Floating Buildings
A floating base (22) for a building, the base (22) comprising at least one buoyant basement unit (30) defining a basement level, and a reinforced concrete transfer slab (32) atop the or each basement unit (30). The basement level provides habitable or functional space for the building, and the transfer slab (32) has at least one access opening giving access to the basement level. Preferably, the base comprises at least two buoyant basement units, wherein each of the basement units is independently buoyant for assembly with at least one other basement unit during construction of the base, said basement units thereby assuming a final position in which said units are closely adjacent or in contact to define a basement level comprising two or more of said units. The invention also extends to a method for constructing a floating base for a building, and a method for launching a buoyant basement unit.
The present invention relates to floating buildings. In particular, but not exclusively, the invention relates to a buoyant basement structure for a floating building, and a method for constructing such a structure.
BACKGROUND TO THE INVENTIONIn modern urban environments, the development and construction of large buildings for residential, commercial, leisure or industrial use can often be beset with problems.
For example, suitable land for development can be difficult to find. In many cities, large pieces of development land seldom become available, which can restrict the choice of location. However, particularly for commercial developments such as hotels, location is an extremely important factor. Even if a suitably-sized site in an appropriate location can be identified, the cost of the land may be prohibitively high.
In most cases, a site will have been developed previously. Consequently, existing buildings on the land may need to be demolished, and existing services and underground structures (such as drainage pipes, sewers, service ducts, electricity and gas supplies) may need to be preserved or re-routed.
The above problems have led to the use of bodies of water as development sites. Often, cities are located adjacent to rivers, lakes, or the sea. In many of these cities, the area close to the waterline or shoreline has become highly desirable and attractive, particularly for high-value commercial or residential development. Former port areas such as docks may be particularly valued.
One approach to building on bodies of water is to re-claim land. In other words, an area of water is converted to land by drainage, infilling or other means, and the land is subsequently built upon. However, land reclamation is expensive, permanent, and dramatically alters the environment. In particular, land reclamation may remove particularly attractive waterfront. Consequently, land reclamation is not suitable for many developments.
An alternative approach is to build on raised decks or platforms supported on structures which are anchored or set in to the river, lake or sea bed. Examples include buildings constructed on piers, and homes built on stilt-like pillars. In these cases, the platform, and hence the base of the building, must be relatively high above the mean waterline, so as to ensure that the building remains above the water. As a result, a part of the anchoring and supporting structure is often visible beneath the building, which can be unsightly. Furthermore, the weight of the building is limited to that which can be borne by the supporting structure.
A still further approach is to design or adapt a boat or similar vessel for commercial or residential development. Such vessels are usually semi-permanently moored in a suitable location adjacent to land, and access and services are connected to the vessel from the shore, river bank or quayside. Examples include houseboats, prison ships, and the adaptation of cruise ships or other vessels for use as floating hotels or entertainment venues.
Such vessels are, however, inflexible in many ways. For example, the internal architecture of an adapted vessel may be difficult or costly to change, so that the layout of the development is compromised compared to a new-build development. Similarly, the external appearance of the vessel usually remains identifiable as a boat or ship, which will be inappropriate for many developments. Furthermore, the size and weight of the development is dictated by the underlying vessel and is therefore subject to the engineering constraints of boat-building rather than land-based construction. This can restrict the permissible size of vessel-based developments, as can the difficulty of fitting or manoeuvring a large vessel in a confined space.
Floating or floatable buildings, which are not based on vessels, are also known. For example, U.S. Pat. No. 6,199,502 describes the use of connectable concrete flotation modules with polystyrene cores to create a floating pontoon on which structures can be supported. The flotation modules are designed to be transportable by land vehicles, so that a large number of modules are required to create a floating platform of modest size, and the weight that can be supported by the platform is limited.
In other examples, houses and other buildings which are built on areas susceptible to flooding may include buoyant elements which serve to lift the building when the water level rises. In this way, flooding of the building is avoided. For instance, U.S. Pat. No. 5,647,693 describes a floatable building having a watertight concrete basement of unitary construction which provides buoyancy in the event that the site of the building is flooded. As in a conventional building with a basement, the walls of the basement structure support the floor joists and walls of the building above. This limits design freedom and compromises access to the basement. The basement is constructed at the site of the building, and remains in place after construction until floodwater raises the building.
SUMMARY OF THE INVENTIONAccording to a first aspect of the present invention, there is provided a floating base for a building, the base comprising at least one buoyant basement unit defining a basement level, and a reinforced concrete transfer slab atop the or each basement unit. The basement level provides habitable or functional space for the building, and the transfer slab has at least one access opening giving access to the basement level.
In one embodiment, the floating base comprises at least two buoyant basement units, wherein each of the basement units is independently buoyant for assembly with at least one other basement unit during construction of the base, said basement units thereby assuming a final position in which said units are closely adjacent or in contact to define a basement level comprising two or more of said units.
