NZ720615A - A Modular Bearing System - Google Patents

Abstract

ABSTRACT The present invention discloses an apparatus for use in base isolated structures to provide low friction bearings primarily to buildings where a ?oating concrete slab is poured in situ on top of a foundation ratt. The invention is intended to be used in situations where removal of the formwork used to form the ?oating slab is not required or not possible atter the slab has been formed. The present invention provides a plurality of bearing modules which are ?xedly attached to the ?oating slab, each bearing module providing a space through the ?oating ?oor to allow inspection and maintenance of the bearings held by the bearing module, and their replacement if necessary.

Description

A MODULAR BEARING SYSTEM TECHNICAL FIELD The present invention relates to a modular bearing system used to provide a plurality of bearings between two structures. In particular it relates to providing a bearing system whereby the bearing may be inspected and/or replaced in situations where there is limited access to the bearing In particular it may relate to, but is not limited to, situations where the bearing is located between a foundation raft and a floating concrete slab which is poured in situ so that is no ready access to the bearing from the space between the floating slab and the foundation raft.

BACKGROUND ART When constructing structures that include seismic base isolation, typically an isolated ground floor slab is built over a basement foundation so that the base isolators can be placed on top of the walls or columns of the foundation. The basement foundation provides space to erect and remove the formwork to pour the floating slab and to access to the base isolators for inspection and maintenance.

However, the construction of a basement adds cost to the structure and is not required for most light framed dwellings and commercial buildings.

To overcome this problem it is possible to use a foundation raft, typically a concrete slab (although other structures may also be used) above which a floating concrete slab can be poured. Base isolation can be achieved by placing a low friction layer (e.g. two sheets of PTFE) on top of the foundation raft prior to pouring the floating slab on top of the raft.

A drawback of this solution is that significant costs are incurred from the materials used to achieve the low friction layer.

A further problem with this arrangement is that there is often a regulatory, or at least a good practice requirement to inspect / replace the components involved in the base isolation during use, especially following a seismic event.

A recent invention of an apparatus and method (SEISMAT™) for forming a floating concrete slab over a foundation raft allows the formwork to remain in place after the slab has been formed.

SEISMAT™ is a sacrificial formwork for use with weight bearing structures, which is able to support the initial load of the concrete when poured and to gradually transfer the load to the weight bearing structures as the concrete cures. What remains is a low friction layer between the foundation raft and the floating slab. Base isolation bearings may be used in conjunction with SEISMAT™ by locating them on top of the weight bearing structures.

Base isolation systems involving bearings with a reduced thickness are preferred when using SEISMAT™ as a gap of 20-30mm is formed between the floating floor and the foundation raft.

An example of such a base isolation system is a device known as a Flat Sliding Bearing: essentially any device composed of two flat surfaces having good load bearing capacity but low horizontal resistance to motion.

The use of a Flat Sliding Bearing is often combined with other types of base isolation, which may contribute to dumping the seismic energy or restricting the displacements of the components to within an acceptable range, and, above all, to restore the original configuration of the structure following a seismic event.

Another form of base isolation system, commonly referred to as Curved Sliding Bearings, uses a slider having a curved surface which slides over a curved surface attached to the foundation raft. This may provide a restoring force as well as a dumping effect.

The performance of Flat and Curved Sliding Bearings is essentially not dependent on the weight of the superstructure meaning both are suitable for the base isolation of light framed buildings.

However, the requirement for inspection and maintenance remains to be addressed, as the gap between the floating slab and the foundation raft is generally too small to allow access to the bearings.

Furthermore, if the problem related to the accessibility to the sliding bearing is solved, a temporary support would still be required in order to prevent structural damage to the supported floating floor when the bearing is removed (e.g. for examination or replacement).

The objective of the present invention is to address the fore mentioned problems or at least to provide the public with a useful choice.

All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinence of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country.

Throughout this specification, the word "comprise", or variations thereof such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.

