GB2473017A

GB2473017A - Dome structure

Info

Publication number: GB2473017A
Application number: GB0914938A
Authority: GB
Inventors: Jolyon Eric Emery
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-08-27
Filing date: 2009-08-27
Publication date: 2011-03-02
Anticipated expiration: 2029-08-27
Also published as: WO2011024008A2; GB0914938D0; WO2011024008A3; GB2473017B

Abstract

An assembly for use in the construction of a dome shell structure, and a method of constructing a dome shell structure using the assembly. The assembly comprises an inflatable balloon formed of a flexible sheet material. The balloon comprises a first section 11 of sheet material which defines a domed surface when the balloon is inflated, and a second section 12 of sheet material which defines a base surface. The assembly also comprises a ring support such as a ring beam 410 which supports the balloon in the region where the first section meets the second section as the balloon inflates, to constrain the balloon to form a dome shape. Also disclosed is an assembly characterised by an inflatable form with one or more releasable mouldings mounted to the inflatable form suitable for defining door or window surrounds. A further invention relates to an assembly for constructing a dome shelled structure characterized by an inflatable form with a central support.

Description

DOME STRUCTURE

[001] The present invention relates to an assembly for use in the construction of a dome shell structure, and a method of constructing a dome shell structure.

[002] Techniques for constructing dome shaped buildings by applying layers of material to an inflatable form and allowing the material to set to form a rigid dome shaped shell are known.

[003] For example, Monolithic, Inc. use a technique in which an inflatable sheet is sealed to the edge of a concrete base, and inflated to form a dome shape. Metal rebar is then located over the inflated form, and door and window structures are mounted to the rebar. A layer of concrete is then applied to the surface of the form, encapsulating the rebar, and allowed to set. Once set, the inflatable form is deflated, disengaged from the concrete base, and removed from the structure for reuse.

[004] Such techniques provide a quick, straightforward and cost effective way of constructing strong, long term housing, as compared with conventional building techniques. This is of particular value in developing countries where the demand for housing can not be met by conventional housing solutions, and in disaster zones where existing housing has been destroyed leaving large populations without housing.

[005] Nevertheless, the importance of these factors, coupled with general commercial considerations, drives a demand for further reductions in the time scale, cost and complexity of manufacturing housing, and particularly dome shell structures.

[0061 It is an object of the present invention to address such factors.

[007] According to a first aspect of the present invention there is provided an assembly for use in the construction of a dome shell structure, the assembly comprising:-an inflatable balloon formed of a flexible sheet material, the balloon comprising a first section of said sheet material for defining a domed surface of a dome, and a second section of said sheet material for defining a base surface of a dome; wherein the assembly further comprises a ring support for supporting the balloon in the region where the first section meets the second section as the balloon inflates.

[008] Previously known assemblies used in the construction of dome shell structures use a form which comprises a section of sheet which defines just the domed surface of a dome.

This section is sealed along its edge to a pre-formed rigid foundation which forms the base surface of the dome, to create a sealed volume which can then be inflated.

[009] The rigid foundation requires a substantial quantity of concrete in order to create a strong enough base or concrete ring foundation to resist the forces exerted by the inflated form during the construction process. For example, a dome with a 40m2 base diameter would require a 100-200 mm (4-8 inches) thick base, and thus 10-20 tonnes of concrete.

Moreover, ideally 14-28 days curing time would be required before the base is strong enough to resist the pressures created by the inflated form.

[0010] With the present invention, the form is an inflatable balloon, which comprises sections which define both the domed surface and the base of the dome. This avoids the need to seal the dome to a rigid pre-formed foundation before the form can be inflated.

[00111 To maintain the shape of the dome, a ring support is provided in the region where the domed surface meets the base surface. Importantly, however, the need for a rigid, pre-formed foundation layer can be avoided, which makes construction quicker, easier and cheaper than with previously known methods.

[00121 The ring support may be located within the balloon, to support the balloon from inside.

[0013] In one preferred embodiment, the ring support comprises a ring beam, which may be formed of a plurality of interlocking components. This allows the ring beam to be assembled and disassembled as desired, which is convenient for transport and storage of the ring beam. It also allows the ring beam to be introduced into the balloon, through a relatively small access hole, for assembly inside the balloon. The ring beam is preferably formed of metal, optionally metal tube.

[0014] In another preferred embodiment, the ring support comprises an inflatable tube. The inflatable tube is preferably incorporated within the inflatable balloon in the region where the first section meets the second section. The inflatable tube may be inflated to higher inflation pressure than the inflatable balloon to form a ring shaped support which constrains the shape of the inflatable balloon as it inflates.

[0015] Although there are significant advantages in terms of material costs and construction time scales, associated with not using a concrete base s]ab, there are circumstances in which the use of a pre-formed foundation, for example in the form of a concrete slab or ring may be desirable. In such cases, the ring support of the present invention may comprise a plurality anchors for location in the ground (for example, in a pre-formed foundation) along the outline of a ring, for attachment to the inflatable balloon to support the balloon in the region where the first section meets the second section.

[0016] With previously known methods, it is necessary to form a substantially continuous seal between the base edge of the inflatable form and the concrete base slab. This can be time consuming and complex. Moreover, this is typically achieved using a plurality of straight edged sections which are laid down end to end over the edge of the form, to define a polygonal edge. As a result, when inflated, the base of the form defines a polygon, rather than a continuous curved ring.

[0017] With the present invention, because the inflatable balloon includes a base section, the need for a continuous seal between the balloon and the ground is avoided, and the ring support simply needs to be anchored to the ground at a plurality of points to form a ring support. This is quicker and easier than previously known techniques. Moreover, when inflated, the base of the balloon will naturally define a continuous curved ring at its periphery, which improves the aesthetic appeal and structural integrity of the finished structure.

[0018] The balloon is preferably attachable to the anchors by means of connectors, which are preferably located on the first section of the balloon, conveniently on the external surface thereof. The assembly preferably further comprises a shield member(s) for overlying the anchors and/or connectors, to prevent these being encased in settable material, when applied to the surface of the balloon. The shield member(s) may comprise one or more additional sections of sheet material, for example a skirt section, which may be attached to the balloon, to extend over the connectors and the anchors.

[0019] The ring support is preferably, but not necessarily, circular.

[0020] In a preferred embodiment, the assembly further comprises a central support (centre pole) for attachment to the second section of the balloon, such that the central support extends along a substantially vertical axis of the balloon. In this case, the assembly may further comprise coupling means for coupling the central support to the ring support, to fix the vertical position of the ring support in relation to the central support.

[0021] Whilst the ring support may be sufficient to constrain the balloon to the form of a dome, for large domes or high inflation pressures, the second or base section of the dome will tend to bulge out in the absence of additional internal structure. This may not be of concern in the case where the form is raised above the ground on stilts or piles to create a structure whose floor is above ground level, as may be required if building on a flood plain, for example.

However, where it is desired to build at ground level, the tendency of the base of the balloon to bulge out, causes the base of the balloon to rise up at its periphery, together with the ring support, such that only a central region of the base surface remains in contact with the ground, making the assembly unstable, such that construction of the dome shell structure would be impractical.

[0022] By attaching a central support to the base surface, and then fixing the vertical position of the ring support in relation to this support, the ring support can be maintained at the same vertical position as the centre of the base surface, such that substantially the whole base surface rests on the ground, which improves the stability of the assembly.

[0023] The coupling means for coupling the central support to the ring support preferably comprises a slidable connector, slidably engagable with the central support, for adjusting the vertical position of the ring support.

[0024] This allows the vertical position of the ring support to be adjusted during assembly.

[0025] The coupling means preferably comprises one or more elongate members which, when assembled, extend radially between the ring support and the central support. These elongate or spoke members may be fixed directly to the central support or, more preferably, to the slidable connector (if present) [0026] When assembled, the elongate spoke members preferably extend radially and downwardly from the central support to the ring support. Additiona' support may be provided in the form of elongate support members, which, when assembled, extend diagonally from the spoke members to meet the central support at a lower position to that at which the spoke members meet the central support. Further support may be provided in the form of elongate side support members which, when assembled, extend diagonally from the spoke members to the ring support.