In this way, the basement level advantageously provides accessible and usable space, which may be enhanced by windows for light and ventilation. Furthermore, by virtue of the modular construction of the base, large floating buildings with accessible space in the base can be readily constructed.
In one embodiment, the floating base comprises a plurality of ties, each tie extending partly within the transfer slab. The ties may be connected to the reinforcement of the transfer slab.
Preferably, the ties extend from one or more basement units into the transfer slab, so as to securely connect the transfer slab to the or each basement unit. The ties may, for example, be cast into one or more basement units during construction of said units, or may be bolted or otherwise affixed to the or each basement unit.
Optionally, the ties may extend from the transfer slab into one or more basement units. In this case, the ties may be inserted into holes drilled in one or more basement units, and the ties may be retained in the holes by an adhesive filler, such as a resin grout or mortar.
Where a part of a tie extends within a basement unit, that part of the tie is approximately 400 mm to 750 mm in length. Preferably, the ties comprise reinforcing bars.
The transfer slab preferably comprises a lightweight reinforced concrete slab. For example, the transfer slab may include an array of voids, optionally formed by an array of void formers. In this way, the mass of the floating base can be kept to a minimum, and the centre of gravity can be low in the base so as to provide stability to the base.
Advantageously, the transfer slab comprises a plurality of slab elements. One or more of the slab elements may lie atop one or more basement units. For example, a group of two or more slab elements may lie atop one or more basement units.
Two or more of the slab elements may be adjacent to one another to define a junction therebetween. The slab elements may be connected across the junction by reinforced concrete. When two or more basement units are provided, the junction is optionally positioned where two adjacent or contacting basement units are at their closest.
Junction reinforcement may be provided to reinforce the junction between the slab elements. In one embodiment, the junction reinforcement comprises horizontal reinforcing bars which span the junction between the slab elements. The horizontal reinforcing bars may extend into each of the adjacent slab elements. The horizontal reinforcing bars, when provided, preferably extend at least 900 mm into each of the adjacent slab elements. The junction reinforcement may, alternatively or in addition, comprise reinforcing bars which extend in planes parallel to the junction between the slab elements. The junction reinforcement is preferably connected to the reinforcement of one or both of the adjacent slab elements.
In some embodiments of the invention, at least two basement units are adjacent to one another and a gap is defined therebetween. The adjacent basement units may be connected across the gap by connection means, such as a plurality of connection members attached to the adjacent basement units. The connection members may be arranged in a frame comprising at least two vertically-spaced horizontal members which span the gap between the adjacent basement units. The frame may further comprise two or more vertically-extending brackets for attachment to the respective adjacent basement units. The frame may be attached to the basement units with bolts which extend into walls of the basement units.
When a gap between basement units is present, the gap is preferably at least approximately 300 mm wide. Conveniently, the gap may define a passage for access to the adjacent basement units and the transfer slab. For example, the gap may provide access for divers for inspection, repair or maintenance of the base. Preferably, the gap is approximately 600 mm wide to allow sufficient space for access.
When the transfer slab comprises a plurality of slab elements, one or more of the slab elements may overhang the gap between the adjacent basement units. For example, two slab elements which lie atop the two respective adjacent basement units may meet above the gap. At least one slab element may lie atop both adjacent basement units and extends across the gap.
In some embodiments of the invention, at least two basement units may be in contact. The contacting basement units may be connected to one another by connection means, for example one or more connection members which extend through adjacent walls of the contacting basement units. The connection members may comprise threaded bars and associated nuts which clamp the contacting basement units together.
One or more basement units may include one or more window openings for receiving windows, for example to provide natural light and/or ventilation to the basement level. When windows are provided, the transfer slab may conveniently form a lintel above the or each window opening, so that no additional lintel is required. The or each window opening may be at least 200 mm above the water line in use of the base.
The floating base may comprise a breakwater attached to the exterior of one or more basement units. Preferably, the breakwater is located just above the waterline in use of the base. In one arrangement, the breakwater forms a walkway around a part or all of the base.
The floating base may comprise guide means for preventing horizontal movement of the base. The guide means may comprise locating means which are fixed relative to the body of water, and engagement means arranged to engage with the locating means. The engagement means may, for example, comprise rollers arranged in rolling contact with the locating means, or sliders arranged in sliding contact with the locating means.
The locating means may comprise piles set into the bed of the body of water in which the base floats, and conveniently the piles house apparatus for extracting heat from the bed of the body of water for supply to the building, such as ground source heating apparatus.
The basement units are preferably reinforced concrete which, advantageously, is approximately 300 mm thick. However, it is conceivable that the basement units could be formed of other materials, such as steel.
Preferably, the or each basement unit comprises a floor and upstanding walls to define rooms in the basement level. Optionally, the floor is generally rectangular in plan, so that the rooms may be generally cuboidal.
