WO2016187720A1

WO2016187720A1 - Modular assembly for on-site fabrication of a structure

Info

Publication number: WO2016187720A1
Application number: PCT/CA2016/050599
Authority: WO
Inventors: Jeff Bradfield; Tony De La Concha
Original assignee: Anchor Concrete Products Ltd.
Priority date: 2015-05-26
Filing date: 2016-05-26
Publication date: 2016-12-01

Abstract

There is provided a hollow, continuous assembly, which is assembled from individual modules. Each module is a hollow structure defined by spaced apart upper and lower plates and opposing first and second end walls, at least one of said modules having a port for introducing a flowable material into the interior of said modules. The modules have an opening that allow the modules to be in fluid communication with each other whereby an essentially continuous interior space is defined within the assembly for filing with the flowable material. The flowable material may be concrete to form a solid, monolithic base for a wind generator or other large structure, or alternatively a liquid such as water. There is a also provided a method for fabricating a structure by assembling multiple such modules and filing the interior space with a flowable material.

Description

MODULAR ASSEMBLY FOR ON-SITE FABRICATION OF A STRUCTURE CROSS REFERENCE

[0001] This application claims Paris Convention priority to United States patent application number 62/166,435 filed on May 26, 2015. The contents of said application are incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The invention relates in particular to an assembly that can serve as a base for a wind turbine tower or other large structure, or alternatively as a tank for retaining water or other liquid. In particular, the invention relates to a modular concrete structure that may be assembled at a job site into a hollow structure that may be filled with concrete to provide a base for supporting a large structure such as a tower for a wind turbine or other structure. In other aspects, the hollow structure may be used as a retention tank for water or other fluid.

BACKGROUND

[0003] Large outdoor structures such as free-standing towers (and in some cases supported towers) often require a large base to provide support. An example of such a structure is a wind turbine.

[0004] Conventional wind turbines are supported on a large tower which supports a rotor which includes blades for converting wind energy to low speed rotational energy, a gearbox and a generator. Typically, the tower maybe 60-80 meters in height or more, with blades of 30-40 meters in length or more. The turbine can generate considerable forces on the tower which are then transferred to the base. In order to support the relatively large structure of a conventional wind turbine and resist the forces imposed on the structure, the tower is typically supported on a large and massive base. The base must provide a solid platform for the tower to transmit the weight and forces of the wind generator to the underlying bedrock or other ground surface on which the base rests. For example, the base may comprise a platform having more than 1,000 tonnes of concrete and steel rebar which can be 10-18 meters across and 2 or more meters in height. Other large structures can also require a similar large and massive base. In many cases, such structures are erected in remote locations where it can be difficult to transport a large base. Fabrication of such structures entirely on- site can be difficult, time-consuming and costly.

[0005] In other aspects, large water storage tanks are sometimes provided in locations that are remote from a concrete fabrication plant. Water storage tanks can be used to impound drainage water, sewage or run-off. As well, large tanks can be used for storing agricultural (irrigation) water or chemicals as well as other uses. In many cases, installation of storage structures of this type gives rise to similar difficulties in transport and erection as bases for large towers, in that they are too large to be easily transported and handled with conventional equipment. As is the case with large bases for towers, it can be difficult to fabricate such structures entirely on-site.

[0006] In most-cases, off-site fabrication of a large one piece base or tank structure is impractical, since a structure of this size and mass cannot be easily transported to a remote wind farm site or other remote installation location. Various solutions have been proposed for structures which can be partially fabricated off-site, with assembly or other finishing performed on-site. For example, U.S. 8,359,798 discloses a base for a wind turbine having a central platform surrounded by multiple segments. The segments are fabricated off-site and individually shipped to the job site, where they are assembled into the base structure. Similar structures are described in U.S. patent numbers 8,607,517 and 8,695,297. In other solutions, a hollow structure may be provided, which is then filled with concrete or other filling material on-site to increase the mass of the base structure.