DISCLOSURE OF THE INVENTION The present invention discloses an apparatus for use in base isolated structures to provide low friction bearings primarily to buildings where a floating concrete slab is poured in situ on top of a foundation raft. However, this should not be seen as limiting as other uses are also envisaged, for example the invention may be used to provide a bearing on a bridge (e.g. to allow movement of the bridge with respect to the ground due to thermal expansion of the bridge or seismic attack), and between two closely spaced walls.

The invention is intended to be used in situations where removal of the formwork used to form the floating slab is not required (e.g. may remain hidden) or where it is not possible, impractical or inconvenient to remove the formwork after the slab has been formed (e.g. when the floating slab is formed in a building without a basement).

A feature of the present invention is to provide a plurality of bearing modules which are fixedly attached to the floating slab, each bearing module providing a space through the floating floor to allow inspection and maintenance of the bearings held by the bearing module, and their replacement if necessary.

Another feature is that the bearings are held in the bearing module such that bearings may be added and/or removed to the bearing module in such a manner that the load carrying capacity of the bearings in the bearing module may be greater than or equal to the required load bearing at the bearing site, which may improve safety during removal of the bearings for inspection/maintenance.

Yet another feature is that each bearing module provides a plurality of bearing mounts, the number chosen so that one or more relatively small bearings may be held in a single bearing module, the total load bearing capacity of the small bearings being at least the required load bearing at the bearing site.

This feature may allow easier access to, and handling of, each of the one or more relatively small bearings than would be case if a single, relatively large, bearing was used.

The general concept is that for each bearing module, multiple bearing supports may be used and may be combined in an array that allows the removal / substitution of a bearing without causing a loss of total support and/or structural damage. Each bearing module includes at least the number of bearing supports and bearings required to support the load on the bearing at the location of the bearing module, plus one more (redundant) bearing housing (i.e. a housing without a bearing associated with it).

According to one aspect of the present invention there is provided a method of use of a method of use of a modular bearing system for providing a bearing between a first structure and a second structure, wherein the modular bearing system includes a plurality of bearing modules, each bearing module including: a first load bearing member configured to attach to the first structure; a first bearing mount and a second bearing mount each rigidly attached to the first load bearing member, the bearing mounts configured to releasably secure a bearing or a load bearing member, a casing around the first bearing mount and the second bearing mount, the casing configured to provide a space in the first structure through which the first bearing mount and the second bearing mount can be accessed and through which the first bearing can be moved to or from the first bearing mount, the method including the steps a. forming a bearing site by incorporating the bearing module into the first structure such that the first load bearing member is firmly attached to the first structure and the casing extends through the first structure to an outer surface of the first structure; b. locating the first bearing in the bearing module by inserting a first bearing through the space in the casing and through the first bearing mount into the space between the first structure and the second structure so that it is supported on or by the second structure; and c. securing the first bearing in the first bearing mount.

In a preferred embodiment the method includes the step of: d. re repeating steps b to e to add further bearings to the bearing module as needed to provide the required load bearing at the bearing site.

In a preferred embodiment the method includes the steps of: e. passing a second bearing through the casing and the second bearing mount and supporting it on or by the second structure; f. securing the second bearing in the second bearing mount; and g. releasing the first bearing from the first bearing mount and removing it out through the space in the casing.

In a preferred embodiment the method includes the steps of: h. providing a second bearing mount in the bearing module, the second bearing mount configured to releasably engage with a second load bearing member; i. securing the second load bearing member in the second bearing mount and supporting it on or by the second structure; j. removing the first bearing by releasing it from the first bearing mount and moving it through the first bearing mount and out through the space in the casing; k. replacing the removed bearing using steps b to e of claim 1; and l. releasing and removing the second load bearing member from the second bearing mount In a preferred embodiment the first structure includes a floating concrete slab and the second structure includes a foundation raft, wherein the floating concrete slab is poured in situ above the foundation raft.

In a preferred embodiment the bearing module forms part of the formwork for pouring the floating slab.