One or more basement units may comprise insulating means to insulate rooms of the basement level. The insulation may be carried on internal surfaces of the walls. Plasterboard or similar finishing materials can, if desired, be affixed to internal surfaces of the walls of the basement level.
When of reinforced concrete construction, the walls of a basement unit can be made by casting concrete into a formwork mould which defines the shape of the wall. Typically, the formwork comprises plywood shuttering supported on scaffolding. However, in another embodiment, one or more of the walls comprises parallel wall panels spaced from one another to define a core region of the wall. Advantageously, the wall panels comprise pre-cast concrete panels, which can conveniently be manufactured off-site. In this way, the requirement to use formwork to define the shape of the walls can be reduced or eliminated and the time required for constructing the basement units on site is reduced. The core region of the wall is preferably filled with reinforced concrete to provide the necessary strength, although it is conceivable that a lightweight filling material could be used in some applications.
The floating base is particularly advantageous in providing a load-bearing platform to support the weight of a superstructure atop the base. Accordingly, in a second aspect, the invention extends to a floating building comprising a floating base in accordance with the first aspect of the invention, and a superstructure atop the floating base. The transfer slab provides a load-bearing platform to distribute the weight of the superstructure across the or each basement unit.
The floating building may comprise anchoring means to anchor the superstructure to the transfer slab. The anchoring means may, for example, comprise bolts set in to the transfer slab.
The floating base provides a mechanically uniform platform upon which a superstructure of substantially any design and construction can be built. The weight of the superstructure is distributed across the base by the transfer slab, so there need be no correspondence between the position of the load-bearing parts of the superstructure and the position of features within the basement structure. Thus, the present invention offers a flexible and adaptable way of constructing floating buildings.
Accordingly, the superstructure may be positioned centrally on the transfer slab, or alternatively the superstructure may be positioned off-centre with respect to the transfer slab. In either case, the superstructure may have walls or columns that are misaligned with walls of the basement units.
The floating building may further comprise ballast means arranged so that the transfer slab is substantially horizontal. In this way, if the mass of the superstructure is positioned off-centre with respect to the transfer slab, the floating building can be arranged to be level. The ballast means may, for example, comprise ballast weights housed within the superstructure or the floating base or, when two or more basement units are provided, one or more of the basement units may have a large mass relative to the remainder of the basement units to provide the ballast means.
As well as providing support for the superstructure, the transfer slab can act as a fire barrier. Thus, if a fire were to break out in the basement level, unlike an open-framed load bearing structure, the transfer slab would act to slow passage of fire up into the superstructure. Consequently, the basement level can be arranged to house plant for the building, such as equipment associated with electricity generation, metering or distribution, gas supply, water treatment, waste processing and so on.
According to a third aspect of the invention, a method is provided for constructing a floating base for a building. The method comprises assembling, in a body of water, one or more buoyant basement units to define a basement level, said basement level being capable of providing habitable or functional space for a building to be constructed on the base, and casting a reinforced concrete transfer slab across the tops of the or each basement unit while maintaining access to the basement level through the transfer slab.
Advantageously, the method further comprises arranging reinforcing means across the tops of the basement units, and casting the transfer slab so as to incorporate the reinforcing means.
A preferred expression of the method comprises assembling, in the body of water, at least two independently-buoyant basement units closely adjacent to or in contact with one another to define a basement level comprising two or more of said units. By virtue of this method, large floating bases can be constructed for substantially any size of building.
Conveniently, the method comprises arranging the reinforcing means by placing slab elements having a matrix of reinforcing bars across the top of the or each basement unit.
The transfer slab may be cast so as to incorporate reinforcing means extending from the or each basement unit. The reinforcing means of the transfer slab may be connected to the reinforcing means extending from the or each basement unit. Each slab element may comprise a slab base having cut-outs for accepting the reinforcing means extending from the or each basement unit during placing of the slab elements, in which case the slab base is preferably pre-cast before construction of the building, and the cut-outs are optionally formed during manufacture of the slab element.
The method may comprise inserting reinforcing bars into the or each basement unit through the slab elements, and may further comprise forming holes in the or each basement unit for insertion of the reinforcing bars. Each slab element may comprise a slab base and the method may further comprise forming holes in the slab base for insertion of the reinforcing bars.
The holes may be formed after the slab elements are placed across the top of the or each basement unit. Preferably, the reinforcing bars are inserted in the basement units to a depth of at least 300 mm. The reinforcing bars may be fixed in the holes using an adhesive filler. If the slab elements include an array of void formers, the method may further comprise removing one or more void formers for insertion of the reinforcing bars.
In these ways, the transfer slab can be solidly connected to the or each basement unit by way of internal reinforcing bars. In other words, the floating base can, if desired, be made as a unitary reinforced concrete structure to provide strength and stability.
