AU2007203652A1 - Precast concrete building system - Google Patents

Description

Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT

APPLICANT:

Invention Title: PBS PROPERTY GROUP PRECAST CONCRETE BUILDING SYSTEM The following statement is a full description of this invention, including the best method of performing it known to me: PRECAST CONCRETE BUILDING SYSTEM FIELD OF THE INVENTION The invention relates to a method of constructing buildings, such as houses, warehouses and structures of similar dimensions. In particular, the invention relates to a method and associated components of a pre-cast building system.

BACKGROUND OF THE INVENTION Residential housing is generally supported on a poured concrete foundation buried below the finished, or final, ground level. A typical foundation for a residential home is depicted in FIG 1. In a typical procedure, a trench is dug into the ground G and around the perimeter of the building. Concrete is poured into a formwork prepared trench to form the footing 10. The size of the finished concrete footing will depend upon the nature of the sub-soil or soil classification, however is usually at least 450mm deep and 350mm wide around the entire perimeter of the house. The poured concrete is given at least one day to cure before further building work can take place.

With reference to FIG 1, in a standard brick veneer construction, once concrete footing 10 has cured, a bricklayer lays two parallel rows (an inner row 12 and outer row 14) of one or more bricks or blocks on the footing 10 up until just below the finished floor level of the house is reached. A single outer row of bricks 16 is then laid to provide the form work allowing for the cavity board (or screeding point) for the concrete slab 18 which forms the floor of the house.

Standard house bricks are typically 230mm x 110mm x 76 mm in size and take a considerable amount of time and skill to position as they must be horizontal to support the slab 12 and exterior wall structures.

Once the bricks 12, 14 and 16 are laid, the mortar joints are allowed to cure for at least one day. Afterwards, the outer perimeter of the foundation is backfilled.

Loose base material 20, such as sand or gravel, is used to fill the interior of the foundation to provide a base for the floor slab 18. For a typical residential home the process of preparing the foundation can take at least four to five days. In addition, up to seven different labourers or contractors can be involved in digging the foundation trench, laying the bricks and slab, and performing the various clean-up tasks.

Pre-cast foundation systems which attempt to address some or all of the above mentioned problems are known. For example, US Patent No. 6,314,693 teaches the use of pre-cast concrete panels in conjunction with a plurality of pre-cast concrete footing pads. The pre-cast concrete foundations members are placed within a trench, and a bulldozer is used to backfill around each of the components. Sand or gravel is then placed within the perimeter of the foundation and a slab of poured concrete is formed on top of the sand or gravel.

US Patent No. 6,314,693 differs in a number of significant ways from the invention described herein, as will become apparent from the discussion of the invention below.

In view of the discussion above, there is a need in the art for components and methods that streamline or improve the process of constructing a building, or at the very least to provide an alternative to known methods and components.

SUMMARY OF INVENTION The present invention provides a pre-cast concrete panel, associated components, and a pre-cast building construction system. In particular, the invention relates to a pre-cast foundation and wall system for residential housing, or buildings of similar dimensions.

In one aspect the invention resides in a pre-cast concrete panel for use in constructing a building, comprising: a wall segment; a foundation segment; two or more aligning holes; one or more cranks and/or one or more fasteners into which one or more cranks can be fastened.

Preferably, the foundation segment is of sufficient length to spaning two or more footings of the building. Most preferably, the foundation segment is 2-10 metres in length. Preferably, the foundation segment is of sufficient strength to distribute the weight of the building to the footings.

Preferably, the wall segment of the concrete panel further comprises one or more fasteners for attachment of a bracket, whereby the bracket is capable of permanently fixing the panel to a similar consecutive panel to form a contiguous building wall and foundation structure.

Preferably, one or more cranks are connected to one or more ferrules located in the panel. Preferably, the longitudinal axis of the one or more cranks is perpendicular to the panel and capable of being encased in the concrete floor slab of the finished building.

Preferably, the foundation segment has two or more aligning holes which are capable of receiving one end of an aligning member protruding from two or more footings. Preferably, the panel has a recess on one side of the wall segment for placement of a lining material.

Preferably, the panel has at least one point for attachment of a screeding member. Most preferably, the screeding member can be reversibly attached to the panel via the at least one attachment point.

In another aspect, the invention resides in a method of constructing a building, comprising: levelling a building site so that it is approximately horizontal on one or more levels; optionally excavating a trench around the perimeter of the proposed building; excavating two or more holes for footings around the perimeter of the building; constructing two or more footings in the two or more excavated holes; fixing at least one pre-cast concrete panel according to claim 1 to the one or more footings to form the foundation and wall of the building; pouring a concrete floor slab within the perimeter of the concrete panels.

Preferably, an aligning member protruding from the one or more footings is positioned in an aligning aperture in the foundation segment of the panel.