[0027] Whilst the above described structure may be sufficient to maintain a substantially flat base surface of the balloon as it is inflated, for large domes or high inflation pressures, additional structure may be required.

[00281 Thus, in a preferred embodiment of the present invention, the assembly further comprises suspension means for suspending the second section of the balloon from the central support.

[00291 By suspending the second or base section of the balloon from the central support, this section of the balloon can be prevented from bulging outwards, to allow the ring support to lie at ground level.

[00301 The suspension means preferably comprises:-one or more supports for attachment to the central support such that they are located vertically above the second section of the balloon; and a plurality of suspension members each configured for attachment to a respective attachment point on the second section of the balloon, and to a respective attachment point on one of said one or more supports, to extend substantially vertically therebetween.

[0031] Thus, the second section of the balloon is suspended at a plurality of points which are preferably evenly distributed over its surface. This prevents any part of the base surface bulging out to a significant extent.

[0032] The supports of the suspension means preferably comprise a plurality of elongate members, each configured for attachment to the ring support and to the central support.

Preferably, the elongate members are configured for attachment to the central support at a position above the ring support. Accordingly, the supports of the suspension means extend diagonally between the ring support and the central support, diagonally above the second or base section of the balloon.

[0033] The suspension members are preferably elongate members. The supports and/or the suspension members are preferably flexible elongate members. For examp'e, cables, cords, wires or chains.

[0034] The supports and/or the suspension members may each comprise a tensioning device, such as a turn buckle, for adjusting the tension therein.

[0035] The supports may be attached to the central pole by means of the same slidable element as the spoke members (if present) [0036] The suspension means described above is preferably used in combination with the above described coupling means for coupling the central support to the ring support, but may also be used independently of the coupling means.

[0037] In an alternative embodiment of the present invention, the assembly may comprise a plurality of elongate beams, each configured for attachment to two points on the ring support. For example, a (first) array of parallel beams or cross members which, when assembled, extend over the second or base section of the balloon. Optionally, a second array of parallel beams or cross members may be provided, which, when assembled, may extend at an angle to the beams of the first array, preferably an angle of substantially 90°.

[0038] The second surface of the balloon can then be attached to these beams at regular intervals over its surface, by means of clips or ties, for example. This prevents the second surface bulging outwards as the balloon is inflated, such that it lies substantially flat against the ground.

[0039] In another embodiment, the assembly may comprise a plurality of inflatable tube sections which, when inflated, extend across the second or base surface of the balloon.

Preferably, the inflatable tube sections define a (first) array of substantially parallel sections, each of which may extend from one location on the ring support to another location thereon. The inf'atable tube sections may also define a second array of substantially parallel sections each of which may extend from one location on the ring support to another location thereon. The sections of the second array may be oriented at an angle with respect to the sections of the first array, preferably an angle of substantially 90°, to the first array, to form a grid. The tube sections of the first array are preferably interconnected with the tube sections of the second array.

[0040] The tube sections are preferably incorporated within the second or base section of the balloon. In use, the inflatable tube sections may be inflated to a higher pressure than the balloon, to form support members which cofistrain the second or base section of the balloon to a substantially flat surface.

[0041] According to a second aspect of the present invention there is provided a method of constructing a dome shell structure, the method comprising:-providing an inflatable balloon formed of a flexible sheet material, the balloon comprising a first section of said sheet material for defining a domed surface of a dome, and a second section of said sheet material for defining a base surface of a dome; providing a ring support to support the balloon in -10 -the region where the first section meets the second section; and inflating the balloon to a predetermined pressure.

[0042] The method preferably comprises locating the ring support within the balloon.

[0043] The method preferably comprises assembling the ring support from a plurality of interlocking components.

[0044] Alternatively, the method may comprise inflating an inflatable tube to form said ring support.

[0045] Alternatively, or in addition, the method may comprise locating a plurality of anchors in the ground along the outline of a ring, and attaching connectors on the inflatable balloon to said anchors. In this case, the method preferably comprises the step of forming a foundation for the dome shell structure in the ground, and locating the plurality of anchors in the foundation.

[0046] The method preferably further comprises shielding the connectors from settable material during the application thereof to the surface of the balloon.

[0047] The method preferably further comprises attaching a central support to the second section of the balloon, such that the central support extends along a substantially vertical axis of the balloon.

[0048] The method preferably further comprises coupling the central support to the ring support, to fix the vertical position of the ring support in relation to the central support.

-11 - [00491 In this case, the method preferably further comprises adjusting the coupling of the central support to the ring support, to adjust the vertical position of the ring support in relation to the central support.

[00501 The method preferably comprises suspending the second section of the balloon from one or more supports attached to the central support, and located vertically above the second section of the balloon.

[0051] In an embodiment, the method may comprise attaching each of a plurality of elongate beams at two points on the ring support to extend over the second section of the balloon.

[0052] In another embodiment, the method may comprise inflating a plurality of inflatable tube sections to extend across the second section of the balloon.

[0053] According to a third aspect of the present invention, there is provided an assembly for use in the construction of a dome shell structure, the assembly comprising:-an inflatable form for defining a domed surface; and one or more mouldings for defining door and/or window surrounds on said domed surface; wherein the or each moulding is releasably mountable to the inflatable form.

[0054] By mounting the moulding(s) directly to the inflatable form, the door and window surrounds can be located with a high degree of precision in relation to the domed surface. Nevertheless, by disengaging the mouldings from the inflatable form, the inflatable form can be deflated and/or removed independently of the mouldings once the dome shell structure is complete.

-12 - [00551 This allows the mouldings to be retained as support for the door/window surrounds or, more preferably, to be removed from the completed dome shell structure independently of the inflatable form, to avoid causing damage to the structure.

[0056] In this aspect of the invention, the inflatable form preferably, but not necessarily comprises a base section, to form a balloon.

[0057] The or each moulding preferably comprises a surround section which, when mounted to the inflatable form, projects from the domed surface thereof to at least partially surround a door or window opening.

[0058] The or each moulding preferably comprises a masking section for masking the door or window opening. This facilitates the formation of a clean edge to define the door/window opening in the finished dome shell structure.

[0059] The masking section and the surround section are preferably separable. This facilitates accurate placement of the moulding on the inflatable form, and also tacilitates removal of the moulding once the dome shell structure is complete.

[0060] In a preferred embodiment, the or each moulding is releasably mountable to the inflatable form by one or more releasable connectors.

[0061] The or each releasable connector preferably comprises a locator mounted at a predetermined position on the inflatable form, and an elongate member, releasably locatable in said locator to extend outwards from the domed surface -13 -defined by the inflatable form.

[00621 The or each moulding is preferably formed with one or more openings, the or each opening being configured to engage a respective one of the one or more elongate members.

[0063] The or each elongate member preferably comprises a securing device for securing the moulding to the elongate member at a predetermined distance from the domed surface.

[0064] The locators may comprise cup portions for receiving a proximal end of a respective elongate member. The elongate member may be releasably retained in the cup portion by means of a pin configured for insertion through correspondingly formed holes in said cup portion and the proximal end of the elongate member. Alternatively, the elongate member(s) may comprise a screw thread for engagement with a correspondingly formed thread on the respective locator. For example, a thread formed on the internal surface of the cup portion.

[0065] The distal end of the or each elongate member may be formed with a screw thread for engaging one or more nuts, which serve as said securing device.

[0066] One or more of the elongate members (or the elongate member) may be angled along its length such that the distal end thereof extends from the domed surface in a substantially horizontal plane. This makes it easier to orientate the moulding such that the door/window opening lies in a substantially vertical plane.