The method may further comprise placing additional reinforcing means in a junction between two adjacent slab elements, in which case the additional reinforcing means are preferably connected to the reinforcing bars of the slab elements.
Where two or more basement units are assembled in the body of water, the method may comprise connecting the basement units to one another before casting the transfer slab. For example, the method may include arranging connection members to connect the basement units, such as bolting the connection members to the basement units, and/or inserting the connection members into the basement units.
The method may comprising arranging panels in a parallel spaced-apart configuration to construct walls of a basement unit. Optionally, the method further comprises filling the space between the panels with concrete.
It will be appreciated that the floating base and, correspondingly, the basement units can be large in size and weight. The method described above advantageously allows for a modular construction of the base, so that a large base can be constructed from a number of smaller basement units, sized appropriately for manufacturing and transportation. However, it is desirable to provide a method for launching large basement units.
Accordingly, in a fourth aspect of the present invention, a method for launching a buoyant basement unit is provided. The method comprises constructing the basement unit on a supporting surface above a plurality of liftable support members, lifting the support members against the basement unit by means of the support members, lifting the basement unit from the supporting surface to an extent sufficient for the basement unit to be moved across the supporting surface, and moving the basement unit on the support members to float in a body of water.
Preferably, the support members are rollers, which optionally rotate around roller axes arranged generally parallel to one another and perpendicular to the direction of movement of the basement unit. In this way, the roller axes may define a path from the surface to the body of water. Accordingly, the roller axes preferably lie generally parallel to the periphery of the body of water. The support members may also, or alternatively, be sliders.
The support members may be lifted by hydraulic or pneumatic means. For example, the method may comprise lifting the support members by inflating air jacks. The basement unit may be lifted clear of the supporting surface.
The method may comprise moving the basement unit using a water craft or a land vehicle. Preferably, however, the method comprises using both a water craft and a land vehicle in a coordinated manner to move the basement unit. The method may include towing the floating basement unit to a construction site after launching.
Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which like reference signs are used for like features and in which:
In this example, the building is arranged to provide hotel facilities, including bedrooms, bathrooms, communal areas such as leisure facilities and restaurants, and service areas such as kitchens, laundries and plant rooms. Additionally, access routes between the various rooms and spaces are provided.
Although the example of a floating hotel will be used throughout the remainder of this description, it will be appreciated that such a building could be used for substantially any function, such as residential accommodation, offices, shops, storage, industry and so on, and that the building could house a number of different functions.
In the present example, the superstructure 20 contains a majority of the rooms, access routes and other areas. However, some of the rooms are accommodated within the basement structure 22. At least part of the basement structure 22 therefore provides an accessible, habitable space that is useful for a function other than mere void space or providing buoyancy. For example, the basement structure 22 may house offices, plant rooms and storage rooms.
Referring additionally to
When the basement units 30 are placed into the water 24, the weight of the basement unit 30 is balanced by buoyancy forces due to the displaced water. Consequently, the basement units 30 float in water, and a portion of each semi-submerged basement unit 30 remains exposed above the water line (labelled ‘W’ in
Each basement unit 30 is designed so that the top faces 40 of the basement units 30 all lie in the same plane at a desired height above the water line. Additional ballast weight (not shown) may be added to some or all of the basement units 30 to achieve the correct height of exposure above the water line.
As shown in
The transfer slab 32 is a lightweight reinforced concrete slab, for example of the type marketed under the registered trade mark BubbleDeck. The slab 32 contains a plurality of void formers 42, in the form of hollow plastic spheres, arrayed within a lattice of reinforcing bars (not shown in
The transfer slab 32 is permanently attached to each of the basement units 30. The connections between a basement unit 30 and the transfer slab 32 consist of reinforcing bars 44 which extend upwardly from the side walls 36 of the basement unit and into the transfer slab 32. Furthermore, the concrete of the transfer slab 32 is cast directly onto the top faces 40 of the basement units 30 to form the connections. In this way, the transfer slab 32 and the basement units 30 can be considered as a continuous reinforced concrete basement structure.
To afford access to the basement spaces 38, openings (not shown in
As shown in
Pile guides 48 are attached to the outer surface of the basement structure 22, just above the water line. As is conventional, each pile guide 48 comprises one or more rubberised rollers (not shown) mounted on a galvanized steel frame. The frame of each pile guide 48 extends around one of the locating piles 46, and the rollers bear upon the outer surface of the associated pile 46. In this way, the basement structure 22, and hence the building, can rise or fall to accommodate changes in the water level. However, lateral or side-to-side motion of the basement structure 22 is prevented so that the building remains in the desired position in the body of water 24. It will be appreciated that the access ramps 28 and other connections between the building and the land are arranged to accommodate the rising and falling motion of the building.