Preferably, the aligning member is a steel bar.

Preferably, at least one or more cranks on the panel are fixed to the building floor slab. Most preferably, the floor slab is also in direct contact with the two or more footings. Preferably, the crank is connected to a fastener in the panel.

To facilitate the understanding of this invention, a number of terms are defined below. Terms defined herein have meanings as commonly understood by a person of ordinary skill in the areas relevant to the present invention. Terms such as "an" and "the" are not intended to refer to only a singular entity, but include the general class of which a specific example may be used for illustration. The terminology herein is used to describe specific embodiments of the invention, but their usage does not limit the invention, except as outlined in the claims.

As used herein the term footing means that part of a building foundation that transfers and distributes the weight of the building directly onto the ground.

Footings preferably rest on undisturbed soil. One example of a footing is a pier footing.

By pre-cast is meant, unless the context requires otherwise, a concrete structural member that has been cast into form before being transported to its site of installation.

As used herein the term "crank" means a steel bar or rod which is connected and protrudes from a concrete panel or fixture for connection to a second concrete panel or fixture. A crank may simply be connected to the concrete panel or fixture by virtue of being partially encased therein, may be tied or otherwise connected to reinforcing in the panel or fixture, or may be connected via a ferrule in the panel or fixture. In relation to the latter, cranks may have a thread or flange for connection to a ferrule encased in a panel or fixture.

Herein, the term "starter bar" is used herein interchangeably with the term "crank".

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that the prior art forms part of the common general knowledge in Australia.

BRIEF DESCRIPTION OF DRAWINGS The invention will now be described in a non-limiting manner with respect to a preferred embodiment in which:- FIG 1 is section through a typical prior art foundation for a residential building.

FIG 2 is a plan view of the wall and foundation system according to the preferred embodiment of the invention.

FIG 3 is a front elevation of a building wall panel according to the preferred embodiment.

FIG 4 is a section through a building wall and foundation according to the preferred embodiment.

FIG 5 is a section through a building wall and foundation, including detail of the flooring slab, according to the preferred embodiment.

FIGS 6(a) to 6(c) are expanded sectional views depicting the connection of one wall panel to a consecutive panel.

FIGS 7(a) and 7(b) is a sectional view of the top and bottom of a panel of the invention.

f FIGS 8(a) and 8(b) are sectional plan and elevation views of a system for joining panels at 90 degrees according to the invention. FIG 8(c) is a perspective view of the joining system.

FIGS 9(a) and 9(b) are sectional views of two methods systems for connecting (a wall panel of the invention to the building roof according to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT The invention of the preferred embodiment relates to a method and associated components of a pre-cast concrete building system. In particular, the preferred embodiment describes a pre-cast wall panel, which in the finished building is integrally linked to foundation members, and the building floor slab.

Whilst the invention is described with reference to residential buildings, the person skilled in the art will appreciate that the invention could just as easily be employed in the building of other structures of similar dimensions, such as small warehouses, or other small to medium general purpose structures.

The invention can be used in conjunction with aspects of the precast concrete footing system described in the applicant's co-pending Australian Application No. which has the same filing date at the present application, the contents of which are incorporated in their entirety herein by cross reference.

According to the preferred embodiment, pre-cast concrete members or panels are manufactured off-site and transported to a housing site where they are jointed to form the walls of the completed house. FIG 2 depicts an example of an arrangement of panels for a house. Concrete panels 22(a) to 22(p) are cast off-site and joined together on-site to form a substantially contiguous wall perimeter for the completed house. Typically, each panel has a length corresponding to the length of a corresponding side of the building perimeter.

Typically, each panel has a similar width and height, except where alternative arrangements are required, such as for a split-level building. The skilled addressee would appreciate that possible panel configurations are virtually unlimited and accordingly a house of any shape and/or size can be constructed employing this method.

Prior to installing the panels on-site, the site is preferably scraped, benched, or tiered, so reasonably flat on one or more levels. Holes are excavated at intervals around the perimeter of the building and subsequently filled with concrete to form footings for the finished building. For example in FIG 2, 24(a) to 24(w) depicts a suitable arrangement of pier footings. The skilled addressee will appreciate that it is highly desirable that footings be supported by firm natural ground, and accordingly the size and shape of the footings will be dictated by local conditions. However, in many instances the footings will be at least 600mm deep and approximately 400 to 600mm square, or a similar cylindrical diameter. Optionally, a trench may also be dug around all, or a part of, the perimeter to essentially connect the footings, as depicted by 26(a) to 26(c) of FIG 2.

According to the invention, footings on any one level are constructed to the same finished level. This can be achieved by any conventional means, but is preferably accomplished by use of laser levelling equipment.