[0067] Preferably, the or each opening for engaging the elongate member(s) is provided on the masking section of the moulding. Accordingly, the opening(s) and the exposed part of the connector(s) are located in an area corresponding to -14 -a window/door opening of the finished structure and thus are not covered by the layer of concrete when this is applied to form the dome shell. Accordingly, the connectors can be disengaged once the structure is complete.

[00681 Preferably, one or more access openings are provided in the masking section. This allows the mouldings to be disengaged from the inflatable form by disengaging the elongate members from the locators mounted on the inflatable form. Accordingly, the elongate members are left attached to the moulding, and can be easily removed once the inflatable form has been deflated. This avoids leaving the elongate members attached to the inflatable form when it is removed from the inflatable form, where they could do damage to the form, or injure a construction worker.

[00691 According to a fourth aspect of the present invention, there is provided a method of forming one or more doors and/or windows in a dome shell structure, the method comprising:-inflating an inflatable form to provide a domed surface; releasably mounting one or more mouldings to said domed sirface, wherein the or each moulding comprises a surround section which projects from the domed surface of the inflatable form to at least partially surround a door or window opening; applying one or more layers of setting material to the domed surface and a surface of the surround section of the or each moulding; allowing the setting material to set to form a rigid shell; disconnecting the or each moulding from the

inflatable form; and

removing the inflatable form.

-15 - [00701 The method preferably further comprises removing the moulding from the rigid shell once the setting material has set.

[00711 The step of releasabiLy mounting the or each moulding to the inflatable form preferably comprises locating an elongate member in a locator mounted at a predetermined position on the inflatable form, to extend outwards from the domed surface defined by the inflatable form.

[0072] The method preferably further comprises siLotting one or more openings formed at corresponding locations on the or each moulding onto the or each elongate member.

[0073] The method preferably further comprises securing the moulding to the or each elongate member at a predetermined distance from the domed surface.

[0074] The step of disconnecting the or each moulding from the inflatable form preferably comprises disengaging the elongate members from the locators.

[0075] According to a fifth aspect of the present invention, there is provided an assembly for use in the construction of a dome shell structure, the assembly comprising:-an inflatable form for defining a domed surface; and a central support which, when assembled, extends along a substantially vertical axis of the form, through an opening in the domed surface of the inflated form.

[0076] The central support (for example, a pole) may act as a support for various structures within the inflatable form, as described above. Alternatively or in addition, the central support may act as a support for additional devices externally of the inflatable form.

-16 - [00771 For example, the assembly may comprise a canopy for location on said central support. This provides a shelter over the inflatable form during construction of the dome shell structure.

[0078] Further, the assembly may comprise a support structure for supporting a construction worker during construction of the dome shell structure, wherein the support structure is preferably rotatably mountable to said central support. This allows the support structure to be rotated around the inflatable form, allowing the worker convenient access to the surface of the form. The support structure may comprise a ladder for allowing access to the sides of the form, and/or a platform for allowing access to the top of the form.

[0079] According to a sixth aspect of the present invention, there is provided a method constructing a dome shell structure, the method comprising:-inflating an inflatable form to provide a domed surface; and assembling a central support to extend along a substantially vertical axis of the form, through an opening in the domed surface of the inflated form.

[0080] The method preferably further comprises locating a canopy on said central support, to form a shelter over the inflatable form during construction of the dome shell structure.

[0081] The method preferably further comprises rotatably mounting to said central support, a support structure for supporting a construction worker during construction of the dome shell structure.

-17 - [0082] Embodiments of the present invention will now be described in which:- [0083] Figure 1 is a partially cut-away view of an assembly used in the construction of a dome shell structure; Figure 2 is a non-cut-away view of the assembly of figure 1, with the tent canopy omitted for clarity; Figure 3 is a more detailed view of a region on the surface of the inflatable form, which corresponds to a door region of the completed structure; Figure 4 is a perspective view of the internal structure of the inflatable form; Figure 5 shows a section of the central polLe, and the upper and lower sleeve members mounted thereon; Figure 6 is a side view of the spoke and support members of the internal structure shown in figure 4; Figure 7a is a side view of the suspension cables of the internal structure shown in figure 4; Figure 7b is a top view showing a single main suspension cable, in accordance with an alternative embodiment of the invention; Figure 8 is a top view of the spoke and support members of the internal structure shown in figure 4; Figure 9a shows a window moulding; Figure 9b is a cross-sectional view of the window moulding of figure 9a, mounted on the side of the inflatable form; Figures lOa and lOb show a releasable connector for connecting the window moulding of figures 9a and 9b to the surface of the inflatable form; Figure 11 shows a rotatable support structure for use with the present invention; Figure 12 is a partly cut-away view of an assembly used in the construction of a dome shell structure, in -18 -accordance with an alternative embodiment of the invention; Figure 13 is a partly cut-away view of an assembly used in the construction of a dome shell structure, in accordance with another embodiment of the invention; Figure 14 is a partly cut-away view of an assembly used in the construction of a dome shell structure, in accordance with an another embodiment of the invention; Figure 15 shows an assembly used in the construction of a dome shell structure, in accordance with a further alternative embodiment of the invention, in which a skirt section of the inflatable form is omitted; and Figure 16 shows the assembly shown in figure 15, with the skirt section in place.

[0084] Elements common to different figures and different embodiments are identified with the same reference numerals.

[0085] Figure 1 is a partly cut-away view of an assembly used in the construction of a dome shell structure, in accordance with an embodiment of the present invention.

Figure 2 shows a non-cut-away view of the same assembly, with the canopy of the tent structure omitted for clarity. In both figures, the assembly is shown in its assembled form, before the application of a concrete layer.

[0086] The assembly comprises an inflatable form 10 which, when inflated and supported by internal structure 400, adopts a dome configuration.

[0087] The inflatable form 10 is formed of a waterproof and substantially airtight flexible sheet material. For example, polyvinyl chloride (PVC), reinforced mehler, silicon coated braided nylon, tn-laminate, or hepalon. Sections of the sheet material are joined together by substantially airtight seams to form a balloon. In this respect, a plurality of -19 -sections are joined to form the top section 11 of the balloon, which defines its domed surface when inflated. The free edge of the top section is joined to the circumferential edge of a circular section 12, which forms the circular base surface of the balloon.

[00881 Figure 3 is a more detailed view of a region 30 of the inflatable form 1, which corresponds to the main doorway of the finished structure.

[0089] An inflation opening 31 is provided in the inflatable form 10, at a first location in the region 30. The inflation opening is surrounded by a coupling 32 for forming a sealed engagement with an inflation hose (not shown) connected to an external pump. This allows air to pumped into the balloon.

[0090] In other embodiments of the invention, the inflation opening may be provided in the base section 12 of the inflatable form 10, connected to an external pump via a tube buried n the ground.

[0091] A pressure release valve 33 is provided at a second location in the same region 30 of the inflatable form 10.

This allows air to be released from the balloon.

[0092] A manometer 34 is mounted to the outside of the inflatable form 10 in the same region 30, and coupled to the interior of the balloon. This allows the pressure inside the balloon to be monitored, so that a desired pressure within the balloon can be achieved and maintained through controlled operation of the pump and the pressure release valve.

[0093] A sealable access opening 35 is also provided in the region 30. The access opening is formed by a vertical slit -20 - 36 in the form, about 1.5 m (60 inches) in length. The form is joined by an airtight seam around the edge of the slit to one end of a tube of sheet material 37, approximately 50cm (20 inches) in length. This allows a construction worker to access the interior of the form, by stepping through the tube and the slit.

[0094] The free end of the tube is sealable by means of a zip 38. The zip may be a marine zip, or an industrial grade zip. In alternative embodiments, velcro may be used. This allows the access opening to be releasably sealed to prevent air escaping through this opening. When the access opening is not Ln use, the opening of the tube is sealed by means of the zip, and the tube is rolled up and laced to the surface of the form up by means of a cord (not shown) . This reduces any leakage of air through the zip/velcro and avoids distortion of the dome.