SUMMARY

[0007] It is an object of the present invention to provide a modular, hollow assembly that can be filled with a material such as concrete to serve as a base for a wind turbine or other large tower-based structure and, in other embodiments, as a tank for retaining a fluid such as water. The assembly is formed from multiple modules which may be individually shipped to a job site where they are assembled into a hollow structure. [0008] According to one aspect, the invention relates to an assembly comprising a plurality of hollow modules configured for assembly into a hollow structure composed of contiguous modules. The hollow structure may then be filled with concrete or other material to form a monolithic, solid base. The modules each comprise a hollow structure defined by spaced apart upper and lower plates and opposing first and second end plates. The modules are configured for assembly into a structure having a continuous uninterrupted hollow interior space that extends through all or at least multiple ones of the modules. At least one of the modules has a port for introducing concrete or other flowable material into the interior space within the assembled base structure. The modules each have at least one opening therein for fluid communication with a corresponding opening in a second similar module when the modules are assembled together. The hollow interiors of the modules thereby form an essentially continuous interior space which may be filled with concrete to provide an essentially monolithic, solid base for a tower or other structure.

[ 0009 ] The modules may generally be triangular or wedge-like in shape for assembly into a polygonal structure surrounding a central axis. In one aspect, the modules are configured as truncated triangles for assembly into an annular structure that surrounds a central void at the central axis of the base. The void extends the full height of the base and may be filled with concrete to form a solid pedestal for a tower. The resulting pedestal bears directly on the underlying ground surface.

[0010] In another aspect, the invention relates to an assembly that is composed of individual modules which are configured to be assembled into a fluid retention tank having a continuous open interior space extending within the tank spanning multiple modules. The modules each comprise a hollow structure defined by spaced apart upper and lower plates and opposing first and second end walls. The modules are configured for assembly into a structure having an essentially continuous outer skin that encloses an essentially continuous and uninterrupted hollow interior space that extends through all or at least multiple ones of the modules. The joints between the modules may be sealed to prevent leakage of fluid from the interior space. At least one of the modules has a port for introducing water (or other fluid) into the interior space within the assembled base structure. The modules each have at least one opening therein for fluid communication with a corresponding opening in a second such module when the modules are assembled together. The hollow interiors of the modules thereby form an essentially continuous interior space which may be filled with a fluid. The modules may generally be triangular for assembly into a polygonal structure surrounding a central axis. In particular, the modules may be configured as truncated triangles or wedges for assembly into an annular structure that surrounds a central void at the central axis of the base.

[0011] The central void may remain open to form a central recess in the structure. Optionally, the recess may be used to house hoses, valves, pumps or other water control members. Alternatively, the upper and lower openings of the void may be sealed to provide additional water retention.

[0012] The individual modules in all of the above embodiments may have at least one open side and preferably, both opposing sides of the module are open. In this fashion, the modules may be assembled around the central axis with the open sides of the modules being in communication. The interior spaces of the contiguous modules are thus continuous with each other. The assembled base structure thus has a continuous interior space which has a generally toroidal configuration.

[0013] In another aspect, the upper plates of the modules slope downwardly and outwardly away from the central axis to form a generally conical upper surface of the assembled base. This structure permits water to rapidly drain away from the centrally- mounted tower; the can also be horizontal and parallel to the bottom to increase internal volume for ballast and/ or water storage. Alternatively, the upper plates may be essentially horizontal to increase the internal volume within the assembly.

[0014] According to another aspect, the modules form multiple module pairs when placed side by side. Each module pair may be formed from mirror image modules that are contiguous, each comprising a truncated right triangle. The module pairs comprise truncated isosceles triangles when assembled together.

[0015] According to a further aspect, the invention relates to a method for fabricating a base for a tower or a fluid retention assembly. The method includes the steps of providing a plurality of modules, each comprising an essentially hollow structure as described above. The modules are transported to a job site and positioned adjacent to each other such that the openings of adjacent ones of the modules are in fluid communication. In this fashion, the interior spaces of the respective modules define an essentially continuous interior space within multiple ones of the modules. In order to form a base for a tower or other structure, the continuous interior space within the assembly is filled with concrete or other material through at least one of the ports in the modules to form a solid base. When the modules comprise a concrete shell and are filled within concrete, the resulting base consists of a monolithic structure. However, the interior of the assembly need not necessarily be filled with the same material as the outer shells of the modules. The interior of the assembly is preferably filled with a solid material (such as concrete) when the assembly comprises a base for a tower. In order to form a fluid retention assembly, the interior space may be sealed to prevent leakage of fluid from the hollow interior.

