WO1997022762A1

WO1997022762A1 - A construction method and constructions built thereby

Info

Publication number: WO1997022762A1
Application number: PCT/NZ1996/000140
Authority: WO
Inventors: Peter Joseph Lelievre Lewis
Original assignee: Peter Joseph Lelievre Lewis
Priority date: 1995-12-15
Filing date: 1996-12-13
Publication date: 1997-06-26
Also published as: NZ280683A; AU1043197A

Abstract

A construction method for forming a structure from a compressible material, such as straw bales. The compressible material (13) is placed upon a support means (11). A top member (10) extends along the length of the compressible material and is forced towards support means (11) as tensioning lines (12) between top member (10) and support means (11) are tensioned by tensioning devices (16). The lines (12) preferably taper from the base of the support means (11) to the top member (10). This provides stability and isolates the outside faces of the structure from the load, which is transmitted through the central region of the structure. Diagonal bracing lines (30, 31) may also be provided and a variety of possible constructions are disclosed.

Description

A CONSTRUCTION METHOD AND CONSTRUCTIONS BUILT THEREBY
The Technical Field
The present invention relates to a construction method. More
particularly, although not exclusively, the present invention relates to a
method and apparatus for bracing a structure such as a wall or similar
part of a building construction.

Background of the invention
To the present time, examples of alternative building
constructions include free-standing mud brick or compressed, pinned and
plastered constructions whereby the inherent strength of the building
construction (such as a wall) results from the rigidity of the wall material
and/or it's constituents as well as the stability of the wall in general. A
common material used in the latter type of structure is straw in the form
of straw bales.

Building methods using discrete construction elements which are
arranged one upon the other are satisfactory so long as the complete
wall structure remains substantially vertically upright, the wall
components do not disengage or become displaced with respect to one
another thereby causing structural failure in the wall section. Such
constructions may be satisfactory when built on stable foundations which
are unlikely to shift or undergo any short term movement. However, in
countries such as New Zealand where earthquakes are a reasonably
common occurrence or in countries with high wind loads from time to
time such as hurricanes or tornados, the inherent strength of a self
supporting structure such as that described above may be compromised.

Further, alternative building methods may not be easily adapted to traditional construction methods which impart structural integrity to a building structure.

Also, known methods of building free-standing building structures comprising discrete construction elements, can be both time consuming and complicated. Thus there exists a need for a construction method which may be performed quickly, efficiently and cheaply. It is also desirable that such a construction method provide strengthening which will resist structural collapse in the event of an earthquake, high wind or similar occurrence.

Disclosure of the invention
Accordingly it is an object of the present invention to provide a construction technique which at least mitigates the abovementioned problems or provides the public with a useful choice.

According to the invention there is provided a method of bracing an upstanding structure formed of a compressible material supported by support means, the method comprising providing a top member having a width less than the width of the structure along a top surface of the structure and at least partially compressing the compressible material by tensioning a plurality of tensioning lines between the top member and the support means.

Preferably the tensioning lines are in the form of a plurality of loops between the support means and the top member. The tensioning lines are preferably oriented substantially vertically. There may further be provided diagonal bracing lines to enhance structural stability.

The top member is preferably substantially narrower that the width of the structure, preferably less than half the width of the structure, more preferably less than one third the width of the structure.

The top member is preferably substantially narrower in width than the support means. This causes the wires to taper together from the support means to the top member to enhance lateral stability of the structure.

The top member is preferably substantially narrower than the support means, more preferably half or less the width of the support means, more preferably one third or less the width of the support means.

The lines may pass through apertures in the support means or underneath the support means or alternatively through eyes etc fastened thereto. Likewise, the lines may pass through apertures in the top member, over the top of the top member or through eyes etc fastened thereto.

Brief descriDtion of the drawings
The invention will now be described by way of example only and with reference to the drawings in which:
Figure 1 illustrates a cross section through a wall structure.

Figure 2 illustrates a side view of a wall structure;
Figure 3 illustrates a cross section through a wall and roof
construction;
Figure 4 illustrates an intersection between top securing
members;
Figure 5 illustrates a diagonal bracing arrangement.

Figure 6 illustrates a wall structure of a pole house.

Figure 7 illustrates a wall structure mounted upon a conventional
floor on floor joists.

Best mode for carving out the invention
Referring to Figure 1, a cross section through a wall implementing the novel bracing technique of the invention is shown. A concrete foundation 11 is constructed by means known in the art. Straw bales 1 3 are placed upon the foundation 11 and stacked in an offset arrangement.

The bales may normally be stacked 8 high but this will vary depending upon stud height. The dimensions of the straw bales are approximately 1 000mm long x 350mm high x 450mm wide, or as determined by local baling standards. Top member 10 may suitably be formed of wood metal, extruded plastic or from other suitable material.