In a preferred embodiment the bearing module includes a plurality of bearing mounts of which at least two bearing mounts support a bearing.

In a preferred embodiment at least one of the plurality of bearing mounts does not support a bearing or a load bearing member.

An essential feature of the present invention and its use is the provision of a redundant or surplus bearing mount into which a further bearing can be added to take over the load borne by an existing the bearing module as may be required for inspection, maintenance or replacement of an existing bearing in the bearing module. When the further load bearing member is added to the bearing module the load holding of the bearings in the module is increased. This may allow one of the existing bearings to be removed, with the further load bearing member taking up the load of the existing bearing. By repeating the method each of the existing bearings may be removed in turn without compromising the load bearing capacity of the bearing module.

In a preferred embodiment the second load bearing member is a second bearing. However, in other embodiments the second load bearing member includes a structure configured to support a load the same as or greater than that supported by a second bearing, for example as may be supplied by a bolt screwed into the thread of the second bearing mount.

According to another aspect of the present invention there is provided a modular bearing system for providing a bearing between a first structure and a second structure, wherein the modular bearing system includes a plurality of bearing modules, each bearing module including: a first load bearing member configured to attach to the first structure; a first bearing mount rigidly attached to the first load bearing member; a second bearing mount rigidly attached to the first load bearing member; a casing around the first bearing mount and the second bearing mount, wherein the bearing mounts are configured to releasably secure either a bearing or a load bearing member, and the casing is configured to provide a space in the first structure through which the first bearing mount and the second bearing mount can be accessed and through which the first bearing can be moved to or from the first bearing mount.

In a preferred embodiment the first structure includes a floating concrete slab and the second structure includes a foundation raft, wherein the floating concrete slab is poured in situ above the foundation raft.

Reference to a foundation raft throughout this specification should be understood to mean a solid, flat substrate used as a support structure for the floating slab. Commonly the foundation raft will be a fixed slab of concrete, although this should not be seen as limiting.

The present invention may be particularly suited to situations where the gap between the floating slab and the foundation raft is too small to allow ready access to the bearings for inspection, maintenance or removal though the gap.

The floating slab is supported on the foundation raft by a plurality of bearings located at various sites under the floating slab as determined by the engineering requirements for supporting the floating slab.

In a preferred embodiment a modular bearing system is associated with each of the bearing sites between the first structure and the second structure.

The size and nature of the bearing, or bearings, at each bearing site is typically determined as part of the engineering requirements for supporting the floating slab and any associated superstructure. The load may be carried by a single bearing or by a plurality of smaller bearings which together may carry the load of the single bearing.

In a preferred embodiment, the modular bearing system includes a plurality of bearing mounts.

Although a single bearing may be used at each site, it is envisaged that the present invention will provide a cluster of smaller bearings at each bearing site.

Providing a modular bearing system which is designed to engage with a plurality of bearings may provide a number of significant advantages including: replacing a single large bearing with a plurality of smaller bearings may make it easier to handle each bearing as the smaller bearings may have smaller size and weight; one of the plurality of smaller bearings may be removed for inspection/maintenance with the remaining smaller bearings taking the load of the slab at the bearing site, rather than having to remove a single large bearing leaving no load bearing support at the bearing site; the plurality of smaller bearings may all be similar in size and weight, so that they are interchangeable, and there may be manufacturing savings as all bearing loads may be made up by a plurality of identical, modular, bearings; and most importantly, it is likely to be easier to inspect and/or replace a plurality of small bearings, one at a time, rather than a single large bearing.

In a preferred embodiment, in use, at least one of the plurality of bearing mounts does not support a bearing.

Leaving at least one bearing mount without a bearing may allow additional load bearing to be added at the bearing site prior to removal of one to the bearings from its bearing mount. In this manner the appropriate load bearing may be retained at all times during inspection/maintenance of the bearings.