[0095] It will be appreciated that, in the absence of additional structural elements to maintain a flat circular base, the balloon described above would inflate into a substantially spherical, ball-like form above a given pressure.

[0096] Accordingly, with the present invention, internal structural elements are provided to constrain the shape of the balloon as it inflates, to achieve the required dome shape.

[0097] The internal structural elements 400 of the present embodiments are indicated in figure 1, and are shown in more detail Ln figures 4-8.

[0098] A circular ring beam 410 of approximately the same diameter as the circular base section 12 of the inflatable -21 -form 10 is located inside the form, and attached to the internal surface of the form in the region where the domed top section 11 meets the circular base section 12. The ring beam comprises a plurality of arc shaped metal tube sections.

In the present embodiment, eight individual sections are used. However, any suitable number of individual sections may be used, depending on the specific application. One end of each tube section is inserted into the other end of another tube section to collectively form the ring 410.

Because the ring beam is formed from a plurality of arc shaped sections, the ring beam can be introduced into the form section by section, and assembled inside the form.

[00991 Each tube section is secured to the tube section in which it is inserted by means of a pin (not shown) inserted through correspondingly formed holes in both tube sections.

One end of each tube section is provided with a plurality of holes spaced along the circumferential direction of the ring beam. This allows the extent to which the tube sections overlap, and thus the diameter of the ring beam 410, to be adjusted.

[00100] By maintaining a fixed diameter at the base of the inflatable form 10, the ring beam 410 ensures that the top section 11 forms the required dome shape, and reduces the tendency of the circular base section 12 to bulge outwards as the form is inflated. In some circumstances, this is sufficient to maintain a substantially flat circular base.

However, for large domes, and increased inflation pressures, the circular base section will tend to bulge out as the pressure inside the form increases.

[00101] This may not be of concern in the case where the inflatable form 10 is supported above the ground on stilts, to create a structure whose floor is above ground level, as -22 -may be required if building on a flood plain, for example.

However, where it is desired to build at ground level, the tendency of the base to bulge out causes the base of the dome to rise up at its periphery, together with the ring beam, making the structure unstable.

[001021 In the present embodiment, additional structural elements are provided to keep the ring beam 410 at ground level, and the base section 12 substantially flat.

[00103] To this end, a centre plate (not shown) provided with a cup is located under the circular base section 12 of the inflatable form 10. The cup is inserted through an opening formed in the centre of the base section, and projects into the interior of the form. The edge of the form defining the opening is attached to the sides of the cup by means of ties, to form a substantially airtight seal.

[00104] A first end of a first pole section, approximately lm (40 inches) in length is screwed into the cup and extends vertically upwards within the inflatable form 1. A first end of a second pole section screws onto the second end of the first pole section, and extends vertically upwards, through an opening formed in the centre at the top of the form, to terminate approximately 50cm (20 inches) above the top of the form. The edge of the form defining the opening is attached to the sides of the second pole section by means of ties, to form a substantially airtight seal. A first end of a third pole section is screwed into the second end of the second pole section, and extends vertically upwards to terminate approximately 3m (120 inches) above the top of the form. The first, second and third pole sections extend along a common vertical axis and form the central support (centre pole) 15 of the assembly. The centre pole is maintained in a vertical orientation by means of guy -23 -ropes (not shown) [00105] As shown in more detail in figure 5, two sleeve members 510, 520 are mounted on the centre pole 15. The inner diameter of the sleeve members is fractionally larger than the outer diameter of the centre pole, such that the sleeve members can slide along the axis of the pole, but cannot move in the radial direction. When assembled for use, the lower of the two sleeve members 510 is located at a pre-determined position above ground level, and is held in this position by means of a pin 514. The precise iLocation is determined in accordance with the size and configuration of the inflatable form 10.

[00106] The upper sleeve member 520 is located vertically above the lower sleeve member 510. Again, the precise location is determined in accordance with the size and configuration of the inflatable form 10. A plurality of pin receiving holes 530 are formed in the centre pole in this region, and a correspondingly formed hole 532 is provided in the sleeve member, such that the upper sleeve member can be secured in a plurality of positions along the axis of the central pole, by means of a pin 534.

[00107] Eight spoke members 420 are attached at one end to attachment points 522 located at regular intervals around the circumference of the upper sleeve member 520.

[00108] The spoke members 420 each comprise a first elongate element, which is attached to the ring beam, and a second elongate element, which is attached to the upper sleeve member 520. The two elongate elements are of substantially equal length and are connected end to end.

[00109] The spoke members 420 extend radially outwards -24 -and downwards to be attached at opposite ends to attachment points 412 located at regular intervals around the ring beam 410.

[00110] Eight support members 430 are each attached via a hinged coupling to a respective one of the spoke members, to attachment points 422 located half way along the respective spoke members 420. In particular, each support member is attached to the first elongate element of a respective spoke member in a region where it is connected to the second elongate element thereof.

[00111] The support members 430 are each are attached at their other end to attachment points 512 located at regular intervals around the circumference of the lower sleeve member 510.

[00112] Accordingly, the support members 430 extend radially outwards and upwards from the centre pole 15 to the spoke members 420.

[00113] In the present embodiment, the attachment points 522, 512 on the upper and lower sleeve members 520, 510 each comprise a planar sided projection, which engages with a corresponding planar sided slot formed in the end of the respective spoke/support member. The slots and projections are formed such that their planar surfaces extend in a substantially vertical plane, when assembled. Pin receiving through holes 523/513 are formed on the projection and in corresponding locations in the spoke/support member 420/430, either side of the slot. A pin (not shown) is inserted through these holes to secure the spoke member to the sleeve member. This forms a hinged connection, such that the angle of the spoke/support members with respect to the upper/lower sleeve member can vary.

-25 - [00114] The attachment points 412 on the ring beam 410 each comprise an opening or eyelet formed on the ring beam.

The opposite end of each spoke member 420 is provided with a hook for engaging one of these openings, to form a hinged connection with the ring beam, such that the angle of the spoke members with respect to the ring beam can vary.

[00115] Although specific types of hinged connection have been described above, it will be appreciated that alternative hinged connections may be used.

[00116] A pair of side support members 470 (shown in figures 6 and 8) are attached via a hinged coupling to the first elongate element of each spoke member 420 n a region where the first elongate element is connected to the second elongate element thereof. The opposite end of each side support member is attached to attachment points 416 located at equal intervals around the ring beam 410, to extend diagonally form the spoke members to the ring beam. The side support members prevent the structure twisting as the inflatable form 1 is inflated.

[00117] With the above described arrangement, the upper sleeve member 520 can be fixed at a relatively high position on the central pole 15, to facilitate the assembly of the spoke and support members 420, 430, 470. Once these members are assembled, the upper sleeve member can be released and pulled down the pole by means of a ratchet strap (not shown), to force the ring beam 410 downwards along the vertical axis of the central pole, to lie, on the ground, at the same level as the centre of the base section 12. The upper sleeve member is then secured in position by means of the pin 534.

-26 - [00118] In some circumstances, this is sufficient to maintain a substantially flat circular base, with the ring beam 410 at ground level. However for large domes or high inflation pressures, the circular base section 12 of the inflatable form 10 will still tend to bulge out between its centre and its circumference, which causes the whole structure to rise upwards above ground level.

[00119] In the present embodiment, this is prevented by means of a plurality of suspension cables, which connect the base section of the form to the centre pole 15. The suspension cables are shown in detail in figure 7.

[00120] In this respect, eight main cables 440 are attached at one end to attachment points 414 located at equal intervals around the ring beam 410, and at the other end to attachment points 524 located at equal intervals around the upper sleeve member 520.

[00121] The attachment points 414 on the ring beam 410 comprise openings or eyelets formed on the ring beam, located halfway between the adjacent spoke attachment points 412.