[0016] In one aspect, the modules are configured as truncated triangles or wedges and are assembled around a central void at the axis. The void maybe filled with concrete to form a solid pedestal for a tower or other structure. A structure may be fastened to the base with anchor bolts that are anchored within the central pedestal.

[0017] In another aspect, at least one tensioning cable extends peripherally around said assembly to apply a radial inward force when tensioned. The tensioning cables may be inserted within bores within the modules, for example within the outermost wall thereof.

[0018] Directional references as used in the present specification, such as "upright", "horizontal", "vertical" and the like are used herein purely for convenience and description. It will be evident to the person skilled in the art that embodiments of the present invention maybe used in various orientations. Furthermore, any dimensions, construction materials and other manufacturing or fabrication details presented herein, unless otherwise specified, are intended merely by way of illustration and are not intended to limit the scope of the invention in any respect. For convenience, the assembly according to the invention is described herein by reference to the base being situated on a horizontal surface for supporting a vertical tower.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure l is a perspective view of an embodiment of the present invention, showing partially in transparency in order to show internal structure.

[0020] Figure 2 is a plan view from above of the embodiment of Figure l. [0021] Figure 3 is a cross-sectional view along line 3-3 of Figure 2.

[0022] Figure 4 is a cross-sectional view, showing an alternative embodiment of a portion of Figure 3 as shown in the portion circled with a dotted line in Figure 3.

[0023] Figure 5 is a perspective view of a further embodiment of the invention, consisting of an assembly of modules configured to provide a water-retaining function.

[0024] Figure 6 is a plan view of the embodiment of Figure 5.

[0025] Figure 7 is a sectional view along line 7-7 of Figure 6.

[0026] Figure 8 is a perspective view of a module pair of the embodiment of Figures 5-7.

[0027] Figure 9 is a perspective view of a further embodiment. DETAILED DESCRIPTION

[0028] Figures 1-3 illustrate an embodiment of the present invention consisting of an octagonal base assembly 10 for supporting a large structure such as the tower of a wind generator or turbine (not shown). The terms "wind generator" and "wind turbine" are used interchangeably herein and refer generally to a large tower-supported structure that normally includes a horizontal or vertical-axis wind turbine. It will be seen that the present base may be used to support a variety of large towers or other structures that are supported on a relatively large and massive base.

[0029] Base 10 consists of a regular polygon having a central vertical axis "a" with multiple wedge-shaped modular segments 12A and 12B arranged around axis a. Base 10 thus comprises multiple base modules assembled into a unitary structure. Modules 12A and B may be fabricated at a concrete forming facility and then transported to a remote job site where they are initially assembled into a base assembly. Modules 12A and B may be fabricated from precast, reinforced concrete.

[0030] In the present example, base 10 has an octagonal footprint, as seen in Figure 2. Base 10 is assembled from 16 modules, consisting of 8 module pairs 14, each module pair 14 is in turn composed of a pair of modules 12A and B. Module 12A is a truncated right triangle (in plan view) and module 12B is a mirror image of module 12a. Modules 12a and b are thus arranged in side-by-side abutting configuration to form a module pair 14. In plan view, module pair 14 is a truncated isosceles triangle. A total of 16 modules 12a and b are thus assembled into an 8-sided annular structure 10 that surrounds a central space or void 40. It will be seen that other geometric configurations are possible, with resulting variations on the number of modules.