The empty bearing mount may be configured to accept a bearing similar to the bearings in the other bearing mounts, or it could be configured to include a threaded cylindrical hole into which a bolt may be screwed to support the load while maintenance is carried out on the other bearings. On completion of the maintenance the bolt is removed to allow the remaining bearings to function as designed.

In a preferred embodiment the load bearing member includes a plate configured to attach to a surface of the floating concrete slab opposite a face of the foundation raft.

In this embodiment the plate forms a section of the formwork for the floating slab prior to pouring the concrete. The plate may include fasteners, such as a bolt or pin, which may hold the plate in place after the floating slab has been formed.

In a preferred embodiment the casing extends orthogonally away from the plate with a height substantially the same as a depth of the finished floating slab.

In this embodiment, the modular bearing system is used as part of the formwork for the floating slab, with the plate facing the foundation raft and the casing extending away from the plate so that it extends through the floating slab when it is poured. In this way access to any bearing held in the modular bearing assembly may be made from an upper surface of the floating slab. Typically the opening in the casing at the level of the upper surface of the floating slab may be covered with a removable cover.

In some embodiments the casing includes a single sleeve around the two bearing mounts. In these embodiments the casing consists of a single sleeve, for example an open ended cylinder, which is attached at one end to the plate, the sleeve surrounding the plurality of bearing housings included in the bearing module.

In a preferred embodiment the casing includes two sleeves, one above each of the first bearing mount and the second bearing mount.

In a preferred embodiment a sleeve is associated with each bearing mount in the bearing module, each sleeve providing a space allowing access to the enclosed bearing mount and through which a bearing can pass.

In a preferred embodiment the bearing includes either a flat sliding bearing or a friction pendulum sliding bearing.

In a other embodiments the bearing includes a rubber bearing.

In a preferred embodiment the sliding plate (flat or curved) is made with galvanized or stainless steel while the low-friction components are made with PTFE or UHWMPE.

If Flat Sliding Bearings are used then a re-centering force is required. For this purpose conventional Rubber Bearings can be used.

Alternatively, Modular Sliding Bearings located at the perimeter of the foundation can be equipped with pulleys and pre-stressed steel cables, with elastic stretch ability of 3-5%, connected with the foundation raft. The elastic stretch ability of the cables can be used to restrict movements of the bearings within the design limits and restore the bearings to their original positions after a seismic event.

If Curved Sliding Bearings are used then spherical hinges in the Modular Sliding Bearings are required to accommodate the variable angle of contact between the low-friction components and the plates.

A modular bearing system as claimed in any one of claims 8 to 15 including a second bearing retainer configured to releasably attach to a second bearing mount and to locate a second bearing at the second bearing mount.

In preferred embodiments the modular bearing system includes a second bearing mount configured to support a load bearing member capable of supporting a load the same as or greater than that supported by the first bearing.

In some embodiments the second bearing mount includes a threaded cylindrical aperture and the load bearing member is a threaded bolt configured to engage with the thread of the cylindrical aperture.

In other embodiments the load bearing member is a jack.

The present invention may have a number of advantages over prior art formworks and methods, including:  providing a method for producing two concrete slabs, one on top of the other in close proximity, where the slabs are held apart bearings held in a bearing module which is accessible from outside one of the slabs, and where the slabs can move relative to one another with relatively low frictional forces between them;  enabling full accessibility to the low-friction components of the sliding bearings from outside one of the slabs for inspection/maintenance, without the need of resorting to the gap between the floating floor and the foundation raft to access the bearings;  ensuring full accessibility and maintainability to the low-friction components of the sliding bearings without resorting to any temporary support in correspondence of the bearing point during maintenance work.

 Offering a modular geometry able to optimize costs and adapt to the bearing needs of the superstructure.

BRIEF DESCRIPTION OF THE DRAWINGS Further aspects of the present invention will become apparent from the following description, which is given by way of example only and with reference to the accompanying drawings in which: FIGURE 1 – Shows a Modular Sliding Bearing according to one embodiment of the present invention (Top view).