The wall panels according to the invention are preferably laid directly on to the pier footings. As discussed in greater detail below, in the event that minor differences eventuate between the finished levels of the footings, levelling shims can be employed to ensure that the pre-cast panels sit horizontally on the footings. Where footings are constructed in an excavated trench, upon completion of the panel installation, the trench can be filled so that the bottom of the wall panel is essentially covered and does not form part of the building facade. Alternatively, where footings are finished to final ground level, almost the entire panel may form part of the building's fagade.

FIG 3 depicts an example of a panel member 28 according to the preferred embodiment, including window aperture 30. The panel 28 includes at least two lifting shackles. The shackles facilitate lifting of the panel as it is transported from its place of manufacture to the construction site. A crane or similar lifting device connected to the lifting shackles can be used on-site to assist in correctly N positioning the panel. As discussed above, panels are preferably positioned using a laser levelling device, however traditional methods are also suitable.

N Panel 28 includes aligning holes 32 to assist in positioning the panel on the footings 24.

According to the preferred embodiment holes are drilled in the footings and an aligning dowel is glued, or otherwise secured, in the footing. Preferably, the aligning dowel is reinforcing type steel bar of 12 to 30 mm in diameter. Most preferably, the aligning dowel is 20 mm in diameter, for example an N20 bar.

Generally, the aligning dowel will be at least 200 mm in length and extend at least 100 mm into the footing. In construction of a building, the aligning dowel is located in the aligning hole 32 of the panel 28. Preferably, the aligning dowel 36 is fastened, for example using adhesive, in aligning hole 32. Alternative fastening means would however be apparent to the skilled addressee. For example, a ferrule could be incorporated in the panel 28. In addition to securing panels to the footings, panels are also secured to adjacent panels by use of one or more fixing brackets discussed in greater detail below. As discussed above, one or more shims 38 can be employed to ensure that the installed panel is horizontal where there are minor differences between footings.

FIG 3 also depicts ferrules 34, which are used in conjunction with cranks (not shown) to tie the panels to the concrete floor slab of the building under construction. Ferrules are preferably located at approximately 900mm centres along the length of the panel, with an additional ferrule approximately 300mm from either end of the panel. Alternative arrangements would be readily apparent to the skilled addressee.

The panels according to the invention are precast concrete with an approximate thickness of 80 to 300 mm. Preferably, panels are approximately 90 to 200 mm thick. Most preferably, panels are approximately 100 to 150 mm thick. Panels preferably contain reinforcing bars to increase the strength of the panel to that required. Optionally, panels can comprise two or more sections of different thickness. For example, it is often desirable to have wall panels slightly thinner above the final slab level to allow for the installation of lining material, such as plasterboard. Such an arrangement is depicted in FIG 4.

With reference to FIG 4, a panel 28 is fastened to a footing 24. Also depicted is an indentation 42 for a wall lining, levelling shims 38, ferrule 34 and crank In constructing a building according to the invention, once panel 28 is positioned on footing 24, crank 40 is secured to ferrule 34. Crank 40 and ferrule 34 have a male/female relationship which facilitates attachment. For example, cranks can be screwed into the ferrules on panel members.

As discussed in greater detail below, when the floor slab is poured, the crank 34 acts to permanently fix the panel 28 to the floor slab. Preferably, crank or starter bar 40 is tied to the slab reinforcing and encased by the flooring slab concrete. Typically, cranks are steel of 8 to 16 mm in diameter, 250 to 500 mm in length, and spaced at regular intervals along the length of a panel. Most preferably, cranks are reinforcing type steel bars of 12 mm in diameter (for example N12 bars with yield strength of 500 MPa), 350 mm in length, and spaced at regular intervals of 900 mm along the length of the panel with an extra crank 300 mm from each end of the panel. Alternative arrangements for cranks would be readily apparent to the skilled addressee. For example, an alternative crank arrangement is that of protruding loops, or semicircles, of reinforcing rod spaced at intervals along panel 28. The skilled addressee will appreciate that it is highly desirable, although not completely necessary, that the cranks can be attached to and thus become integral with the reinforcing steel in the floor slab.

FIG 5 depicts the panel 28 of the invention after the floor slab 48 has been laid.

As discussed above, the cranks fixed to the panel are now integrated with the slab. Thus, floor slab 48 is fixedly secured to the wall panel 28 whilst partially bearing on the footing 24, affording structural advantages to the final building.

In this regard, not only does the building system of the invention greatly simplify building construction in comparison with the prior art methods, but in addition the floor slab is fixed to wall elements in the final construction which increases the strength and resilience of the completed building.

As discussed above, upon completion of the building structure, soil may be backfilled to covers the bottom section of the panel, if required.

FIGS 6(a) to 6(c) depict a number of alternative arrangements for connecting the upper wall section of panel members. FIG 6(a) depicts a bracket 68 for use where one panel is butted against another panel to form a corner. The bracket 68 is also depicted in FIG 6(c) when viewed from a section through A. FIG 6(b) depicts an alternative system for securing panels at 90 degrees. In FIG 6(b) panels are butted together at 90 degrees and bracket 70 on one of the panels is positioned through and over the adjacent panel. FIG 6(c) also depicts this arrangement when viewed from B.