A top member 10 is placed on top of the uppermost bales aligned substantially parallel with the plane defined by the wall. Top member 10 may suitably be formed of wood, metal, extruded plastic or any other suitable material. Both the top member 10 and the foundation 11 incorporate a plurality of apertures 14 and 1 5 respectively spaced along their lengths through which a tensioning line 12 passes. Apertures 14 and 1 5 may suitably be spaced at 500mm intervals along the top member 10 and foundation 11. The apertures may be formed by embedding a plastic tube or similar (e.g. copper) into the foundation during the construction of the foundation. Alternatively, the tensioning line may be secured to suitable means, such as eyelets secured to the foundation, or may pass underneath the foundation.

Once the top member is located in place, a tensioning member 1 2 is passed through aperture 1 5 and aperture 14, following which the loose ends are drawn together, thereby applying tension between the top member and the foundation, whereupon the tensioning line ends are secured by means of tensioning device 16. Suitable tensioning devices include ezy-lock, Triple-X or Hayes permanent wire strainers. The tensioning wire may be formed of steel or galvanised wire of 2.5 or 3.15 HT or a suitable material such as synthetic string/cord/cables with the appropriate tensile strength approximately 2.5 mm or 3.1 5mum thick.

As can be seen in Figure 1, the width of the top member is less than that of the foundation. Preferably the top member is substantially narrower than the foundation to enhance lateral bracing of the wall.

Preferably the top member is equal to or less than half the width of the foundation. More preferably the top member is equal to or less than a third of the width of the foundation. Accordingly, the tensioning members taper towards the top member and may be embedded in the wall material.

This geometry provides a horizontal tensioning force component which resists the lateral forces applied to the construction during an earthquake or similar event. The horizontal component of the tensioning force also resists movement of the wall structure in extreme wind conditions and generally imparts an enhanced degree of rigidity and structural integrity to the wall construction. This arrangement ensures load is transferred by the top member 10 through the centre of the bales 13 and is isolated from the outer faces of the bales and subsequently applied plasto/stucco cladding.

A side view of the wall construction is shown in Figure 2. In the particular embodiment illustrated, the tensioning lines appear oriented substantially vertically when viewed from the side. Anti-chafing blocks 18 are located proximate the foundation apertures 1 5. These blocks prevent the tensioning wires cutting into the foundation material and detrimentally affecting the structural integrity of the wall and wire. The blocks 18 may be formed of hardwood, soft metal, plastic or similar.

These may be dispensed with if resistance to chafing is otherwise provided.

As can be seen from Figures 1 and 2, by virtue of the tensioning wires passing through apertures 14 and 1 5 whereupon the loops thereformed are tensioned and secured by means of a locking means 16, the forces in the tensioning wires 1 2 are as even as practicable thereby compressing the stacked bales evenly along the wall and along it's length.

Preferably the tensioning means are provided alternately between the inside and outside of the wall along the length of the wall to balance forces in the structure.

The tensioning wires 1 2 are tensioned so as to produce a compressive force in excess of the total load experienced by the wall when, for example, a roof is built thereupon. For example, if the wall is to support a 20 tonne roof and 20 tensioned wires are distributed evenly along its length, each tensioning wire is tensioned to in excess of 1 tonne.

Such a technique "pre-tensions" the supporting walls of the structure so that the vertical dimensions of the supporting walls may be ascertained in advance without the requirement of allowing or compensating for the settling of the wall under the weight of a partially or fully constructed roof section.

A significant advantage of the present bracing technique is that when a conventionally constructed structure such as that shown in figures 1, 2 and 3 is built, it must be left to settle for a significant period of time with a roof or similar structure built thereon before the outer and/ or inner surfaces can be plastered or treated in a similar manner. By means of the present invention, in the form described herein or in a variation thereof, the vertical supporting structures are preloaded and the structure may be built much more rapidly. This can be a significant advantage in geographical areas prone to unpredictable rainfall or similar meteorological conditions.

Further, by using a compressible material, such as straw, the lateral and vertical force imparted to such a structure by an earthquake event may be more easily absorbed thereby reducing the potential for structural damage. Depending on the geographical area in which the structure is being built, the present construction lends itself to a method whereby the roof is constructed first and raised on a scaffold or beams structure. The supporting walls are then built in accordance with the present invention following which the roof is lowered onto the wall construction. This provides additional protection for the wall structures during the building process.

Figure 3 illustrates a building structure incorporating walls 50 and 51 and roof 52. Bales may be cut so as to fit the space between the ceiling members and roof thereby providing insulation and additionally resilient constructional reinforcing.