[0031] Modules 12A and 12B each comprise a hollow open-sided shell. As best seen in Figure 3, module 12A is composed of a flat floor 18, an opposing upper plate 19, an inner end wall 20 and an opposing outer end wall 22. A horizontal axis "b" extends between the inner and outer end walls 20 and 22. When modules 12 are assembled into base 10, the respective axes "b" thereof project radially outwardly from central axis a, as seen in Figure 2. Inner wall 20 is greater in height relative to outer wall 22, whereby upper plate 19 slopes downwardly from wall 20 to wall 22. Module 12A further comprises opposing open sides 24 and 26 whereby module 12A has an essentially tubular structure which is open at the respective sides 24 and 26. As mentioned, the configuration of module 12B is a mirror image of module 12A.

[0032] One or both of modules 12A and 12B includes a port 30 within upper plate 19 adjacent to end wall 20, for introducing liquid concrete into the interior of the assembled base 10. It will be seen that not all of modules 12 require a port 30 in order to introduce concrete in the interior of the assembled base 1, since the respective modules are in fluid communication when assembled which permits concrete to flow throughout the assembled structure 10. Port 30 should be at or close to the uppermost area of interior space 16 to allow concrete to fill essentially the entirety of interior space 16.

[0033] Modules 12 are assembled in an annular or toroidal configuration consisting of contiguous module pairs 14, as seen in Figures 1 and 2. In this regard, modules 12A and B are assembled into structure 10 whereby the respective open sides 24 and 26 of adjacent modules communicate with each other to form an essentially torus-shaped internal space 27 that extends fully around base assembly 10 and which is continuous and uninterrupted within the interior of assembly 10. The respective outer walls 22 face outwardly to form the 8-sided perimeter of assembly 10. Inner walls 20 face inwardly towards axis A and define the walls of void 40, which forms an eight-sided structure centered around central axis a. Void 40 is open at its top and bottom, at lower and upper openings 35 and 37 respectively.

[0034] As will be discussed in more detail below, void 40 is filled with concrete as a step during assembly and fabrication of base 10 from multiple modules 12A/12B. When void 40 is thus filled with concrete, there is provided a central, solid pedestal 42 that directly underlies a tower or other structure supported by base 10.

[0035] Multiple reinforcement bars (rebars) 32 and 34 are embedded within floor 18 and upper plate 19 respectively. Portions of bars 32 and 34 protrude from the exposed inner edges of floor 18 and plate 19 to project radially inwardly towards axis a within void 40. The protruding portions of bars 32 and 34 become embedded within pedestal 42 when concrete is introduced into void 40 to increase the structural integrity of pedestal 42.

[0036] A circular array of vertical bolts 46 is provided within void 40 for fastening a tower (not shown) or other structure to pedestal 42. Bolts 46 are welded or otherwise fastened to rebars 32 and 34, to secure bolts 46 in position prior to anchoring same in a vertical position within pedestal 42. When void 40 is filled with concrete, bolts 46 become embedded within pedestal 42 and are securely anchored therein. A portion of bolts 46 project vertically upward above pedestal 42. The upwardly projecting portions 48 of bolts 46 arc thus exposed in the fully assembled based 10 and can be threaded to secure a tower or other structure to base 10.

[0037] Upper and lower bores 45a and b may be provided within modules 12, located at the corners where end wall 22 meets upper plate 19 and floor 18 respectively. Bores 45 provide a hollow conduit for threading upper and lower cables 47a and b around the perimeter of the assembled structure 10. This provides post-assembly tensioning of the assembled structure.

[0038] Assembly of base 1 o may be performed by providing eight each of segments 12A and 12B, as described above. Normally, modules 12 are fabricated at a concrete casting or forming facility and shipped to a remote job site. At the job site, the ground surface is suitably prepared and leveled. Modules 12 are then arranged on the ground in a location where the assembled structure 10 will form the base for a tower or the like. For this step, the configuration of the assembled base 10 will depend on the configuration of the modules. In the present example, the sixteen modules 12 can be assembled into an eight-sided base structure 10 composed of eight module pairs 14. Depending on the desired configuration and overall size of base 10, a lesser or greater number of modules may be provided so as to vary the overall configuration of base 10, with suitable changes to the angular configurations of modules 12. Segments 12 are arranged in a toroidal configuration as shown in Figures 1 and 2, surrounding central void 40. The open sides 24 and 26 are in communication with each other whereby an open interior space 27 is defined that extends through all of modules 12. Interior space 27 is fully enclosed apart from ports 30 and is continuous around base 10.