The attachment points 524 on the upper sleeve member 520 each comprise a series of eyelets located axially above the spoke attachment points 522 on the upper sleeve member 520, and halfway between adjacent spoke attachment points in the circumferential direction. In the present embodiment, a series of three eyelets is provided. However, any convenient number may be provided, including a single eyelet for each main cable 440. The ends of the main cables are attached by means of a clip to the respective eyelets, and the cables are tensioned by means of cable tensioners (not shown) incorporated into the cables.

[00122] In the direction from the ring beam 410 to the -27 -centre pole 15, each main cable 440 comprises a plurality of vertical cables 450, of successively increasing length, attached to the main cable at attachment points 442 located at intervals along its length. In the present embodiment, five vertical cables are provided. However, the precise number depends on the size and configuration of the inflatable form 10. In general, forms with larger base diameters will require higher numbers of vertical cables.

[00123] Each vertical cable 450 is attached at its lower end to attachment points 452 on the base section 12, vertically below the point 442 at which it is attached to the main cable.

[00124] A pair of diagonal cables 460 are attached to each vertical cable 450 at a point on or below the point 442 at which the vertical cable is attached to the main cable 440. The diagonal cables extend diagonally from the vertical cable to attachment points 462 on the base section 12 either side of the vertical cable, and equal radial distances from the centre pole 15.

[00125] In the embodiment shown in the drawings, the vertical cables 450 (and thus the diagonal cables 460) are provided at equal intervals along the main cable. In practice, it may be desirable to vary the distance between the vertical cables, such that those located further from the centre are located closer together. This allows for a substantially even distribution of attachment points over the base section 12, so that it can be suspended evenly over the whole surface.

[00126] Figure 7b shows a top view of a cable assembly for use in accordance with an alternative embodiment of the present invention. In this embodiment, each of the main -28 -cables 44O branches into two cables at a point located substantially half way between the centre pole 15 and the ring beam 410. Vertical cables and diagonal cables (not shown) are suspended at intervals from these main cables, as described above. This arrangement is convenient for larger domes, is it allows the density of attachment po�nts in the outer regions of the base section 12 to be increased, without increasing the density of cables in the central region of the dome, and specifically without increasing the number of attachment points required on the upper sleeve member 520.

For still larger domes, each branch of the main cable may branch again into another two cables, and so forth, to increase the number of attachment points as desired.

[001271 Anchor rods (not shown) are embedded in the ground prior to inflation of the form, to act as anchor points or the finished structure. These anchor rods are designed to extend into the ground by a sufficient distance to permanently anchor the finished structure to the ground.

In practice, the required distance will depend on the nature of the ground and the design of the dome. The anchor points are located at equal intervals along the circumference of a circle substantially equal in diameter to the ring beam 410 and the circular base 12 of the inflatable form 10. The inflated form is located inside the circle defined by the anchor rods, such that exposed ends of the rods are in contact with the external surface of the inflatable form 10, and thus become embedded in the concrete applied to the surface of the form, to anchor the structure to the ground.

[001281 Door and window mouldings 19 are provided at intervals around the inflatable form, to create surrounds for door and window frames in the finished dome shell structure.

-29 - [00129] One of the window mouldings 19 is shown in more detail in figures 9a and 9b. The moulding comprises a masking plate 910 and a surround 920. The masking plate 910 is used to mask out an arch shaped window opening. To this end, the plate 910 has a generally rectangular form, with a curved top edge 912. In practice, the masking plate may be configured to mask out a window opening of any desired shape.

[00130] The masking plate 910 is attached to the surface of the inflatable form 10, to extend in a vertical plane, with its lower edge 914 in contact with the surface of the form, in a central region thereof.

[00131] The surround 920 is shaped to bridge the gap formed between the surface of the inflatable form 10 and the side and top edges of the masking plate 910, and to form a bridge surface between the form and the edge of the masking plate.

[00132] In particular, the surround 920 is configured to slope inwardly from an edge 921 which contacts the inflatable form 10 and an edge 922 which contacts the masking plate 910. Accordingly, the angle at which the surround meets the form is relatively shallow, as compared with the case where the surround extends at right angles from the masking plate.

This provides a graduated transition between the form and the window mouldings, which improves the strength and aesthetic appearance of the finished structure.

[00133] The masking plate 910 is attached to the inflatable form 10 by means of a plurality of connectors 930 provided on the surface of the form, at locations corresponding to the four corners and the top of the window opening. In the present embodiment, five connectors are used to mount the window moulding to the form. However, any -30 -suitable number of connectors may be used.

[00134] The connectors 930 are shown in more detail in figure 10. Each connector comprises a centre plate 931 bonded to the external surface of the inflatable form 10, with a low profile cylindrical cup 932 extending from a central region thereof. These act as locators for an elongate rod 933 provided with two nuts 934 for engaging through holes 916 formed in the masking plate 910.

[00135] The internal diameter of the cylindrical cup 932 is fractionally larger than the external diameter the rod 933, such that one end of the rod can be located in the cup.

The rod is releasably mounted in the cup by mears of a pin 935 inserted through holes 936 formed in the side walls of the cup, and a corresponding through hole 937 formed in the end of the rod.

[00136] As indicated in figure 9b, some of the rods 933 may be bent along their length, to extend substantially horizontally from the surface of the inflatable form 10.

[00137] The rods 933 are inserted through openings 916 formed in the corners and top of the masking plate 910, and the nuts 934 are tightened to secure the masking plate in a vertical orientation, with the centre of its bottom edge in contact with the surface of the inflatable form 10.

[00138] Cables 938 are attached to each of the pins 935, and access holes 918 are provided in the masking plate 910, to allow a construction worker to access these cables, and thereby withdraw the pins 935 to disengage the rods 933 from the cups 932. This allows the masking plate 910 to be disengaged from the inflatable form 10 once the concrete shell has been completed, and stored for reuse.

-31 - [00139] The surround 920 is attached to the plate element by means of elasticated cords 924 provided at regular intervals around the surround. The cords are inserted through holes 926 formed in the masking plate 910, and hooked onto projections 928 on the external surface of the masking plate.

[00140] The door moulding comprises a similar arrangement to the window moulding described above, except that the surround only surrounds the top and side surfaces of the door opening.

[00141] A circular moulding 13 is located around the centre pole to mask out a circular region at the top of the dome.

[00142] As described above, the centre pole 15 extends through an opening in the top of the inflatable form 10. In the present embodiment, the centre pole extends by approximately 3m (120 inches) above the top of the form, and acts as a support for a tent or marquee structure, which provides a shelter for the inflatable form 10 during the construction process.

[00143] In this respect, the tent comprises an octagonal canopy 16 supported in the centre at its highest point by the central pole 15, and at its eight corners by shorter vertical tent poles 17 located at equal intervals and at a constant radial distance from the centre pole. The vertical tent poles may each be supported by one or more guy ropes (not shown) anchored to the ground in a known manner.

[00144] The tent is configured to ensure at least a 2m (80 inches) clearance between the canopy 16 and the rotatable -32 -support structure 1100 (described in more detail below) at any point. This is to allow sufficient room beneath the canopy for a construction worker to work on the support structure.

[00145] The centre pole 15 may also be used to support rotatable support frame 1100, shown in figure 11, for supporting a construction worker, to facilitate the application of concrete to the surface of the inflatable form 10.

[00146] The rotatable support frame comprises a ladder 1110, a platform 1120 and a connector 1130 for engaging the centre pole 15.

[00147] The connector 1130 comprises a sleeve portion 1132 which fits over the centre pole, and rests on a pin 1140, inserted through the centre pole 15. The pin retains the connector at a fixed height above the inflatable form 10, but leaves it free to rotate about the centre pole 15. A frame section 1134 mounted to the sleeve section extends therefrom radially outwardly from the sleeve section, and comprises a pair of projections 1136 for engagement with corresponding recesses formed at one end of the platform 1120.

[00148] Thus, when engaged with the connector 1130, the platform 1120 is suspended at one end from the centre pole 15, and extends in a substantially horizontal plane over the inflatable form 10, to overhang the outer edge of the form by a predetermined distance.