FIGURE 2 – Shows a Modular Sliding Bearing (Flat type) according to one embodiment of the present invention (Perspective).

FIGURE 3 – Shows a Modular Sliding Bearing (Flat type) according to one embodiment of the present invention (Cross Section).

FIGURE 4 – Shows a Modular Sliding Bearing (Curved type) according to one embodiment of the present invention (Cross Section).

FIGURE 5 – Shows some possible configurations for a Modular Sliding Bearing.

FIGURE 6 – Shows a system adopting steel cables able to provide a restoring force after a seismic event (Top view).

BEST MODES FOR CARRYING OUT THE INVENTION Figure 1 shows the preferred embodiment of a Modular Sliding Bearing with four bearing points 1. Each bearing point includes a retaining dish 2 equipped with recesses and threaded cavities for easy placing / removal. The retaining dish is threaded and screwed into the Modular Sliding Bearing. A bottom plate (flat 4 or curved 14) is bolted 5 to the foundation raft 6. A top plate 7 is connected together with the bottom plate with bolts 8 for an easy handling and installing. Prior to pouring the floating floor, the bolts 8 are removed to allow sliding. The top plate 7 is used as part of the formwork for casting in situ the concrete that will constitute the floating floor. The forces generated by the bearing points are transferred to the floating floor through a thick plate 9 connected to the casings containing the low- friction components.

Figure 2 shows, from a perspective view, the embodiment depicted in Figure 1. Each bearing point is equipped with a plastic casing 10 used as formwork to generate a cavity to give access to the slider beaerings for maintenance after the floating floor has been poured.

Figure 3 illustrates a cross section of a Modular Sliding Bearing (flat plate version). In this figure the gap 11 between the cast in situ concrete floating floor 12 and the foundation raft 6 is shown. Outside the area where the sliding bearings 13 are installed, an active formwork 14 is used to reduce thickness under concrete pressure and eliminate friction between the floating floor 12 and the foundation raft 6.

In the preferred embodiment the active formwork is a product known as SEISMAT™. The bolts 8 connecting the bottom plate on which the low-friction components slide, are removed prior to pouring the floating floor to release the horizontal constraint. The threaded retaining dish 2 can be unscrewed allowing it and the low friction component to be removed from its casing 13 through the plastic pipe 10.

The plastic casing 10 penetrates completely through the floating floor to allow this access.

Figure 4 depicts a cross section of the Modular Sliding Bearing whereby the embodiment includes a Friction Pendulum bearing having a curved plate 14. A spherical hinge 15 allows rotation of the low- friction components 13 in order to accommodate the variable angle of contact.

Figure 5 shows some possible configurations for a Modular Sliding Bearing. The bearing capacity of the embodiment increases from A to D together with the number of supports provided. Embodiment E can be used when a linear bearing is required / preferable to support the floating floor (e.g. in presence of a linear load on top of the floor).

Figure 6 shows a top view of a system able to provide a restoring force to repositioning the structure after a seismic event. In this embodiment a cable 16 is connected with two bolts 17 to the foundation raft 6 and with the floating floor with a pulley 18. In a preferred embodiment the cable is a galvanized steel strand. In a preferred embodiment the pulley is a component of the Modular Sliding Bearing and it can be in replaced for maintenance purposes through the floating floor with the same procedure described for the low-friction components. Different settings (than the illustrated setting A) of the Modular Sliding Bearing can be used. The retaining bolts are placed in close proximity to the perimeter 19 of the foundation raft for easy access and maintenance of the fixings and to allow replacement of the steel cables.

In the preferred embodiment the bearing modules may be used to remove, inspect and replace (if necessary) a sliding bearing 13 which is located on a flat plate 4 or a curved plate 14 supported on a face of a foundation raft 6. Each bearing is held securely in place by a retaining dish 2 which is screwed into the bearing mount 1 (essentially the thick plate 9).