It is to be noted that the locating piles 46 do not bear any significant vertical load from the building. Instead, the function of the locating piles 46 and the associated pile guides 48 is to resist lateral forces, for example from wind and from tidal flows or currents, that would otherwise cause the building to drift or rotate, whilst allowing the building to rise or fall in response to changes in the water level. The locating piles 46 may be partially or wholly filled with material such as concrete, sand or ballast to increase their resistance to lateral forces.
The height of the locating piles 46 is chosen to allow the building to rise and fall through the whole range of expected motion, with a suitable safety factor. For example, the top of the locating piles 46 may be one metre higher than the expected maximum water line under flood conditions.
As shown in detail in
The window units 50 are sealed in the openings 52 using silicone sealant. The tops of the window units 50 lie level with the tops of the side walls 36 of the basement units 30, and so the top of each window unit 50 is sealed against the transfer slab 32. It will be appreciated that the window units 50 are not load-bearing. Instead, the weight of the transfer slab 32 and the superstructure 20 is borne by the concrete walls 36 of the basement unit 30 around the window opening 52. The transfer slab 32 thus performs the function of a lintel, and so no separate lintel is required.
The thickness of the window unit 50 is substantially less than the thickness of the basement unit wall 36. A timber window cill 54 or board is provided to cover the horizontal surface of the window opening 52 in the basement unit 36 which would otherwise be exposed.
The inner surfaces of the basement units 30 are lined with an insulation layer 56. In the example shown in
The transfer slab 32 provides a large, flat area upon which the superstructure 20 of the building is supported. Because the transfer slab 32 spans across the basement units 30, the transfer slab 32 spreads the weight of the superstructure 20 over all of the basement units 30 in all directions. Meanwhile, usable and accessible space is provided beneath the transfer slab 32 as described above.
Because the transfer slab 32 presents a structurally homogeneous base for support of the superstructure 20, the basement structure 22 allows a wide choice of methods for construction of the superstructure 20. For example, the superstructure 20 could be of conventional blockwork or brickwork construction, or it could have a structural steel or timber frame with closed non-load bearing panels of timber, steel or glass. Parts of the building could be clad with timber, steel, glass, or any combination of these or other materials. The roof structure may be pitched or flat or, as shown in
In the examples shown in
The wall structure in this example is of timber construction, and is formed as a multi-layer sandwich structure. Two 15 mm thick dry lining boards 64, 66 (such as those marketed under the registered trade mark Fermacell) are positioned approximately 140 mm apart. A first one 64 of these boards forms the internal surface of the wall, while a second one 66 of the boards lies approximately half-way through the wall. The gap between the boards is filled with insulation 68, such as Rockwool. The wall is completed by a 150 mm thick expanded polystyrene insulation layer 70 on the outermost surface of the second dry lining board 66. The expanded polystyrene insulation 70 is finished with a suitable rendering or cladding system 72.
The whole wall lies on top of the damp-proof membrane 62, and the timber frame (not shown in
The dimensions of the superstructure 20 dictate the size of basement structure 22 required. As described above, the basement structure 22 is of modular construction. The size and number of basement units 30 can be varied according to the design and structural requirements of the building. In this way, basement structures 22 can be made to substantially any size and therefore the present invention allows construction of very large floating buildings. For example, buildings of four storeys or more in height are possible.
For stability, the weight of the superstructure 20 should be less than the total weight of the basement structure 22, including the basement units 30 and the transfer slab 32. In this way, the centre of gravity of the building is advantageously low: for example, the centre of gravity may lie at or around the second storey level of the building when the building is four storeys high.
Because the transfer slab 32 acts to distribute the weight of the superstructure 20 over all of the basement units 30, the superstructure 20 need not be located centrally on the transfer slab 32. Furthermore, there need be no correspondence in the position of the load-bearing walls or frame of the superstructure 20 with the position of the basement units 30 beneath the transfer slab 32. Adjustments can be made to the trim of the building by ballasting and/or at the design stage of the basement structure 22.
A ground-source heat system may be installed to provide heating, hot water or both to the building. In the example shown in
Wind turbines may be installed on the roof of the superstructure. For example, in
Part of the basement space 38 within one or more basement units 30 may be devoted to water recycling facilities. For example, the basement structure 22 may house a sewage treatment plant 90, potable water tanks 92, and grey water recycling tanks 94.
A flexible service duct (not shown) is provided to allow connection of services such as gas, electricity, telephone, sewage and water from the land to the building. The service connections within the duct are themselves flexible. For example, for water and gas connections, flexible plastics pipework is employed. In this way, the service supply connections are arranged to accommodate any rising and falling motion of the building.
Construction of a building in accordance with the invention will now be described. In broad terms, construction involves casting the concrete basement units 30 on land, then launching the basement units 30 into the water. The basement units 30 are arranged into the desired configuration and linked together. The connected basement units 30 are then attached to the locating piles 46, which may be placed on site before or during construction of the building itself.