[00149] The other end of the platform is supported by the ladder 1110. The ladder 1110 comprises a series of steps 1112 supported by a collapsible frame 1114, which has a -33 -rectangular base, and a wheel 1116 provided at each corner.

[00150] Due to the rotatable engagement of the connector 1130 with the centre pole 15, and rotatable support frame 1100 can be moved along a circular path along the ground around the inflatable form 10.

[00151] Hand rails 1118/1128 are provided either side of the ladder and the platform for reasons of safety. In use, a construction worker can move the ladder structure to a desired location, and can stand at a desired position on the ladder or the platform, for convenient access to any position on the surface of the inflatable form 10.

[00152] To construct a dome shell structure in accordance with an embodiment of the present invention, a suitable site is selected, and the ground is cleared and levelled. A circular area with a diameter equal to the desired external diameter of the finished dome is marked out on the ground.

Anchor rods are inserted into the ground at equal intervals around the circumference of this area. A damp proof plastic sheet is layed out over the circle, and cut 15cm (6 inches) larger than the diameter of the circle. A centre plate with a cup portion at its centre is placed on the ground within the circle, with the cup portion centred on the centre of the circle, and fixed in place with a further anchor rod.

[00153] The inflatable form 10 is laid out over the damp proof plastic sheet, with the locators of the door and window connectors 930 located approximately at their intended positions with respect to the circumference of the circle.

[00154] The interior of the inflatable form 10 is accessed through the access opening 35 in the main door region 30. The cup portion of the centre plate is inserted -34 -through the opening in the centre of the base section 12, and the edge defining the opening is sealed around the cup with ties.

[00155] The first end of the first pole section of the centre pole 15 is located in the cup portion, and screwed in place to extend vertically upwards. The lower sleeve member 510 is slotted onto the first pole section, and secured in position. The upper sleeve member 520 is slotted onto the first pole section above the lower section, and left free to slide along the axis of the pole.

[00156] The opening in the centre of the top section of the inflatable form 10 is then slotted over the first pole section, which thus projects externally of the inflatable form, 10.

[00157] From a position outside the form, the connector 1130 of the rotatable support frame 1100 is slotted onto the first pole section, followed by an opening formed in the centre of the tent canopy 16. The first end of the second pole section is screwed into the second end of the first section, and the first end of the third pole section is screwed into the second end of the second section, to form the centre pole 15.

[00158] The assembled centre pole is drawn into a vertical orientation, and secured in this position by pegging guy ropes attached to the second end of the third pole section (ie, the top of the centre pole 15) into the ground.

[00159] The tent canopy 16, the connector 1130, and the top of the inflatable form are drawn up the centre pole 15 using a pulley system, and secured in position.

-35 - [00160] The eight tent poles 17 are inserted in the ground at equal intervals around the form, and attached to the eight corners of the canopy 16. Guy ropes are pegged into the ground around the tent structure to support the tent poles in a vertical orientation.

[00161] A pump (not shown) is connected to the inflation opening 31 in the main door region 30 of the inflatable form via an inflation hose (not shown) . The manometer 34 is mounted to the outside of the form in the same region. The pressure release valve 33 is mounted to a further opening in the main door region 30.

[00162] The pressure inside the form is raised to a first inflation pressure of approximately 10mm (1/4 inch) of water column pressure. At this pressure, the shape of the dome is defined, but the pressure is not high enough to cause the base of the form to bulge out.

[00163] Inside the inflatable form 10, the upper sleeve member 520 is slid up the central pole 15, to a position higher than its final intended position, and secured in place using pn 534.

[00164] The eight arc shaped sections of the ring beam 410, the first elongate elements of the spoke members 420 (which are pre-attached to the support members 430 and side support members 470) and the second elongate elements of the spoke members are introduced into the inflatable form 10 through the access opening 35, and the access opening is zipped close to seal the balloon.

[00165] The ring beam 410 is assembled inside the inflatable form 10, by inserting one end of each arc shaped section into the other end of another arc shaped section, to -36 -form a ring around the centre pole 15. The arc shaped sections are initially configured to overlap to their maximum extent, to create a ring with a smaller diameter than the circular base 12 of the form.

[00166] Once assembled, the ring beam 410 is centred on the centre pole 15, and is gradually expanded at each connection point using an expansion tool (not shown) , until the diameter of the ring beam matches that of the base of the form 12.

[00167] Once the ring beam 410 is in position, first elongate elements of the eight spoke members 420 are hooked onto the respective openings 412 on the ring beam 410, the second elongate elements are connected thereto, and then attached to the respective attachment points 522 on the upper sleeve member 520.

[00168] The side support members 470 are unfolded from their collapsed state adjacent the spoke members 420, and attached to respective attachment points 416 on the ring beam 410 to provide diagonal supports at the base of the spoke members.

[00169] The support members 430 are unfolded from their collapsed state adjacent the spoke members 420 and attached to respective attachment points 512 on the lower sleeve member 510.

[00170] Once the spoke and support members 420, 430, 470 are in place, the pin 534 securing the upper sleeve member 520 is removed, and the upper sleeve member is drawn down the centre pole 15 by means of a ratchet strap (not shown) This forces the ring beam 410 downwards, due to the connection between these elements formed by the spoke members -37 - 420. The upper sleeve member is ratcheted down the centre pole until the ring beam lies at ground level, ie, until it is level with the base section 12 in its central region.

The upper sleeve member is then secured in position by replacing the pin.

[001711 The suspension cables 440, which are pre-attached to attachment points 452, 462 on the base surface 12 of the inflatable form via the vert�cal cables 450 and the diagonal cables 460, are attached to the ring beam 410 and the upper sleeve member 520. First, the eight main cables 440 are clipped into the eyelets 414 formed on the ring beam 410, and then to the eyelets 524 formed on the upper sleeve member 520. As three eyelets are available for each cable, the cable is clipped into the highest eyelet that can be reached. The cables are then tightened in turn using a turn buckle tensioner (not shown) located between the cable and the clip, to achieve the desired tension.

[001721 Once the main cables 440 are in place, the vertical cables 450 extend substantially vertically between the base section 12 and the main cables 440, whilst the diagonal cables extend diagonally therebetween.

[00173] This completes the assembly of the internal structure 400. Once the internal structure 400 is in place, the interior of the inflatable form 10 is vacated by the construction personnel, and the access opening 35 is sealed by zipping up the opening of the access tube 37, rolling up the access tube, and lacing up the slit 36 over the rolled up tube.

[00174] The pressure inside the inflatable form 10 is then increased to a second inflation pressure 50mm (2 inches) of water column pressure. At this pressure, the opening in -38 -the top of the form is sealed to the centre pole 15 using ties.

[00175] The rotatable support structure 1100 is connected to the connector 1130.

[00176] A circular moulding 13 is located around the centre pole 15 to mask out a circular region at the top of the inflatable form 10.

[00177] The window moulLdings 19 are mounted to the exterior surface of the inflatable form 10.

[00178] To mount the window mouldings to the inflatable form, an attachment rod 933 is located in the cup section 932 of each locator on the surface of the form. Appropriate rods 933 are selected, such that the screw threaded end of the rod projects from the form substantially horizontally.

[00179] The openings 916 in the masking plates 910 are slotted onto the respective attachment rods 933, and secured in position by means of the nuts 934. The masking plates are located with the centres of their bottom surfaces 914 in contact with the surface of the form, and to extend upwards in the vertical plane which includes the tangent to the surface of the inflatable form at the bottom edge of the masking plate.

[00180] The surrounds 920 are then located around the masking plates 910 to bridge the gap between the edge of the window plates and the surface of the inflatable form 10.

The surrounds are attached to the window plates by means of elastic cords 924, which are inserted through openings 926 in the masking plates, and hooked around projections 928 mounted on the masking plates.