[0039 ] Modules 12A and 12B may be installed on shim blocks or bearing blocks 50, so as to elevate floor 18 above the ground surface for leveling of base 10 and to provide a space between the ground surface and floor 18. Shim blocks 50 ma be vertically aligned with end walls 20 and 22.

[0040] Following the initial assembly of modules 12 as described above, the joints between the modules may be sealed with grout to prevent liquid concrete from leaking. As well, cables 47a and b may be inserted into bores 45a and b if required.

[0041 ] Concrete is then introduced into the interior space 27 and void 40. Since void 40 is open to below, some of the liquid concrete flows out from lower opening 35 and spreads beneath floor 18, within the gap formed between the ground surface and floor 18. This generates a mud slab to provide a uniform bearing surface for base 10 on the underlying ground surface. The upper exposed surface of the poured concrete, which is exposed within upper opening 37, is flattened and smoothed. Rebars 32 and 34 and portions of bolts 46 become embedded within the concrete and serve to reinforce the concrete when hardened. Concrete within void 40 hardens to form central pedestal 42. When thus entirely filled with concrete and hardened, base assembly 10 forms an essentially monolithic reinforced concrete structure.

[0042] Following pouring of concrete, cables 47a and b are tensioned to apply a stress to structure 10 that is directed radially inwardly towards axis a.

[0043] Depending on the application, additional internal reinforcement may be provided within void 40 and/or interior space 27. [0044] After the concrete has sufficiently hardened and cured, a tower (not shown) may be positioned on the central pedestal 42 and secured to this by anchor bolts 46, which are fastened to the tower by conventional means.

[0045] Figure 4 shows an optional caisson 60 that may be provided to improve the structural performance of base 10. Optionally, caisson 60 is housed in an elongate housing 62, anchored to extend downwardly from floor 18 of one or more of modules 12. Housing 62 may comprise a cardboard tube such as a Sonotube™. Preferably, as shown in Figure 4, housing 62 protrudes at an outward angle from the vertical, so as to splay outwardly relative to axis a. A caisson cage 64 formed from rebar material is positioned within housing 62, extending into space 16 within modules 12. Housings 62 extend through lower openings 66 within floor 18 whereby concrete introduced into space 27 fills housing 62. Caissons 60 may be installed within openings cored into the underlying ground during the installation stage. The interior of housing 62 communicates with interior space 16, such that when modules 12 are filled with concrete, concrete flows into housing 62 whereby caissons 60 are filled with concrete.

[0046] An uppermost portion of caisson cage 64 extends into space 27 within modules 12.

[0047] An opening 68 is provided within upper plate 19, aligned with lower opening 66 to allow caisson 60 to be installed in module 12 prior to the step of pouring concrete. Upper and lower openings 66 and 68 may be pre-formed, or made on-site with an auger. When concrete is poured into interior space 27, liquid concrete flows through lower opening 66 around rebar cage 64, thereby forming a solid, reinforced caisson structure when the concrete hardens.

[0048] According to a further embodiment as seen in Figures 5-8, a modular structure 100 is provided for impounding water or other fluid. References herein to water are understood to apply to other fluids, with appropriate modifications as known to the art. Structure 100 may be put to a variety of uses such as being used to impound runoff water, storage of irrigation water or agricultural chemical solutions, as well as other applications that require either short or long term retention of a fluid. Structure 100 is composed of multiple modules 112. [0049] Structure ιοο may be fabricated and transported as individual modules 112 which are then assembled into the finished structure loo in a location which can be remote from the fabrication plant. The configuration of structure loo is similar to structure ιο and consists of a multi-sided annular structure. However, in one version structure loo optionally is not provided with a central solid pedestal when assembled. Structure ιοο comprises a ring-shaped array of modules 112A and 112B, each of which has a generally similar configuration to base modules 12A and 12B when seen in plan view. However, in order to increase the interior volume of the structure, modules 112 may have horizontal rather than sloping upper plates.