Initially a modular bearing as shown in Fig. 1 and Fig. 2 is located on the plate (4 or 14). In the preferred embodiment 3 of the 4 bearing mounts have a bearing fixed in place by passing the bearing 13 through the space inside the casing 10 and through the bearing mount and securing the bearing in the bearing mount by screwing in the retaining dish. The remaining, redundant, bearing mount is empty. In this embodiment it is understood that 3 bearings are sufficient to carry the design load at the site of the modular bearing.

With all 3 bearings in place the bolts 8 are removed. A formwork for the floating slab may be formed around the modular bearing, with the plate 7 forming part of the formwork for an underneath surface of the slab. In this case the plate 7 forms the first load bearing member; it is held in place under the slab (when poured) by bolts 20 as shown in Fig. 3 and Fig. 4. The formwork includes a layer of SEISMAT™ which covers the foundation raft 6 between the bearing modules. SEISMAT™ includes an active material which may support the load of the concrete slab when initially poured, and subsequently transfers the load to the plates 7 of the bearing modules as the concrete cures. The upper surface of the concrete slab over the casing openings in the modular bearing may be covered by a removeable cap.

Inspection and maintenance of the bearing may be carried out by removing the cap above the casing opening to allow access to the redundant bearing mount through the interior of the casing. The retaining dish (if fitted) may be released and a bearing inserted through the interior of the casing and into the space between the floating slab and the foundation raft where it is supported on the bottom plate (4 or 14). The new bearing is secured in place by refitting the retaining dish 2.

It may now be possible to remove one of the remaining (original) bearings by opening the cap over the casing, removing the retaining dish and removing the bearing out through the interior of the casing. The load at the site is now provided by 2 of the original bearings plus the new one.

This process may be repeated until each of the bearings has been removed, inspected and replaced into the bearing module. Of course, the last one inspected does not need to be replaced as there will already be 3 bearings in place.

In some cases it may be possible to carry out the above procedure without having a redundant bearing mount in the bearing module. This may be possible, for example, where the design load requires 4 (say) bearings in the bearing module, but the load could be temporarily handled within the safety margin by 3 bearings while one is being inspected/maintained. In this situation all 4 of the bearing mounts in the bearing module contain a bearing. When inspection is required one of the 4 bearings is removed as outlined above and replaced by another bearing. In this manner the time in which there is only 3 bearings in place may be minimized, thus reducing the risk of failure. Alternatively, following maintenance the removed bearing may be reinserted into the empty bearing mount.

In yet other situations the load carried by the bearing to be removed may be provided by a load bearing member, such as a threaded bolt or a jack. A threaded bolt may be used by providing a mount in the bearing module in the form of an internally threaded cylinder, where the bolt is configured to screw into the cylinder. In the case of a jack the bearing module may include an access for the jack through the interior of the casing so that the jack may be deployed on the bottom plate (4, 14) and operated to take up the load below the concrete slab.

In these embodiments the load bearing member supports the load of one of the bearings while each bearing is inspected and replaced. While this may reduce the efficiency of the sliding bearing while the load bearing member is in place, in practice it is considered unlikely that a seismic event will occur while the bearings are being inspected/maintained.

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof as defined in the appended claims.

Claims (19)

WHAT WE CLAIM IS:

1. A method of use of a modular bearing system for providing a bearing between a first structure and a second structure, wherein the modular bearing system includes a plurality of bearing modules, each bearing module including: a first load bearing member configured to attach to the first structure; a first bearing mount and a second bearing mount each rigidly attached to the first load bearing member, the bearing mounts configured to releasably secure a bearing or a load bearing member, a casing around the first bearing mount and the second bearing mount, the casing configured to provide a space in the first structure through which the first bearing mount and the second bearing mount can be accessed and through which the first bearing can be moved to or from the first bearing mount, the method including the steps of:  forming a bearing site by incorporating the bearing module into the first structure such that the first load bearing member is firmly attached to the first structure and the casing extends through the first structure to an outer surface of the first structure;  locating the first bearing in the bearing module by inserting a first bearing through the space in the casing and through the first bearing mount into the space between the first structure and the second structure so that it is supported on or by the second structure; and  securing the first bearing in the first bearing mount.