-39 - [00181] The door moulding is located on the inflatable form 10 in a similar manner.

[00182] The pressure in the inflatable form 10 is increased to a third pressure, or final construction pressure, or approximately, 100-150mm (4-6 inches) of water column pressure. In practice, the final construction pressure is determined in accordance with the desired thickness of the concrete shell.

[00183] The position of the mouldings 19 is checked and adjusted if necessary. Once correctly located, the window and door surrounds are taped to the form and the plate members. The tape prevents the ingress of settable material between the inflatable form and the mouldings.

[00184] In this state, the assembly is ready for the concrete layer to be applied. A glass reinforced concrete mix is prepared. A layer of the mix is sprayed or otherwise applied to the external surface of the form and window surround mouldings and allowed to set. The final construction pressure within the form is maintained while the shell sets.

[00185] Once the concrete shell has fully set, the construction assembly is removed.

[00186] Initially, the attachment rods 933 connecting the inflatable form 10 to the window and door mouldings are released by locating the cords attached to the pins through the access openings 918 in the masking plates and using these to withdraw the pins 935. This disengages the mouldings from the form.

-40 - [00187] The pressure release valve is deactivated to allow a�r to escape therethrough, to partially deflate the inflatable form 10. The access opening 35 is then opened, to allow further deflation of the form. The internal structure 400 is disassembled inside the balloon starting with the main suspension cables 440, which are left coupled to base surface 12 of the form by means of the vertical and diagonal cables 450, 460, followed by the spoke and support members 420, 440, 450 and the ring beam 410.

[00188] The disassembled structural elements are passed out through the access hole 35, through the doorway of the concrete dome, and stored for reuse. The inflatable form 10 can then be fully deflated using a suction pump. The form is then rolled up towards the centre pole 15.

[00189] The circular roof moulding is removed from inside the dome, leaving a circular opening in the shell which acts as an opening for a chimney in the completed structure, if so desired.

[00190] The window arid door surrounds 920 are disconnected from the respective masking plates 910, and peeled away from the internal surface of the concrete shell.

The masking plates are then pressed inwards from outside the dome, to fall inwards leaving window and door shaped openings. The mouldings are then removed from the dome through the door opening, and stored for reuse.

[00191] Once the structure is complete, centre pole 15, canopy 16 and tent poles 17 are removed and stored for reuse. The removal of the centre pole releases the (now deflated) inflatable form 10, so that this can be removed through the door and stored for reuse.

-41 - [00192] At this stage, plumbing and electrical conduit are laid. The internal walls are then sprayed with an insulation material (if required), followed by an internal GRC (glass fibre reinforced concrete) cover coat (if required), to provide a smooth finish.

[00193] Once the form is removed, suitable flooring is installed.

[00194] Internal walls, electrical fittings and other installations can then be installed as desired.

[00195] A further embodiment of the invention is illustrated in figure 12. In this embodiment, the metal ring beam of the first embodiment is replaced by an inflatable tube section 1210 which is integrated into the sheet material of the inflatable form 10, and extends around the periphery of the form in a region where the base section 12 meets the domed top section 11. The inflatable tube section comprises an inflation opening 1202 which can be connected via an inflation hose to a pump, such that the tube can be inflated to form a ring support for constraining the shape of the inflatable form 1210 as it inflates.

[00196] When inflated, typically to a higher pressure than the final construction pressure of the inflatable form, the inflatable tube section 1210 forms a ring support which constrains the shape of the form in the same way at the ring beam 410 of the first embodiment.

[00197] If necessary, the inflatable ring support may be used in combination with the spoke and support members 420, 430, 470 and/or the suspension cables 440, 450, 460.

[00198] Alternatively, these elements may be replaced by -42 -additional inflatable tube sections, as illustrated in figures 13 and 14.

[00199] Figure 13 shows a cross-sectional view of a further embodiment of the invention, in which a plurality of elongate and substantially parallel tube sections 1320 are integrated into the base section 12 of an inflatable form 10, and extend from one side of an inflatable ring support 1210 to the other.

[00200] Figure 14 shows a similar view of a further embodiment, in which a grid formed of elongate tube sections 1420 is integrated in and extends over the base section 12 of the inflatable form 10.

[00201] In both cases, the inflatable tube sections 1210, 1320, 1420 are interconnected, such that they can all be inflated through a single inflation opening 1202.

[00202] It is, nevertheless, envisaged that some or all of the inflatable tube sections may not be interconnected, in which case separate inflation openings may be required.

[00203] When inflated, typically to a higher inflation pressure than the final construction pressure of the inflatable form 10, the inflatable tube sections 1320, 1420 constrain the base section 12 of the form such that it remains substantially flat as the form itself is inflated.

[00204] Figure 15 shows another alternative embodiment of the invention, in which the inflatable form 10, which comprises a domed top section 11 and a circular base section 12 is mounted to a rigid foundation slab 1530 pre-formed in the ground.

-43 - [00205] A plurality of anchors 1510, which each comprise a metal loop, are located around the periphery of the foundation layer immediately after it is poured, to be securely retained thereby once it has set.

[00206] The inflatable form 10 is then located on the foundation slab 1530, and coupled to the anchors 1510 using metal ties 1520.

[00207] In this state, the inflatable form 1510 can be inflated as described above in relation to the first embodiment.

[00208] A skirt 1540 is joined to the top surface 11 of the inflatable form 10 by a seam 1542. The skirt is omitted from figure 15 for the pirposes of illustration. In practice, the skirt will extend downwards from the seam 1542, as shown in figure 16, to cover the anchors 1520 and the ties 1522. The skirt thus shields the anchors and ties from the layer of concrete when this is applied to the surface of the form. Accordingly, the connectors do not become embedded in the concrete layer, which allows the form to be removed from the dome shell structure once formed, so that it can be reused.

[00209] Although not shown in figures 12 to 16, the assemblies illustrated in these figures may additionally comprise any of the elements described in relation to the first embodiment. Moreover, processing of these assemblies shown in figures 12 to 16, to create a dome shell structure is the same as that described in relation to the first embodiment. In particular, door and window mouldings may be applied to the surface of the forms, as described above, and, if required, a centre pole may be inserted, to support a rotatable support structure and/or a tent.

-44 - [00210] It is envisaged that the assemblies and methods described above will be suitable for the construction of dome shell structures with a base diameter in the range of approximately 2-12m.

[00211] It will be understood that the embodiments described above and illustrated in the drawings show applications of the invention only for the purposes of illustration. In practice the invention may be applied to many different configurations, the detailed embodiments being straightforward for those skilled in the art to implement.

[00212] In particular, although the above described embodiments comprises the use of an inflatable form having a closed base, certain aspects of the present invention may use a conventional inflatable form which does not include a base section. In such cases, the inflatable form may be sealed to a solid base, such as a pre-formed concrete foundation.

[00213] The present invention has been described in terms of a circular based dome. However, the dome may take other forms. For example, it may have an oval or polygonal base.

[00214] In the above described embodiment, the completed structure comprises a single dome. However, it will be appreciated that a structure made in accordance with the present invention may comprise a plurality of dome shaped modules, either overlapping or connected by passageways.

Such structures can be readily constructed, one section at a time, or by erecting a plurality of inflatable forms.

