a connecting piece 41. Walls, cross-walls or the like may be provided on the connecting piece 41 and/or in or on the pipe segment 26, in which case said walls can be locked if necessary.
The buoyancy element 29 is anchored to the cantilever 12 by means of connecting means. Preferably, these means are arranged on the upper region of part 38 in order to transmit the upthrust buoyancy force acting on part 38 as pressure force to the cantilever 12. Attachment means may be steps provided on the concrete element, anchors set therein, steel plates and the like, these being connected to the cantilever 12. Preferably the steps, as shown by
In addition, the cantilever 12 has connecting arrangements 42 for the cable 10. The connecting arrangement 42 imparts the pulling force of the cable 10 into the cantilever 12. To do so, individual struts 43, 44 are provided, said struts extending downward from the cantilever 12 and connecting said cantilever with the cable 10.
It is also possible to provide a leveling arrangement that is, e.g., hydraulically actuated, said arrangement holding a vertically adjustable bar 45, as indicated in
Alternatively, the leveling arrangement may also be arranged at another location such as, for example, below part 38, as is shown by
As indicated only by dashed lines in
A cross-section of the machine room is shown separately in
The dimensions of the floating body comprising several buoyancy elements is not a function of the supporting framework components, the design of said supporting framework components being a function of the load distribution pattern. In order to achieve a suitable distribution of mass, it is possible to adapt the system's mass distribution over variably configurable ballast elements, preferably by providing additional mass in the form of prefabricated reinforced concrete parts at suitable locations of the trussed framework structure. The cantilever comprises steel profiles and is attached at the junction points of the spatial trussed frameworks that connect the horizontal and inclined pipe segments with each other. The spatial trussed frameworks may form cages that circumscribe the junction points. The attachment of the spatial trussed frameworks to the pipe segments is accomplished via a load-distribution (round or rectangular) ring-shaped hollow box girder. In order to achieve the statically required total buoyancy force, it is possible to additionally provide buoyancy components displaying variable design, preferably having the shape of spherical hollow bodies, in the entire region of the trussed structures of the cantilevers.
Preferably, the completely prefabricated foundation supporting structure with the wind power plant set on top in horizontal floating position is taken to its location of use and then connected on-site with the anchoring elements. The winches 54 are used to lower the floating supporting structure, said winches being blocked at a desired immersion depth, e.g., with the use of brakes. A continuous fine adjustment of the floating position may be carried out with the hydraulic cylinders. With the use of the invention, it is possible to achieve a load transfer through diagonal supports preferably having the form of pipe segments of steel and spatial trussed structures of steel, while buoyancy is preferably ensured by buoyancy elements that are located far outside.
Hereinafter is a list of individual features and aspects that may be of importance in conjunction with the invention. The floating foundation supporting framework is intended, in particular, for offshore constructions for positioning functional units in floating position on or in water, in particular on or in the ocean, and is suitable for depths up to 1000 (one thousand) meters. Said floating foundation framework comprises several buoyancy elements that are connected to each other by supporting structures, preferably prefabricated steel and concrete structures, and optionally comprises ballast elements, and acts as a foundation or as a platform for a functional unit. By means of pulling elements, the foundation supporting framework is connected to anchoring elements set on the ocean floor in the manner of concrete construction. The horizontal cantilevers support the buoyancy elements and—like the connecting junctions of inclined or horizontal pipe segments—consist of load-transferring steel structures, whereby buoyancy-generating hollow elements in the form of prefabricated reinforced concrete components of water-impermeable concrete are arranged in the junction regions, said hollow elements ensuring the walkability of the cantilever regions.
The “buoyancy” and “load-transfer” functions are uncoupled from each other at the connecting junctions of the pipe segments in the entire cantilever region and in the connecting region of the buoyancy elements that are located far outside, and are respectively associated with specific supporting foundation elements. Construction includes mixed construction using steel and high-performance concrete. Preferably, the structure is a combination of shell supporting frameworks of materials such as high-performance concrete and/or steel, prefabricated reinforced concrete parts and/or pipe segments and bar-type supporting frameworks of steel.
The total supporting behavior is characterized by the trussed framework construction in the junctions and in the cantilever region, and the local load introduction of the buoyancy forces in the junctions and in the cantilever region. The local load introduction of the buoyancy forces occurs in the junctions due to the prefabricated reinforced concrete parts. In the cantilever region, the load introduction may also occur by pipe segments. The buoyancy elements are manufactured, in mixed construction, as prefabricated reinforced concrete parts—preferably as a shell having the form of a circular cylinder with a lower bottom plate and steel shell construction—preferably as a prefabricated shell having the form of a circular cylinder. The interfaces between the concrete construction and the steel construction are formed in the connecting junctions and in the connecting regions of the buoyancy elements, said interfaces being designed as a water-impermeable, corrosion-resistant transition construction in steel construction manner. A high degree of variability is achieved regarding the inert mass distribution requirements for the total system. It is possible to adapt the system requirements of wind energy plants up to 6 megawatts. Due to the use of system modules, a high level of prefabrication is achieved. Modular assembly systems in semi-fabricated manufacturing condition can be delivered to final assembly. The load introduction of the cable forces takes place from the lower transfer into the trussed framework structure at the end of the cantilever, without stressing the buoyancy element. The manufacture of the system is cost-neutral, independent of the water-depth for depths up to 1000 (one thousand) meters. The system mass distribution can be optimally adapted by ballast elements of variable configuration—preferably by providing additional mass in the form of prefabricated reinforced concrete components—in the entire region of the trussed framework structure of the cantilevers. Optionally, it is possible to adapt the total buoyancy force by additionally providing buoyancy elements of variable configuration, preferably in the form of spherical hollow bodies, at any point of the trussed framework structure of the cantilevers. The planning objective can be illustrated for a 3-megawatt wind power plant. The development of cantilever modifications for plants of up to approximately 5 to 6 megawatts is possible. The anchorage of the foundation system can be implemented by means of anchoring elements to be provided on the ocean floor, preferably by heavy-weight foundations in concrete construction, said heavy-weight foundations being manufactured on site.
The floating foundation supporting framework according to the invention for offshore structures comprises a plurality of buoyancy elements which are arranged on the outside of a bar-type supporting framework which, in turn, is connected to ballast elements via cables 8, 9, 10. This design results in a simple construction and low construction costs.
1 wind power plant
2 mast
3 floating foundation
4 foundation supporting framework
5, 6, 7 ballast elements
8, 9, 10, 10a, 10b cables
11, 12, 13 cantilevers
14 spatial trussed structure
15, 16, 17, 18, 19, 20 pipe segments
17
a box profile
17
b socket end
17
c, d flanges
21, 22, 23, 24 strut attachment fittings
24
a permanent formwork
25, 26 pipe segments
28, 29, 30 buoyancy elements
31 cage
32, 33, 34 box girder
35 bar-type framework
35
a,
35
b corbels
35
c support
36 upper side
37 bottom
38 lower part of buoyancy element
39 upper part of buoyancy element
40 seal
41 connecting piece
42 connecting arrangement
43, 44 struts
45 bar
46 seal
47 chamber
48 hydraulic adjustment arrangement
49
a, b lateral supports
50-53 box profile supports
54 winch
55, 56 cable sheaves
57 shaft
58, 59 bearing blocks
60, 61 hydraulic cylinder
62, 63 seals
64 support
65, 66 dividing walls
67 torque bracket
68 ballast element
69 buoyancy element
Number | Date | Country | Kind |
---|---|---|---|
10 2008 003 647.1 | Jan 2008 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/EP2009/050186 | 1/9/2009 | WO | 00 | 3/9/2011 |