2. A method of use of a modular bearing system as claimed in claim 1 including the step of:  repeating steps b to e to add further bearings to the bearing module as needed to provide the required load bearing at the bearing site.

3. A method of use of a modular bearing system as claimed in either one of claims 1 or 2 including the steps of:  passing a second bearing through the casing and the second bearing mount and supporting it on or by the second structure;  securing the second bearing in the second bearing mount; and  releasing the first bearing from the first bearing mount and removing it out through the space in the casing. 4. A method of use of a modular bearing system as claimed in either one of claims 1 or 2 including the steps of:  providing a second bearing mount in the bearing module, the second bearing mount configured to releasably engage with a second load bearing member;  securing the second load bearing member in the second bearing mount and supporting it on or by the second structure;  removing the first bearing by releasing it from the first bearing mount and moving it through the first bearing mount and out through the space in the casing;  replacing the removed bearing using steps b to e of claim 1; and  releasing and removing the second load bearing member from the second bearing mount.

4. A method of use of a modular bearing system as claimed in any one of the preceding claims wherein the first structure includes a floating concrete slab and the second structure includes a foundation raft, wherein the floating concrete slab is poured in situ above the foundation raft.

5. A method of use of a modular bearing system as claimed in claim 4 wherein the bearing module forms part of the formwork for pouring the floating slab.

6. A method of use of a modular bearing system as claimed in any one of the preceding claims wherein the bearing module includes a plurality of bearing mounts.

7. A method of use of a modular bearing system as claimed in claim 6 wherein at least one of the plurality of bearing mounts does not support a bearing.

8. A modular bearing system for providing a bearing between a first structure and a second structure, wherein the modular bearing system includes a plurality of bearing modules, each bearing module including: a first load bearing member configured to attach to the first structure; a first bearing mount rigidly attached to the first load bearing member; a second bearing mount rigidly attached to the first load bearing member; a casing around the first bearing mount and the second bearing mount, wherein the bearing mounts are configured to releasably secure either a bearing or a load bearing member, and the casing is configured to provide a space in the first structure through which the first bearing mount and the second bearing mount can be accessed and through which the first bearing can be moved to or from the first bearing mount.

9. A modular bearing system as claimed in claim 8 including a plurality of bearing mounts.

10. A modular bearing system as claimed in claim 9 wherein, in use, at least one of the plurality of bearing mounts does not support a bearing.

11. A modular bearing system as claimed in any one of claims 8 to 10 wherein the load bearing member includes a plate configured to attach to a surface of the first structure opposite a face of the second structure.

12. A modular bearing system as claimed in any one of claims 8 to 11 wherein the casing extends orthogonally away from the plate, the casing having a height substantially the same as a depth of the first structure.

13. A modular bearing system as claimed in any one of claims 8 to 12 wherein the casing includes a sleeve associated with each bearing mount in the bearing module, each sleeve providing a space allowing access to the enclosed bearing mount and through which a bearing can pass.

14. A modular bearing system as claimed in any one of claims 8 to 13 wherein the bearing includes either a flat sliding bearing or a friction pendulum bearing.

15. A modular bearing system as claimed in any one of claims 8 to 13 wherein the bearing includes a rubber bearing.

16. A modular bearing system as claimed in any one of claims 8 to 15 including a second bearing retainer configured to releasably attach to a second bearing mount and to locate a second bearing at the second bearing mount.

17. A modular bearing system as claimed in any one of claims 8 to 15 including a second bearing mount configured to support a load bearing member capable of supporting a load the same as or greater than that supported by the first bearing.

18. A modular bearing system as claimed in claim 17 wherein the second bearing mount includes a threaded cylindrical aperture and the load bearing member is a threaded bolt configured to engage with the thread of the cylindrical aperture.

19. A modular bearing system as claimed in claim 17 wherein the load bearing member is a jack.