[0050] Each of modules 112A and B comprises upper and lower plates 214 and 216 and opposing inner and outer end walls 218 and 220 respectively, as described below. The respective plates and walls define an interior space 116. The respective (opposing) sides 122 of modules 112 are open. When modules 112 are assembled into structure 100, the open sides 122 thereof communicate whereby the interior space of structure 100 consists of an uninterrupted, continuous, torus-shaped space 222 for storing water. The interior surfaces of modules 112A and B may be lined with a waterproof material 114 such as a membrane or a waterproof coating. Furthermore, one or more of modules 112A and B is provided with one or more water inlet ports 115 (see Figure 7), which may optionally be fitted with a valve or other flow control device, not shown, or alternatively a removable cover, not shown. Port 115 is located within upper plate 214. Port 115 may also provide an outlet for water, which can be pumped or otherwise withdrawn from the interior of structure 100. Alternatively, one or more separate outlet ports (not shown) may be provided at a suitable position on structure 100. The outlet ports may be provided with a valve, removable cover or other flow control device, not shown.

[0051 ] As best seen in Figures 7 and 8, modules 112A and B have essentially rectangular cross-sectional configurations when viewed along axis b. The upper and lower surfaces of modules 112A and B are defined by flat, parallel, horizontal upper and lower plates 214 and 216 respectively. Plates 214 and 216 join with inner and outer vertical walls 218 and 220 respectively. The truncated triangle configuration of modules 12A and B is maintained in modules 112A and B, when seen in plan view. Thus, plates 214 and 216 have essentially identical truncated triangular configurations in plan view. The box-like configuration of modules 112A and B increases the interior space 222 within structure 100. This can provide additional interior space for water retention or loose fill, depending on the use of the assembled structure.

[0052] Structure too may be fabricated and assembled in a similar fashion as base 10. In order to prevent leakage, the joints between modules 112A and B are sealed with a suitable sealant.

[0053] Modules 112 may be secured together within assembled structure 100 by means of upper and lower tensioning cables 47a and b as described above and similar to the arrangement shown in Figure 3, which applies a radially-inward tensioning force to securely retain structure 100 in its assembled configuration.

[0054] Central void 140 provides additional water storage capability

independently and isolated from the interior space 222 of assembly 100. For this purpose, the lower opening of void 140 is sealed with a floor plate 215, consisting of a concrete plate that is inserted within void 140 after assembly of structure 100. A sealant may be applied around the edges of plate 215 to prevent leakage. The upper opening of void 100 is capped with an upper plate 217, which may also be sealed around its edges, to fully enclose void 140 such that fluid may be stored therein. A port 219 within plate 217 permits void 140 to be filled or emptied.

[0055] It will be seen that assemblies 10 and 100 may be suitably dimensioned and configured to meet a wide variety of applications. Depending on the application, the overall dimensions may be scaled up or down and the configuration altered from that depicted herein. As such, any dimensions presented herein shall be taken as merely a representative example and shall not be considered to limit the scope of the invention in any respect.

[0056] Figure 9 illustrates a further embodiment, which is similar in

configuration to the embodiment of Figures 5 to 8. According to this embodiment, multiple modules 314 are provided that are similar in structure to the modules described above for Figures 5-8. One or more of modules 112A and/or 112B is provided with an entry door 300, a window 302 and optionally other openings. The doors and window 300 and 302 are typically provided on the outer end wall 220, although it is also possible for a skylight or other opening to be provided in any other of the respective panels that form the modules. The resulting structure 100 is suitable as a dwelling, storage structure, or other structure that is suitable for entry and exit by individuals. The resulting structure may be put into any use in which individuals enter into the interior of the structure. As such, the interior of assembly 100 comprises a working space that is configured to be suitable for a wide variety of human uses, such as use as a dwelling, storage building etc. The overall interior height is suitable for the selected purpose, for example in the range of 7' -9'. As well, internal barriers within the interior of the assembly can be eliminated or minimized, for example by providing fully open sides 122 of modules 112A/B. Individual modules 112A/B may be sealed with a suitable weathertight seal to protect against the elements.