The transfer slab 32 is formed on top of the basement units 30. The building's superstructure 20 is then constructed on the transfer slab 32. Finally, access and service connections from the land to the building are put in place.
Each of the construction steps will now be described in more detail.
Casting of the concrete basement units 30 may be performed by a conventional process. Typically, an area of land large enough to accommodate a basement unit 30 is levelled and prepared. Compaction and reinforcement of the ground may be necessary to support the weight of the basement unit 30, for example by incorporating hardcore and geotextile materials into the earth. A sand blinding layer or sacrificial formwork may be laid over the ground for casting of the bottom surface of the basement unit 30. Once the casting site has been prepared, a matrix of reinforcing bars of an appropriate shape is constructed. The reinforcing bars may be welded or tied to one another to provide a temporarily self-supporting lattice of reinforcing bars. Plywood shuttering is used to define the vertical surfaces of the basement unit 30. Concrete is then poured between and around the reinforcing bars. The shuttering constrains the concrete so that the correct shape is formed. After pouring, the concrete cures over time. Typically, the design strength of the concrete is reached after around 28 days of curing.
Usually, each basement unit 30 is cast in a multi-stage process, in which concrete is first poured to form the base or floor 34 of the unit 30 and subsequently poured to form the upstanding walls 36. In this way, the initially-cast base 34 can support and distribute the weight of the walls 36. Similarly, and particularly if window or other openings are provided in the walls of the basement unit 30, concrete may be poured to form the walls 36 in two or more steps.
In some embodiments of the invention, a number of upwardly-extending reinforcing bars, sometimes known as kicker bars or starter bars, are left exposed above the top face of the walls of each basement unit 30. The end portions of these exposed reinforcing bars may be bent at 90 degrees to the upstanding portion. As will be explained in more detail later, these exposed reinforcing bars form part of the connection between the basement unit 30 and the transfer slab 32.
Once completed and fully cured, the cast basement units 30 must be transferred to the body of water 24 in which the building is to be constructed. A number of possible methods of transferring the basement units 30 will now be described, and it will be appreciated that the most appropriate method for a given building will depend upon the size and weight of the basement units 30, the proximity of the casting site to the body of water 24, and the nature of the bank or shoreline.
If the basement units 30 are relatively small and lightweight, and suitable access is available, a crane could be used to lift the basement units 30 into the water. Such a method would typically be suitable where the mass of each basement unit 30 does not exceed 140 tonnes, although larger-mass units could be lifted where suitable equipment is available.
An alternative approach is to cast the basement units 30 in the base of a dry dock. After curing, the dry dock can be flooded so that the basement units 30 float. The basement units 30 can then be towed to their final positions. This method is suitable when a dry dock which is large enough for the construction of the basement units 30 is available, or when a temporary dry dock can be created, and allows construction of basement units 30 with large mass. If possible, all of the required basement units 30 are constructed at the same time, but otherwise the basement units 30 may be constructed and floated one-by-one or in batches.
As shown in
As shown additionally in
Plywood shuttering (not shown) is arranged over the trenches 102 to cover the roller devices 106 and restore the flat ground level. A sand blinding layer (not shown) is then created over the site, and the basement unit 30 is cast as described above.
As shown in
As shown in
The basement unit 30 is then pushed and pulled towards the water by a land vehicle and a tug boat respectively, which work together to control the motion of the basement unit 30 during launching. As shown in
The launching method shown in
In each possible launching method, it may be necessary to construct the basement units 30 on a site away from the eventual location of the building and then transfer the basement units 30 to the water at that location. In such a case, the basement units 30 could be towed to the construction site by a tug boat or similar vessel. The basement units 30 can be designed to fit through any width or depth restrictions en route from the launch site to the construction site.
Once the basement units 30 are in the correct location, they are connected to one another. Conveniently, anchorage bolts used to attach tow lines for movement of the units 30 are used to make temporary connections. Permanent connections are then made between adjacent basement units 30. The nature of the connections between two basement units 30 depends upon the spacing between the units, as will now be described.
In this case, the basement units 30 are joined together by connecting elements, each of which comprises a galvanised mild steel framework attached to the corners of the basement units 30.
A central connecting element 122 connects all four of the basement units 30 together, and is shown in side sectional view in
Each of the brackets 124 is attached to a corner of a respective basement unit 30 by means of six bolts 128. As can be seen most clearly in
Similar connecting elements 130 are used to connect the corners of two basement units 30 at the outer edges of the basement structure 22. In these cases, the connecting elements 130 comprise two brackets connected by two vertically-spaced horizontal members.