Claims

-45 -CLAIMS1. An assembly for use in the construction of a dome shell structure, the assembly comprising:-an inflatable balloon formed of a flexible sheet material, the balloon comprising a first section of said sheet material for defining a domed surface of a dome, and a second section of said sheet material for defining a base surface of a dome; wherein the assembly further comprises a ring support for supporting the balloon in the region where the first section meets the second section as the balloon inflates.
2. An assembly according to claim 1 wherein the ring beam is locatable within the balloon, to support the balloon from inside.
3. An assembly according to claim 1 or 2 wherein the ring support comprises a ring beam.
4. An assembly according to any of claims 1 to 3 wherein the ring support is formed of a plurality of interlocking components.
5. An assembly according to any of claims 1 to 4 wherein the ring support comprises an inflatable tube.
6. An assembly according to any of claims 1 to 5 wherein the ring support comprises a plurality anchors for location in the ground along the outline of a ring, for attachment to respective connectors on the inflatable balloon, to support the balloon in the region where the first section meets the second section.
7. An assembly according to claim 6 further comprising a shield member for shielding the connectors from settable -46 -material when applied to the surface of the balloon.
8. An assembly according to any preceding claim further comprising a central support for attachment to the second section of the balloon, such that the central support extends along a substantially vertically axis of the balloon.
9. An assembly according to claim 8 further comprising coupling means for coupling the central support to the ring support, to fix the vertical position of the ring support in relation to the central support.
10. An assembly according to claim 9 wherein the coupling means comprises a slidable connector, slidably engagable with the central support, for adjusting the vertical position of the ring support.
11. An assembly according to claim 9 or 10 wherein the coupling means comprises one or more elongate members which, when assembled, extend radially between the ring support and the central support.
12. An assembly according to any of claims 8 to 11 further comprising suspension means for suspending the second section of the balloon from the central support.
13. An assembly according to claim 12 wherein said suspension means comprises:-one or more supports for attachment to the central support such that they are located vertically above the second section of the balloon; and a plurality of suspension members each configured for attachment to a respective attachment point on the second section of the balloon, and to a respective attachment point on one of said one or more supports, to extend substantially -47 -vertically therebetween.
14. An assembly according to claim 13 wherein the supports comprise a plurality of elongate members, each configured for attachment to the ring support and to the central support.
15. An assembly according to any preceding claim further comprising a plurality of elongate beams, each configured for attachment to two points on the perimeter of the ring support to extend in a substantially common vertical plane.
16. An assembly according to any preceding claim further comprising a plurality of inflatable tube sections which, when inflated, extend across the second section of the balloon.
17. A method of constructing a dome shell structure, the method comprising: -providing an inflatable balloon formed of a flexible sheet material, the balloon comprising a first section of said sheet material for defining a domed surface of a dome, and a second section of said sheet material for defining a base surface of a dome; providing a ring support to support the balloon in the region where the first section meets the second section; and inflating the balloon to a predetermined pressure.
18. A method according to claim 17 comprising locating the ring support within the balloon.
19. A method according to claim 17 or 18 comprising assembling the ring support from a plurality of interlocking components.

-48 -
20. A method according to claims 17 or 18 comprising inflating an inflatable tube to form said ring support.
21. A method according to any of claims 17 to 20 comprising locating a plurality of anchors in the ground along the outline of a ring, and attaching connectors on the inflatable balloon to said anchors.
22. A method according to any of claims 17 to 21 further comprising shielding the connectors from settabiLe material during the application thereof to the surface of the balloon.
23. A method according to any of claims 17 to 22 further comprising attaching a central support to the second section of the balloon, such that the central support extends along a substantially vertically axis of the balloon.
24. A method according to claim 23 further comprising coupling the central support to the ring support, to fix the vertical position of the ring support in relation to the central support.
25. A method according to claim 24 further comprising adjusting the coupling of the central support to the ring support, to adjust the vertical position of the ring support in relation to the central support.
26. A method according to any of claims 17 to 25 further comprising suspending the second section of the balloon from one or more supports attached to the central support, and located vertically above the second section of the balloon.
27. A method according to any of claims 17 to 26 comprising attaching each of a plurality of elongate beams at two points on the ring support to extend over the second -49 -section of the inflatable balloon.
28. A method according to any of claims 17 to 27 comprising inflating a plurality of inflatable tube sections to extend across the second section of the balloon.
29. An assembly for use in the construction of a dome shell structure, the assembly comprising:-an assembly for use in the construction of a dome shell structure, the assembly comprising:-an inflatable form for defining a domed surface; and one or more mouldings for defining door and/or window surrounds on said domed surface; wherein the or each moulding is releasably mountable to the Thflatable form.
30. An assembly according to claim 29 wherein the or each moulding is removable from the dome shell structure, once formed.
31. An assembly according to claim 29 or 30 wherein the or each moulding comprises a surround section which, when mounted on the inflatable form, projects from the domed surface thereof to at least partially surround a door or window opening.
32. An assembly according to any of claims 29 to 31 wherein the or each moulding comprises a masking section for masking a door or window opening.
33. An assembly according to claim 32 as dependent on claim 31 wherein the masking section and the surroUnd section are separable.
34. An assembly according to any of claims 29 to 33 -50 -wherein the or each moulding is releasably mountable to the inflatable form by one or more releasable connectors.
35. An assembly according to claim 34 wherein the or each releasable connector comprises a locator mounted at a predetermined position on the inflatable form, and an elongate member, releasably locatable in said locator to extend outwards from the domed surface defined by theinflatable form.
36. An assembly according to claim 35 wherein the or each moulding is formed with one or more openings, the or each opening being configured to engage a respective one of the one or more elongate members.
37. An assembly according to claim 36 wherein the or each elongate member comprises a securing device for securing the moulding to the elongate member at a predetermined distance from the domed surface.
38. An assembly according to claim 36 or 37 wherein the or each opening is provided on the masking section of the moulding.
39. An assembly according to any of claims 35 to 38 wherein one or more access openings are provided in the masking section, to allow the elongate members to be disengaged from the locators from outside the assembly.
40. A method of forming one or more doors and/or windows in a dome shell structure, the method comprising:-inflating an inflatable form to provide a domed surface; releasably mounting one or more mouldings to said domed surface, wherein the or each moulding and comprises a -51 -surround section which projects from the domed surface of the inflatable form to at least partially surround door or window opening; applying one or more layers of setting material to the domed surface and a surface of the surround section of the or each moulding; allowing the setting material to set to form a rigid shell; disconnecting the or each moulding from theinflatable form; andremoving the inflatable form.
41. A method according to claim 40 further comprising removing the moulding from the rigid shell once the setting material has set.
42. A method according to claim 40 or 41 wherein the step of releasably mounting the or each moulding to the inflatable form comprises locating an elongate member in a locator mounted at a predetermined position on the inflatable form, to extend outwards from the domed surface defined by theinflatable form.
43. A method according to claim 42 further comprising slotting one or more openings formed at corresponding locations on the or each moulding onto the or each elongate member.
44. A method according to claim 42 further comprising securing the moulding to the or each elongate member at a predetermined distance from the domed surface.
45. A method according to any of claims 40 to 44 wherein the step of disconnecting the or each moulding from the inflatable form comprises disengaging the elongate members -52 -from the locators.
46. An assembly for use in the construction of a dome shell structure, the assembly comprising:-an inflatable form for defining a domed surface; and a central support which, when assembled, extends along a substantially vertical axis of the form, through an opening in the domed surface of the form.
47. An assembly according to claim 46 further comprising a canopy for location on said central support, to form a shelter over the inflatable form during construction of the dome shell structure.
48. An assembly according to claim 46 or 47 further comprising a support structure for supporting a construction worker during construction of the dome shell structure, wherein the support structure is rotatably mountable to said central support.
49. A method of constructing a dome shell structure, the method comprising: -inflating an inflatable form to provide a domed surface; and assembling a central support to extend along a substantially vertical axis of the form, through an opening in the domed surface of the form.
50. A method according to claim 49 further comprising locating a canopy for location on said central support, to form a shelter over the inflatable form during construction of the dome shell structure.
51. A method according to claim 49 or 50 further comprising rotatably mounting to said central support, a -53 -support structure for supporting a construction worker during construction of the dome shell structure.
52. An assembly for use in the construction of a dome shell structure, substantially as hereinbefore described with reference to the accompanying drawings.
53. A method of constructing a dome shell structure, substantially as hereinbefore described with reference to the accompanying drawings.
54. A method of forming one or more doors and/or windows in a dome shell structure, substantially as hereinbefore described with reference to the accompanying drawings.