[0057 ] The scope of the invention should not be limited by the preferred embodiments set forth in the examples but should be given the broadest interpretation consistent with the description as a whole. The claims are not to be limited to the preferred or exemplified embodiments of the invention.

Claims

CLAIMS:

1. A hollow assembly comprising a plurality of modules configured for forming a continuous assembly, each of said modules comprising a hollow structure defined by spaced apart upper and lower plates and opposing first and second end walls, at least one of said modules having a port for introducing a flowable material into the interior of said modules, said modules each comprising at least one opening and being configured whereby when assembled, said openings are each in fluid communication with a corresponding one of said openings in a second of said modules when contiguous with each other whereby an essentially continuous interior space is defined within said assembly for filing with said flowable material.

2. The assembly of claim 1 wherein said modules are generally triangular for assembly into a polygonal assembly surrounding a central axis.

3. The assembly of claim 2 wherein said modules are configured as truncated triangles for assembly around a central void at said axis, wherein said void is configured for filling with a solid material to form a pedestal.

4. The assembly of any one of claims 1 to 3 wherein the openings in said modules comprise at least one open side thereof.

5. The assembly of claim 4 wherein opposing sides of said modules are open, whereby said modules are configured for assembly around a central axis with the open sides of the modules being in fluid communication when assembled whereby the interior space within said assembly is continuous and generally toroidal in configuration.

6. The assembly of any one of claims l to 5 wherein the flowable material comprises concrete.

7. The assembly of any one of claims 1 to 6 wherein said modules comprise precast concrete.

8. The assembly of any one of claims 1 to 7 wherein said plurality of modules comprise multiple module pairs, each module pair comprising mirror image configurations wherein each of said modules comprises a truncated right triangle, wherein said module pairs comprise truncated isosceles triangles when assembled in side by side abutting relation.

9. The assembly of any one of claims l-to 8 wherein at least one of said modules further comprises a caisson protruding downwardly from said structure, said caisson comprising a housing having an interior space in communication with the interior space of said base whereby concrete introduced into said assembly fills said caisson.

10. The assembly of any one of claims 1 to 9 further comprising at least one tensioning cable extending peripherally around said assembly to apply a radial inward force when tensioned.

11. The assembly of any one of claims 1 to 10 wherein at least one of said modules comprises an entry door or a window.

12. A method for fabricating an assembly, comprising the steps of providing a plurality of modules each comprising an essentially hollow structure defined by spaced apart upper and lower plates and opposing first and second end walls, at least one of said modules having a port for introduction of a flowable material into the interior of said modules, said modules being configured whereby when assembled, said modules each comprise at least one opening therein, positioning said modules adjacent to each other whereby the openings of adjacent ones of said modules communicate to define an essentially continuous interior space within multiple ones of said modules, and filling said continuous interior space with said flowable material through said at least one port.

13. The method of claim 12 wherein said modules are generally triangular and are assembled into a polygonal assembly surrounding a central axis.

14. The method claim 13 wherein said modules are configured as truncated triangles and are assembled around a central void at said axis, wherein said void is filled with concrete to form a pedestal.

15. The method of claim 12 wherein the openings in said modules comprise at least one open side thereof and said modules are assembled in side by side relationship whereby the open sides thereof communicate with each other.

16. The method of claim 15 wherein opposing sides of said modules are open, whereby said modules are assembled around a central axis with the open sides of the modules in communication whereby the interior space within said assembled structure is continuous and has a generally toroidal configuration.

17. The method of any one of claims 12 to 16 wherein the flowable material comprises concrete.

18. The method of any one of claims 12 to 17 wherein said modules arc fabricated from precast concrete.

19. The method of any one of claims 12 to 18 wherein said plurality of modules comprises multiple module pairs, each module pair comprising mirror image configurations each comprising a truncated right triangle, wherein said modules are assembled into module pairs that each comprise a truncated isosceles triangle, and said module pairs are arranged around a central axis.