Once the basement units 30 are connected in the desired configuration, the transfer slab 32 is constructed by placing a plurality of pre-fabricated slab elements (such as the aforementioned BubbleDeck) on top of the basement units, and then pouring concrete on to the slab elements to form the transfer slab. In BubbleDeck applications, the slab elements comprise an array of spherical hollow void formers sandwiched between two meshes of reinforcing bars. The lowermost mesh is cast into a 65 mm-thick concrete slab base or ‘biscuit’. A number of arrangements for placing and securing the slab elements onto the basement units 30 will now be described.
As shown in
As shown in
In this way, the reinforcing bars 138 of the basement units 30 extend into the slab elements 136, and can be connected to the reinforcing bar mesh 144 of the slab elements 136 by welding or tying.
Additional reinforcing bars are placed in and around the junction between the slab elements 136. In particular, shear reinforcing bars 140 are placed above and below the void formers of both slab elements 136, and extend from one slab element 136 to the other. Vertical and horizontal link reinforcing bars 142 are also placed around the junction. The shear and link reinforcing bars 140, 142 are joined to the exposed reinforcing bars of the basement units 138, and the mesh reinforcement 144 of the slab elements 136.
A second arrangement, shown in
Additional reinforcing bars are placed in and around the gap between the slab elements 136, in a similar manner to that described with reference to
A third arrangement is shown in
Void formers (not shown in
Vertical holes 146 are then drilled through the slab base 134 of each slab element 136. The holes 146 extend into the walls 36 of the basement units 30. Vertical reinforcing bars 148 are then inserted through the holes 146 in the slab bases 134 and into the basement unit walls 36.
The vertical reinforcing bars 148 are tied or welded to the reinforcing bar meshes 144 of the slab elements 136, and are resin grouted in the holes 146 in the basement unit walls 36. In this example, the holes 146 are 35 mm in diameter and extend to a depth of 400 mm in the basement unit walls 36, and the vertical reinforcing bars 148 are 25 mm in diameter.
As described above, additional shear reinforcing bars 140 and link reinforcing bars 142 are then placed to bridge between the slab elements 136, and the shear reinforcing bars 140 are tied or welded to the reinforcing bar meshes 144 of the slab elements 136. A compressible material 139 such as silicone sealant or mortar grout is inserted between the ends of the slab elements 136 to seal the gap that would otherwise exist.
In all of these arrangements, the resulting structure is an arrangement of basement units 30 which support a platform of slab elements 136. Reinforcing bars 138, 148 extend vertically upwards from within the walls 36 of the basement units 30 into the slab elements 136, and are joined to the reinforcing bar arrangement 144 within the slab elements 136.
The next construction step is to pour concrete on the slab elements 136 to form a uniform, flat transfer slab 32 upon which the superstructure 20 can be built. Typically, the transfer slab 32 will be 360 mm thick. Plywood formwork or shuttering is used to define the edges of the transfer slab 32 and to prevent leakage of concrete during pouring. Shuttering is also used to define openings 150 where they are required in the transfer slab. Gaps between adjacent slab elements 136 may be sealed with mortar, resin grout or a compressible material.
Concrete is poured onto the slab elements 136 in one operation, to a height of approximately 50 mm above the void formers 42 and upper reinforcing mesh 144 of the slab elements 136. The concrete is then vibrated, compacted, levelled and allowed to cure to form the transfer slab 32. Curing agents may be used to speed up the curing process. The top surface 154 of the cured concrete layer can be seen in
Once the transfer slab 32 has cured, the superstructure 20 can be constructed on top of the transfer slab 32. As described above, many construction methods are suitable for building the superstructure 20. In one example, the superstructure 20 is pre-fabricated on land and then craned on to the transfer slab 32 in pieces for assembly and finishing. The superstructure 20 can be held on the transfer slab 32 by any suitable means, such as bolts or mortar. Reinforced concrete connections between the superstructure 20 and the transfer slab 32 may also be provided, in which downwardly-extending reinforcing bars of the superstructure 20 concrete are resin bonded into holes drilled in the transfer slab 32.
It will be appreciated that many modifications and variations of the embodiments described above lie within the scope of the invention.
For example, in the embodiments described above, the basement units comprise reinforced concrete walls constructed by casting concrete over a framework of reinforcing bars. Shuttering is used to define the outer surfaces of the walls, and the shuttering is removed after the concrete has set.
In another variant, the walls of the basement units are constructed using pre-cast concrete wall panels in place of the shuttering. Such construction systems are sometimes referred to as “twin wall” systems.
As in previous embodiments, the floor section 158 is a reinforced concrete slab. In this case, however, the wall 156 comprises an outer panel 160 and inner panel 162 located parallel to and spaced apart from one another to define a 160 mm-thick core region 164 between the panels 160, 162. Each panel 160, 162 is a 70 mm-thick pre-cast concrete panel. During construction of the wall 156, the core region 164 is filled with reinforced concrete.
Some reinforcement in the core region 164 extends from one panel to the other so as to connect the panels 160, 162 and to maintain the desired spacing between them.