FIG 7 depicts a preferred panel configuration according to the preferred embodiment, with FIG 7(a) depicting the upper section of the panel, and FIG 7(b) depicting the lower section of the panel. As depicted in FIG 7(b) panel 28 includes a larger (or thicker) foundation section 64 which in the final building spans two or more footings and provides a foundation for the building.

The panel 28 includes internal lining 46 which is positioned on recess 42 and secured by fasteners 62. The fasteners can be 60 to 110 mm in length, preferably 70 to 100 mm and most preferably approximately 90 mm in length.

Preferably, lining 46 is polystyrene or a similar material. Beading 66 facilitates Nattachment of additional lining material. Preferably, beading 66 is timber, ;preferably softwood, or an equivalent material that facilitates easy attachment of additional lining material.

FIGS 8(a) to depict a further arrangement for securing adjacent panels at I right angles. FIG 8(c) is a perspective view of the bracketing arrangement as depicted in FIGS and L-shaped bracket 72 is secured to adjacent panels by fasteners 74. A single bracket is preferably placed towards the upper end of panels to be secured, however if required multiple brackets can be Semployed. Panel 28 includes a recess 76 in the internal lining 46 so that the bracket can be fully covered by a lining board, or the like.

FIGS 9(a) and 9(b) depict two systems for connecting the walls of the building to the roof structure. FIG 9(a) includes panel 28, internal lining 46, final lining 84, truss 80 and fastener 78. In construction of a building, truss 80 is connected to the top of panel 28 by fastener 78. The final lining 84 includes, lining materials commonly known in the art, for example plasterboard.

Alternatively, as depicted in FIG L-shaped bracket 88 is fastened to panel 28 and supports final ceiling lining 84. Truss members are secured to panel 28 in a similar fashion to FIG 9(a).

It will be understood that particular embodiments described herein are shown by way of illustration and not as limitations of the invention. The principal features of this invention can be employed in various embodiments without departing from the scope of the invention. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, numerous equivalents to the specific procedures described herein. Such equivalents are considered to be within the scope of this invention and are covered by the claims.

Claims (17)

1. A pre-cast concrete panel for use in constructing a building, comprising: a wall segment; a foundation segment; two or more aligning holes; one or more cranks and/or one or more fasteners into which one or more cranks can be fastened.

2. The pre-cast concrete panel of claim 1, wherein the foundation segment is of sufficient length to spaning two or more footings of the building.

3. The pre-cast concrete panel of claim 2, wherein the foundation segment is 2-10 metres in length.

4. The pre-cast concrete panel of claim 3, wherein the foundation segment is of sufficient strength to distribute the weight of the building to the footings.

The pre-cast concrete panel of claim 1, wherein the wall segment further comprises one or more fasteners for attachment of a bracket, whereby the bracket is capable of permanently fixing the panel to a similar consecutive panel to form a contiguous building wall and foundation structure.

6. The pre-cast concrete panel of claim 1, wherein one or more cranks are connected to one or more ferrules located in the panel.

7. The pre-cast concrete panel of claim 6, wherein the longitudinal axis of the one or more cranks is perpendicular to the panel and capable of being encased in the concrete floor slab of the finished building.

8. The pre-cast concrete panel of claim 1, wherein the foundation segment has two or more aligning holes which are capable of receiving one end of an aligning member protruding from two or more footings.

9. The pre-cast concrete panel of claim 1, wherein the panel has a recess on one side of the wall segment for placement of a lining material.

10. The pre-cast concrete panel of claim 1, wherein the panel has at least one point for attachment of a screeding member.

11. The pre-cast concrete panel of claim 8, wherein the screeding member can be reversibly attached to the panel via the at least one attachment point.

12. A method of constructing a building, comprising: levelling a building site so that it is approximately horizontal on one or more levels; optionally excavating a trench around the perimeter of the proposed building; excavating two or more holes for footings around the perimeter of the building; constructing two or more footings in the two or more excavated holes; fixing at least one pre-cast concrete panel according to claim 1 to the one or more footings to form the foundation and wall of the building; pouring a concrete floor slab within the perimeter of the concrete panels.

13. The method of claim 12, wherein an aligning member protruding from the one or more footings is positioned in an aligning aperture in the foundation segment of the panel.

14. The method of claim 13, wherein at least one or more cranks on the panel are fixed to the building floor slab.

The method of claim 14, wherein the floor slab is in direct contact with the two or more footings.

16. The method of claim 13, wherein the crank is connected to a fastener in the panel.

17. The method of claim 13, wherein the aligning member is a steel bar.