Figure 4 shows a vertical view of the junction between a wall 40 and adjacent wall 41. In this case the top member 42 extends into the adjacent walls 41 structure where they are joined by mechanical means, such as gang nails, known in the art.

Figure 5 illustrates an alternative arrangement of tensioning wires. Diagonal tensioning wires 31 and 30 may be used in conjunction with vertical tensioning wires 1 2. As in the case of the vertical tensioning wires 12, the diagonal tensioning wires 30, 31 pass through the apertures in the top member and the foundations. In this way a horizontal component of tensioning force is produced as well as a vertical component. It is understood that such a combination enhances the torsional rigidity of the wall structure. As can be seen from Figures 1, 2 and 3 the tensioning wires cut into the compressible material.

The present bracing technique may be adapted to multi-storey constructions wherein a further support member is mounted upon a first storey upper member and the tensioning lines located appropriately.

Figure 6 illustrates a wall of a pole house utilising the technique of the invention. Logs 60 run the length of the wall and rest upon logs 61. 60 and 61 may also be of milled timber on plywood or any combination of the previous.

Morter infill 62 may be provided between logs 60. Straw bales 63 are stacked upon logs 60 and a top log 64 is placed on top of the wall. Tensioning lines 65 pass through apertures in logs 60 and 64 and a tensioning device is used to tension the lines in the normal way.

Referring now to figure 7 there is shown a straw bale wall mounted upon a floor of a conventional structure. Floor joists 78 are mounted upon conventional foundations 79 in the normal way. Wood blocking members 70 are provided between floor joists 78. Conventional flooring 71 is secured to floor joints 78. Packing members 72 are provided along the length of the wall on top of flooring 71. An elevated platform 73 is secured to packing members 72. Straw bales 74 are stacked upon platform 73 in the normal manner. Top log 75 is centrally placed along the top of the straw bales 74. Apertures 80 are drilled at intervals through top log 75 and apertures 81 are drilled through floor 71 at intervals. Wire 76 passes through aperture 80 around the straw bales, under blocking members 70, through aperture 81 with the ends being joined at tensioning means 77.

A plurality of such lines 76 may then be tensioned by tensioning means 77 to tension the structure as previously described.

While the present example has been described as using a high tension galvanised wire, other materials may be suitable such as synthetic extruded substances or polyester strings with appropriate tensioning devices.

Wherein the aforegoing description reference has been made to member or integers having known equivalents, then such equivalents are included as if they were individually set forth.

Although the invention has been described by way of example and with reference to a particular embodiment, it is to be understood that modifications and/or improvements may be made without departing from the scope of the invention as defined in the appended claims.

Industrial ADPlicabilitv
The method of the invention may find application in a wide range of construction applications, particularly the construction of dwellings.

Claims

WHAT WE CLAIM IS:

1. A method of bracing an upstanding structure formed of a compressible material supported by support means, the method comprising providing a top member having a width less than the width of the structure along a top surface of the structure and at least partially compressing the compressible material by tensioning a plurality of tensioning lines between the top member and the support means.

2. A method as claimed in claim 1 wherein the top member is positioned so as to transfer load from the top member through the centre of the structure whilst substantially isolating the faces of the structure from the load.

3. A method as claimed in claim 1 or claim 2 wherein the tensioning lines are in the form of a plurality of loops secured between the support means and the top member.

4. A method as claimed in any one of the preceding claims wherein the width of the top member is less than or equal to half the width of the structure.

5. A method as claimed in any one of the preceding claims wherein the width of the top member is less than or equal to one third the width of the structure.

6. A method as claimed in claim any one of the preceding claims wherein the top member is narrower than the support means.

7. A method as claimed in claim 6 wherein the top member is substantially narrower than the support means.

8. A method as claimed in claim 6 wherein the top member is half the width of the support means or less.

9. A method as claimed in claim 6 wherein the top member is 1/3 the width of the support means or less.

10. A method as claimed in any one of the preceding claims wherein the lines taper together from the support means to the top member to enhance lateral stability.

11. A method as claimed in any one of the preceding claims wherein the tensioning lines pass substantially vertically between the support means and the top member.

1 2. A method as claimed in any one of the preceding claims wherein one or more diagonal bracing line is provided between the support means and the top member.

13. A method as claimed in claim 1 2 wherein the one or more diagonal bracing line is inclined to the vertical at such an angle as to provide effective lateral bracing.

14. A method as claimed in claim 12 or claim 13 wherein diagonal bracing lines are provided at both inclinations to the vertical across the structure.

1 5. A method as claimed in any one of the preceding claims wherein the lines pass through spaced apart apertures in the top member.