Preferably, this connecting reinforcement comprises reinforcing bars (166 in
Some reinforcing bars extend into both the core region 164 of the wall 156 and the floor section 158, so as to create a strong connection between the wall 156 and the floor section 158. In
As shown most clearly in
Referring again to
When the desired length of a basement unit wall exceeds the convenient width of a single pre-cast panel, the wall can be constructed using a number of pre-cast panel sections assembled side-by-side. As shown in plan view in
A connecting element comprising a threaded bar 198 extends across the gap 120 between the two adjacent basement units 30a to connect the basement units 30a to one another. The connecting bar 198 extends through the walls 156 of the basement units 30a. For this purpose, pre-cast holes 200 are provided in the panels 160, 162 of the walls 156, as shown in
A transfer slab support element is also shown in
It is conceivable that the floating base may comprise a single basement unit. Where more than one basement unit is provided, the basement units in a single basement structure may be of different sizes. To ensure the tops of the basement units are arranged to lie in the same plane, substantial additional ballast weight may be provided. The floor or wall thickness of a basement unit may be increased to provide additional ballast weight where necessary.
Where basement units abut one another, access routes between the basement units may be provided by way of openings formed in the walls of the basement units, with silicone sealant or other sealing means provided between the basement units around the openings to prevent water inflow.
Instead of steel piles, other locating means could be used such as concrete piers. Where the situation allows, the locating means on the shore or bank side of the building could be a land-based structure, such as a quay or harbour wall.
The access ramps or bridges may be connected to a walkway or terrace which surrounds the building just above the water line. The walkway forms a barrier which helps to block or diffuse surface motion of the water, such as waves or wash from passing vessels. Similarly, if the access ramps or bridges connect to the building above basement or ground-floor level, then a low-level walkway, accessed via the interior of the building, may be provided just above the water line to act as a wave barrier. In either case, the walkway is preferably connected to the basement units by galvanised steel frame brackets.
Where a walkway is provided close to the water line, boat mooring capstans or similar structures may be provided to enable water craft to moor alongside the structure.
Claims
1.-111. (canceled)
112. A floating base for a building, the base comprising:
- at least one buoyant basement unit defining a basement level; and
- a reinforced concrete transfer slab atop the or each basement unit;
- wherein:
- the basement level provides habitable or functional space for the building;
- the transfer slab has at least one access opening giving access to the basement level;
- the floating base comprises at least two buoyant basement units adjacent to one another with a gap defined therebetween; and
- the adjacent basement units are connected across the gap by connection means.
113. The floating base of claim 112, wherein each of the basement units is independently buoyant for assembly with at least one other basement unit during construction of the base, said basement units thereby assuming a final position in which said units are closely adjacent or in contact to define a basement level comprising two or more of said units.
114. The floating base of claim 112, wherein the connection means comprise a plurality of connection members attached to the adjacent basement units.
115. The floating base of claim 114, wherein the connection members are arranged in a frame comprising at least two vertically-spaced horizontal members which span the gap between the adjacent basement units.
116. The floating base of claim 115, wherein the frame comprises two or more vertically-extending brackets for attachment to the respective adjacent basement units.
117. The floating base of claim 115, wherein the frame is attached to the basement units with bolts which extend into walls of the basement units.
118. The floating base of claim 112, wherein the gap is at least approximately 300 mm wide.
119. The floating base of claim 118, wherein the gap defines a passage for access to the adjacent basement units and the transfer slab.
120. The floating base of claim 119, wherein the gap is approximately 600 mm wide.
121. The floating base of claim 112, wherein at least two of the basement units are in contact.
122. The floating base of claim 121, wherein the contacting basement units are connected to one another by connection means.
123. The floating base of claim 122, wherein the connection means comprises one or more connection members which extend through adjacent walls of the contacting basement units.
124. The floating base of claim 123, wherein the connection members comprise threaded bars and associated nuts which clamp the contacting basement units together.
125. The floating base of claim 112, wherein one or more basement units includes one or more window openings for receiving windows.
126. The floating base of claim 125, wherein the transfer slab forms a lintel above the or each window opening.
127. The floating base of claim 125, wherein at least one window opening provides ventilation to the basement level.
128. The floating base of claim 125, wherein the or each window opening is at least 200 mm above the water line in use of the base.
129. The floating base of claim 112, further comprising a breakwater attached to the exterior of one or more basement units.
130. The floating base of claim 129, wherein the breakwater is located just above the waterline in use of the base.
131. The floating base of claim 130, wherein the breakwater forms a walkway around a part or all of the base.
Type: Application
Filed: May 11, 2009
Publication Date: May 26, 2011
Inventor: Carl R. Nelson (Berkshire)
Application Number: 12/991,774
International Classification: B63B 35/44 (20060101); B63B 5/18 (20060101); B63B 35/38 (20060101);