16. A method as claimed in claim 15 wherein the support means is a concrete foundation and the lines pass through apertures in the foundation.

17. A method as claimed in claim 16 wherein tubes are placed at spaced apart intervals through the foundation during its formation to provide apertures in the foundation.

1 8. A method as claimed in any one of claims 1 to 1 5 wherein the support means comprises logs.

19. A method as claimed in claim 18 wherein apertures are drilled in the logs to allow the lines to pass therethrough.

20. A method as claimed in any one of claims 1 to 1 5 wherein the lines pass underneath the support means.

21. A method as claimed in claim 20 wherein the foundations are formed of timber.

22. A method as claimed in any one of the preceding claims wherein the lines are tensioned so as to compress the structure by an amount in excess of a load produced by a second structure to be placed thereon.

23. A method as claimed in any one of the preceding claims wherein the lines are embedded in the compressible material to form a substantially straight line between the support means and the top member.

24. A method as claimed in any one of the preceding claims wherein the top member is a wooden beam.

25. A method as claimed in claim 24 wherein spaced apart apertures are provided in the wooden beam.

26. A method as claimed in any one of the preceding claims wherein the lines are tensioned by wire strainers.

27. A method as claimed in claim 26 wherein wire strainers are provided on alternate sides of the structure along the length of the structure.

28. A method as claimed in any one of the preceding claims when the compressible material comprises a plurality of stacked straw bales.

29. A method as claimed in claim 1 substantially as herein described.

30. A method substantially as hereinbefore described with reference to any one of the embodiments shown in the accompanying drawings.

31. A structure formed by the method of any one of the preceding claims.

32. A structure substantially as herein described with reference to any one of the embodiments shown in the accompanying drawings.

33. A structure comprising: a support means; a wall formed of a compressible material; a top member having a width less than the width of the wall lying along the top of the wall; and a plurality of tensioning lines secured between the support means and top member which force the top log towards the support means.

34. A structure as claimed in claim 33 wherein the top log is positioned so as to transfer load from the top member through the centre of the structure while substantially isolating the faces of the wall from the load.

35. A structure as claimed in claim 33 or claim 34 wherein the tensioning lines are in the form of a plurality of loops secured between the support means and the top member.

36. A method as claimed in any one of claims 33 to 35 wherein the width of the top member is less than half, preferably than less than a third the width of the wall.

37. A structure as claimed in any one of claims 33 to 36 wherein the top member is narrower than the support means, preferably substantially narrower, preferably less than half the width of the support means, more preferably less than one third the width of the support means.

38. A structure as claimed in any one of claims 33 to 37 wherein the lines taper together from the support means to the top member to enhance lateral stability.

39. A structure as claimed in any one of claims 33 to 38 wherein the tension lines pass substantially vertically between the support means and the top member.

40. A structure as claimed in any one of claims 33 to 39 wherein one or more diagonal bracing line is provided between the support means and the top member.

41. A structure as claimed in claim 40 wherein the one or more diagonal bracing line is inclined to the vertical at such an angle as to provide effective lateral bracing.

42. A structure as claimed in claim 40 or 41 wherein diagonal bracing lines are provided at both inclinations to the vertical.

43. A structure as claimed in any one of claims 33 to 42 wherein the lines pass through spaced apart apertures in the top member.

44. A structure as claimed in claim 43 wherein the support means is a concrete foundation and the lines pass through apertures in the foundation.

45. A structure as claimed in claim 44 wherein tubes are placed at spaced apart intervals through the foundation.

46. A structure as claimed in any one of claims 33 to 43 wherein the support means comprise logs.

47. A structure as claimed in claim 46 wherein apertures are drilled in the logs to allow lines to pass therethrough.

48. A structure as claimed in any one of claims 33 to 43 wherein the lines pass underneath the support means.

49. A structure as claimed in claim 48 wherein the foundations are formed of timber.

50. A structure as claimed in any one of claims 33 to 49 wherein the lines are tensioned so as to compress the structure by an amount in excess of a load produced by a second structure to be placed thereon.

51. A structure as claimed in any one of claims 33 to 50 wherein the lines are embedded in the compressible material to form a substantially straight line between the support means and the top member.

52. A structure as claimed in any one of claims 33 to 51 wherein the top member is a wooden beam.

53. A structure as claimed in claim 52 wherein spaced apart apertures are provided in the wooden beam.

54. A structure as claimed in any one of claims 33 to 53 including wire strainers to tension the lines.

55. A structure as claimed in claim 54 wherein the wire strainers are provided on alternate sides of the wall along the length of the wall.

56. A structure as claimed in any one of claims 33 to 55 wherein the compressible material comprises a plurality of stacked straw bales.